diff --git a/Cargo.lock b/Cargo.lock
index fcdab3fc..f0b0fa22 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1943,6 +1943,7 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "77727bb15fa921304124b128af125e7e3b968275d1b108b379190264f4423710"
 dependencies = [
+ "getrandom 0.4.2",
  "hybrid-array",
  "rand_core 0.10.1",
 ]
@@ -6418,6 +6419,7 @@ dependencies = [
  "bytesize",
  "chacha20",
  "k256",
+ "ml-kem",
  "risc0-zkvm",
  "serde",
  "serde_json",
diff --git a/integration_tests/tests/auth_transfer/private.rs b/integration_tests/tests/auth_transfer/private.rs
index 4d268b89..09246caf 100644
--- a/integration_tests/tests/auth_transfer/private.rs
+++ b/integration_tests/tests/auth_transfer/private.rs
@@ -7,7 +7,7 @@ use integration_tests::{
 };
 use log::info;
 use nssa::{AccountId, program::Program};
-use nssa_core::{NullifierPublicKey, encryption::shared_key_derivation::Secp256k1Point};
+use nssa_core::{NullifierPublicKey, encryption::ViewingPublicKey};
 use sequencer_service_rpc::RpcClient as _;
 use tokio::test;
 use wallet::cli::{
@@ -63,7 +63,7 @@ async fn private_transfer_to_foreign_account() -> Result<()> {
     let from: AccountId = ctx.existing_private_accounts()[0];
     let to_npk = NullifierPublicKey([42; 32]);
     let to_npk_string = hex::encode(to_npk.0);
-    let to_vpk = Secp256k1Point::from_scalar(to_npk.0);
+    let to_vpk = ViewingPublicKey::from_seed(&to_npk.0, &[0u8; 32]);
 
     let command = Command::AuthTransfer(AuthTransferSubcommand::Send {
         from: Some(format_private_account_id(from)),
@@ -274,7 +274,7 @@ async fn shielded_transfer_to_foreign_account() -> Result<()> {
 
     let to_npk = NullifierPublicKey([42; 32]);
     let to_npk_string = hex::encode(to_npk.0);
-    let to_vpk = Secp256k1Point::from_scalar(to_npk.0);
+    let to_vpk = ViewingPublicKey::from_seed(&to_npk.0, &[0u8; 32]);
     let from: AccountId = ctx.existing_public_accounts()[0];
 
     let command = Command::AuthTransfer(AuthTransferSubcommand::Send {
diff --git a/integration_tests/tests/private_pda.rs b/integration_tests/tests/private_pda.rs
index 518239e7..6ceb3efe 100644
--- a/integration_tests/tests/private_pda.rs
+++ b/integration_tests/tests/private_pda.rs
@@ -229,10 +229,10 @@ async fn private_pda_family_members_receive_and_spend() -> Result<()> {
 
     // Fresh recipients — hardcoded npks not in any wallet.
     let recipient_npk_0 = NullifierPublicKey([0xAA; 32]);
-    let recipient_vpk_0 = ViewingPublicKey::from_scalar(recipient_npk_0.0);
+    let recipient_vpk_0 = ViewingPublicKey::from_seed(&recipient_npk_0.0, &[0u8; 32]);
 
     let recipient_npk_1 = NullifierPublicKey([0xBB; 32]);
-    let recipient_vpk_1 = ViewingPublicKey::from_scalar(recipient_npk_1.0);
+    let recipient_vpk_1 = ViewingPublicKey::from_seed(&recipient_npk_1.0, &[0u8; 32]);
 
     let amount_spend_0: u128 = 13;
     let amount_spend_1: u128 = 37;
diff --git a/integration_tests/tests/shared_accounts.rs b/integration_tests/tests/shared_accounts.rs
index c5d937e0..95b86d1d 100644
--- a/integration_tests/tests/shared_accounts.rs
+++ b/integration_tests/tests/shared_accounts.rs
@@ -101,9 +101,12 @@ async fn group_invite_join_key_agreement() -> Result<()> {
         .storage()
         .user_data
         .sealing_secret_key
+        .clone()
         .context("Sealing key not found")?;
     let sealing_pk =
-        key_protocol::key_management::group_key_holder::SealingPublicKey::from_scalar(sealing_sk);
+        key_protocol::key_management::group_key_holder::SealingPublicKey::from_bytes(
+            nssa_core::encryption::ViewingPublicKey::from_seed(&sealing_sk.d, &sealing_sk.r).0,
+        );
 
     let holder = ctx
         .wallet()
diff --git a/integration_tests/tests/tps.rs b/integration_tests/tests/tps.rs
index 1f132932..3a027277 100644
--- a/integration_tests/tests/tps.rs
+++ b/integration_tests/tests/tps.rs
@@ -209,8 +209,7 @@ pub async fn tps_test() -> Result<()> {
 fn build_privacy_transaction() -> PrivacyPreservingTransaction {
     let program = Program::authenticated_transfer_program();
     let sender_nsk = [1; 32];
-    let sender_vsk = [99; 32];
-    let sender_vpk = ViewingPublicKey::from_scalar(sender_vsk);
+    let sender_vpk = ViewingPublicKey::from_seed(&[99u8; 32], &[100u8; 32]);
     let sender_npk = NullifierPublicKey::from(&sender_nsk);
     let sender_pre = AccountWithMetadata::new(
         Account {
@@ -223,8 +222,7 @@ fn build_privacy_transaction() -> PrivacyPreservingTransaction {
         AccountId::for_regular_private_account(&sender_npk, 0),
     );
     let recipient_nsk = [2; 32];
-    let recipient_vsk = [99; 32];
-    let recipient_vpk = ViewingPublicKey::from_scalar(recipient_vsk);
+    let recipient_vpk = ViewingPublicKey::from_seed(&[99u8; 32], &[100u8; 32]);
     let recipient_npk = NullifierPublicKey::from(&recipient_nsk);
     let recipient_pre = AccountWithMetadata::new(
         Account::default(),
@@ -232,13 +230,13 @@ fn build_privacy_transaction() -> PrivacyPreservingTransaction {
         AccountId::for_regular_private_account(&recipient_npk, 0),
     );
 
-    let eph_holder_from = EphemeralKeyHolder::new(&sender_npk);
-    let sender_ss = eph_holder_from.calculate_shared_secret_sender(&sender_vpk);
-    let sender_epk = eph_holder_from.generate_ephemeral_public_key();
+    let eph_holder_from = EphemeralKeyHolder::new(&sender_vpk);
+    let sender_ss = eph_holder_from.calculate_shared_secret_sender();
+    let sender_epk = eph_holder_from.ephemeral_public_key().clone();
 
-    let eph_holder_to = EphemeralKeyHolder::new(&recipient_npk);
-    let recipient_ss = eph_holder_to.calculate_shared_secret_sender(&recipient_vpk);
-    let recipient_epk = eph_holder_from.generate_ephemeral_public_key();
+    let eph_holder_to = EphemeralKeyHolder::new(&recipient_vpk);
+    let recipient_ss = eph_holder_to.calculate_shared_secret_sender();
+    let recipient_epk = eph_holder_to.ephemeral_public_key().clone();
 
     let balance_to_move: u128 = 1;
     let proof: MembershipProof = (
diff --git a/key_protocol/src/key_management/ephemeral_key_holder.rs b/key_protocol/src/key_management/ephemeral_key_holder.rs
index 36600493..dc223390 100644
--- a/key_protocol/src/key_management/ephemeral_key_holder.rs
+++ b/key_protocol/src/key_management/ephemeral_key_holder.rs
@@ -1,54 +1,61 @@
 use nssa_core::{
-    NullifierPublicKey, SharedSecretKey,
-    encryption::{EphemeralPublicKey, EphemeralSecretKey, ViewingPublicKey,
-    shared_key_derivation::Secp256k1Point},
+    SharedSecretKey,
+    encryption::{EphemeralPublicKey, ViewingPublicKey},
 };
-use rand::{RngCore as _, rngs::OsRng};
-use sha2::Digest as _;
 
-#[derive(Debug)]
-/// Ephemeral secret key holder. Non-clonable as intended for one-time use. Produces ephemeral
-/// public keys. Can produce shared secret for sender.
+/// Ephemeral key holder for the sender side of a KEM-based shared-secret exchange.
+///
+/// Non-clonable as intended for one-time use: construction encapsulates once and
+/// stores both the shared secret and the ciphertext (EphemeralPublicKey) that must
+/// be sent to the receiver.
 pub struct EphemeralKeyHolder {
-    ephemeral_secret_key: EphemeralSecretKey,
+    shared_secret: SharedSecretKey,
+    ephemeral_public_key: EphemeralPublicKey,
+}
+
+// Marvin-pq: SharedSecretKey does not implement Debug (intentional — leaking key material via
+// debug output would be a security risk). We implement Debug manually here, redacting the
+// shared secret while still allowing the ephemeral public key (KEM ciphertext) to be inspected.
+impl std::fmt::Debug for EphemeralKeyHolder {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("EphemeralKeyHolder")
+            .field("shared_secret", &"<redacted>")
+            .field("ephemeral_public_key", &self.ephemeral_public_key)
+            .finish()
+    }
 }
 
 impl EphemeralKeyHolder {
     #[must_use]
-    pub fn new(receiver_nullifier_public_key: &NullifierPublicKey) -> Self {
-        let mut nonce_bytes = [0; 16];
-        OsRng.fill_bytes(&mut nonce_bytes);
-        let mut hasher = sha2::Sha256::new();
-        hasher.update(receiver_nullifier_public_key);
-        hasher.update(nonce_bytes);
-
+    pub fn new(receiver_viewing_public_key: &ViewingPublicKey) -> Self {
+        let (shared_secret, ephemeral_public_key) =
+            SharedSecretKey::encapsulate(receiver_viewing_public_key);
         Self {
-            ephemeral_secret_key: hasher.finalize().into(),
+            shared_secret,
+            ephemeral_public_key,
         }
     }
 
+    /// Returns the KEM ciphertext to be transmitted to the receiver as the EphemeralPublicKey.
     #[must_use]
-    pub fn generate_ephemeral_public_key(&self) -> EphemeralPublicKey {
-        EphemeralPublicKey::from_scalar(self.ephemeral_secret_key)
+    pub fn ephemeral_public_key(&self) -> &EphemeralPublicKey {
+        &self.ephemeral_public_key
     }
 
+    /// Returns the sender-side shared secret (established at construction time).
     #[must_use]
-    pub fn calculate_shared_secret_sender(
-        &self,
-        _receiver_viewing_public_key: &ViewingPublicKey,
-    ) -> SharedSecretKey {
-        SharedSecretKey::new(&self.ephemeral_secret_key, &Secp256k1Point::from_scalar(self.ephemeral_secret_key))
+    pub fn calculate_shared_secret_sender(&self) -> SharedSecretKey {
+        self.shared_secret
     }
 }
 
+/// Encapsulates a fresh shared secret toward `vpk` and returns `(shared_secret, ciphertext)`.
+///
+/// Used when the local side is acting as an "ephemeral receiver" — i.e. generating a
+/// one-sided encryption that only the holder of the VSK can decrypt.
 #[must_use]
 pub fn produce_one_sided_shared_secret_receiver(
-    _vpk: &ViewingPublicKey,
+    vpk: &ViewingPublicKey,
 ) -> (SharedSecretKey, EphemeralPublicKey) {
-    let mut esk = [0; 32];
-    OsRng.fill_bytes(&mut esk);
-    (
-        SharedSecretKey::new(&esk, &Secp256k1Point::from_scalar(esk)),
-        EphemeralPublicKey::from_scalar(esk),
-    )
+    SharedSecretKey::encapsulate(vpk)
 }
diff --git a/key_protocol/src/key_management/group_key_holder.rs b/key_protocol/src/key_management/group_key_holder.rs
index f345789d..7aec47bb 100644
--- a/key_protocol/src/key_management/group_key_holder.rs
+++ b/key_protocol/src/key_management/group_key_holder.rs
@@ -1,44 +1,39 @@
 use aes_gcm::{Aes256Gcm, KeyInit as _, aead::Aead as _};
 use nssa_core::{
     SharedSecretKey,
-    encryption::{Scalar, shared_key_derivation::Secp256k1Point},
+    encryption::{EphemeralPublicKey, ViewingPublicKey},
     program::{PdaSeed, ProgramId},
 };
 use rand::{RngCore as _, rngs::OsRng};
 use serde::{Deserialize, Serialize};
 use sha2::{Digest as _, digest::FixedOutput as _};
 
-use super::secret_holders::{PrivateKeyHolder, SecretSpendingKey};
+use super::secret_holders::{PrivateKeyHolder, SecretSpendingKey, ViewingSecretKey};
 
 /// Public key used to seal a `GroupKeyHolder` for distribution to a recipient.
 ///
-/// Wraps a secp256k1 point but is a distinct type from `ViewingPublicKey` to enforce
-/// key separation: viewing keys encrypt account state, sealing keys encrypt the GMS
-/// for off-chain distribution.
-pub struct SealingPublicKey(Secp256k1Point);
+/// Wraps the ML-KEM-768 encapsulation key bytes (1184 bytes). Distinct from
+/// `ViewingPublicKey` to enforce key separation: viewing keys encrypt account state,
+/// sealing keys encrypt the GMS for off-chain distribution.
+pub struct SealingPublicKey(Vec<u8>);
 
 impl SealingPublicKey {
-    /// Derive the sealing public key from a secret scalar.
-    #[must_use]
-    pub fn from_scalar(scalar: Scalar) -> Self {
-        Self(Secp256k1Point::from_scalar(scalar))
-    }
-
-    /// Construct from raw serialized bytes (e.g. received from another wallet).
+    /// Construct from raw serialized encapsulation-key bytes (e.g. received from another wallet).
     #[must_use]
     pub const fn from_bytes(bytes: Vec<u8>) -> Self {
-        Self(Secp256k1Point(bytes))
+        Self(bytes)
     }
 
     /// Returns the raw bytes for display or transmission.
     #[must_use]
     pub fn to_bytes(&self) -> &[u8] {
-        &self.0.0
+        &self.0
     }
 }
 
 /// Secret key used to unseal a `GroupKeyHolder` received from another member.
-pub type SealingSecretKey = Scalar;
+/// Holds the two 32-byte FIPS 203 seed halves `d` and `r`.
+pub type SealingSecretKey = ViewingSecretKey;
 
 /// Manages shared viewing keys for a group of controllers owning private PDAs.
 ///
@@ -151,20 +146,25 @@ impl GroupKeyHolder {
         SecretSpendingKey(hasher.finalize_fixed().into()).produce_private_key_holder(None)
     }
 
+    // Marvin-pq: seal_for/unseal switched from ECDH (Secp256k1) to ML-KEM-768.
+    // Wire format changed from:
+    //   ephemeral_pubkey (33) || nonce (12) || ciphertext+tag (48)  = 93 bytes
+    // to:
+    //   kem_ciphertext (1088) || nonce (12) || ciphertext+tag (48)  = 1148 bytes
+    // SealingSecretKey is now the FIPS 203 seed pair (d, r) = ViewingSecretKey.
+
     /// Encrypts this holder's GMS under the recipient's [`SealingPublicKey`].
     ///
-    /// Uses an ephemeral ECDH key exchange to derive a shared secret, then AES-256-GCM
-    /// to encrypt the payload. The returned bytes are
-    /// `ephemeral_pubkey (33) || nonce (12) || ciphertext+tag (48)` = 93 bytes.
+    /// Uses ML-KEM-768 encapsulation to derive a shared secret, then AES-256-GCM to encrypt
+    /// the payload. The returned bytes are
+    /// `kem_ciphertext (1088) || nonce (12) || ciphertext+tag (48)` = 1148 bytes.
     ///
-    /// Each call generates a fresh ephemeral key, so two seals of the same holder produce
+    /// Each call generates a fresh KEM encapsulation, so two seals of the same holder produce
     /// different ciphertexts.
     #[must_use]
     pub fn seal_for(&self, recipient_key: &SealingPublicKey) -> Vec<u8> {
-        let mut ephemeral_scalar: Scalar = [0_u8; 32];
-        OsRng.fill_bytes(&mut ephemeral_scalar);
-        let ephemeral_pubkey = Secp256k1Point::from_scalar(ephemeral_scalar);
-        let shared = SharedSecretKey::new(&ephemeral_scalar, &recipient_key.0);
+        let vpk = ViewingPublicKey(recipient_key.0.clone());
+        let (shared, kem_ct) = SharedSecretKey::encapsulate(&vpk);
         let aes_key = Self::seal_kdf(&shared);
         let cipher = Aes256Gcm::new(&aes_key.into());
 
@@ -176,12 +176,12 @@ impl GroupKeyHolder {
             .encrypt(&nonce, self.gms.as_ref())
             .expect("AES-GCM encryption should not fail with valid key/nonce");
 
-        let capacity = 33_usize
+        let capacity = 1088_usize
             .checked_add(12)
             .and_then(|n| n.checked_add(ciphertext.len()))
             .expect("seal capacity overflow");
         let mut out = Vec::with_capacity(capacity);
-        out.extend_from_slice(&ephemeral_pubkey.0);
+        out.extend_from_slice(&kem_ct.0);
         out.extend_from_slice(&nonce_bytes);
         out.extend_from_slice(&ciphertext);
         out
@@ -189,20 +189,23 @@ impl GroupKeyHolder {
 
     /// Decrypts a sealed `GroupKeyHolder` using the recipient's [`SealingSecretKey`].
     ///
-    /// Returns `Err` if the ciphertext is too short, the ECDH point is invalid, or the
-    /// AES-GCM authentication tag doesn't verify (wrong key or tampered data).
+    /// Returns `Err` if the ciphertext is too short or the AES-GCM authentication tag
+    /// doesn't verify (wrong key or tampered data).
     pub fn unseal(sealed: &[u8], own_key: &SealingSecretKey) -> Result<Self, SealError> {
-        const HEADER_LEN: usize = 33 + 12;
+        // Marvin-pq: kem_ciphertext (1088) + nonce (12) = header, then AES-GCM tag (16) minimum.
+        const KEM_CT_LEN: usize = 1088;
+        const HEADER_LEN: usize = KEM_CT_LEN + 12;
         const MIN_LEN: usize = HEADER_LEN + 16;
+
         if sealed.len() < MIN_LEN {
             return Err(SealError::TooShort);
         }
-        // MIN_LEN (61) > HEADER_LEN (45), so all slicing below is in bounds.
-        let ephemeral_pubkey = Secp256k1Point(sealed[..33].to_vec());
-        let nonce = aes_gcm::Nonce::from_slice(&sealed[33..HEADER_LEN]);
+
+        let kem_ct = EphemeralPublicKey(sealed[..KEM_CT_LEN].to_vec());
+        let nonce = aes_gcm::Nonce::from_slice(&sealed[KEM_CT_LEN..HEADER_LEN]);
         let ciphertext = &sealed[HEADER_LEN..];
 
-        let shared = SharedSecretKey::new(own_key, &ephemeral_pubkey);
+        let shared = SharedSecretKey::decapsulate(&kem_ct, &own_key.d, &own_key.r);
         let aes_key = Self::seal_kdf(&shared);
         let cipher = Aes256Gcm::new(&aes_key.into());
 
@@ -219,7 +222,7 @@ impl GroupKeyHolder {
         Ok(Self::from_gms(gms))
     }
 
-    /// Derives an AES-256 key from the ECDH shared secret via SHA-256 with a domain prefix.
+    /// Derives an AES-256 key from the ML-KEM shared secret via SHA-256 with a domain prefix.
     fn seal_kdf(shared: &SharedSecretKey) -> [u8; 32] {
         const PREFIX: &[u8; 32] = b"/LEE/v0.3/GroupKeySeal/AES\x00\x00\x00\x00\x00\x00";
         let mut hasher = sha2::Sha256::new();
@@ -325,8 +328,7 @@ mod tests {
 
     /// Pins the end-to-end derivation for a fixed (GMS, `ProgramId`, `PdaSeed`). Any change
     /// to `secret_spending_key_for_pda`, the `PrivateKeyHolder` nsk/npk chain, or the
-    /// `AccountId::for_private_pda` formula breaks this test. Mirrors the pinned-value
-    /// pattern from `for_private_pda_matches_pinned_value` in `nssa_core`.
+    /// `AccountId::for_private_pda` formula breaks this test.
     #[test]
     fn pinned_end_to_end_derivation_for_private_pda() {
         use nssa_core::{account::AccountId, program::ProgramId};
@@ -345,8 +347,6 @@ mod tests {
             136, 176, 234, 71, 208, 8, 143, 142, 126, 155, 132, 18, 71, 27, 88, 56, 100, 90, 79,
             215, 76, 92, 60, 166, 104, 35, 51, 91, 16, 114, 188, 112,
         ]);
-        // AccountId is derived from (program_id, seed, npk), so it changes when npk changes.
-        // We verify npk is pinned, and AccountId is deterministically derived from it.
         let expected_account_id =
             AccountId::for_private_pda(&program_id, &seed, &expected_npk, u128::MAX);
 
@@ -354,10 +354,7 @@ mod tests {
         assert_eq!(account_id, expected_account_id);
     }
 
-    /// Wallets persist `GroupKeyHolder` to disk and reload it on startup. This test pins
-    /// the serde round-trip: serialize, deserialize, and assert the derived keys for a
-    /// sample seed match on both sides. A silent encoding drift would corrupt every
-    /// group-owned account.
+    /// Wallets persist `GroupKeyHolder` to disk and reload it on startup.
     #[test]
     fn gms_serde_round_trip_preserves_derivation() {
         let original = GroupKeyHolder::from_gms([7_u8; 32]);
@@ -377,10 +374,7 @@ mod tests {
     }
 
     /// A `GroupKeyHolder` constructed from the same 32 bytes as a personal
-    /// `SecretSpendingKey` must not derive the same `NullifierPublicKey` as the personal
-    /// path, so a private PDA cannot be spent by a personal nullifier even under
-    /// adversarial key-material reuse. The safety rests on the group path's distinct
-    /// domain-separation prefix plus the seed mix-in (see `secret_spending_key_for_pda`).
+    /// `SecretSpendingKey` must not derive the same `NullifierPublicKey`.
     #[test]
     fn group_derivation_does_not_collide_with_personal_path_at_shared_bytes() {
         let shared_bytes = [13_u8; 32];
@@ -405,10 +399,10 @@ mod tests {
         let recipient_ssk = SecretSpendingKey([7_u8; 32]);
         let recipient_keys = recipient_ssk.produce_private_key_holder(None);
         let recipient_vpk = recipient_keys.generate_viewing_public_key();
-        let _recipient_vsk = recipient_keys.viewing_secret_key;
+        let recipient_vsk = recipient_keys.viewing_secret_key.clone();
 
         let sealed = holder.seal_for(&SealingPublicKey::from_bytes(recipient_vpk.0));
-        let restored = GroupKeyHolder::unseal(&sealed, &Scalar::default()).expect("unseal");
+        let restored = GroupKeyHolder::unseal(&sealed, &recipient_vsk).expect("unseal");
 
         assert_eq!(restored.dangerous_raw_gms(), holder.dangerous_raw_gms());
 
@@ -433,13 +427,13 @@ mod tests {
             .produce_private_key_holder(None)
             .generate_viewing_public_key();
 
-        let wrong_ssk = SecretSpendingKey([99_u8; 32]);
-        let _wrong_vsk = wrong_ssk
+        let wrong_vsk = SecretSpendingKey([99_u8; 32])
             .produce_private_key_holder(None)
-            .viewing_secret_key;
+            .viewing_secret_key
+            .clone();
 
         let sealed = holder.seal_for(&SealingPublicKey::from_bytes(recipient_vpk.0));
-        let result = GroupKeyHolder::unseal(&sealed, &Scalar::default());
+        let result = GroupKeyHolder::unseal(&sealed, &wrong_vsk);
         assert!(matches!(result, Err(super::SealError::DecryptionFailed)));
     }
 
@@ -451,18 +445,18 @@ mod tests {
         let recipient_ssk = SecretSpendingKey([7_u8; 32]);
         let recipient_keys = recipient_ssk.produce_private_key_holder(None);
         let recipient_vpk = recipient_keys.generate_viewing_public_key();
-        let _recipient_vsk = recipient_keys.viewing_secret_key;
+        let recipient_vsk = recipient_keys.viewing_secret_key.clone();
 
         let mut sealed = holder.seal_for(&SealingPublicKey::from_bytes(recipient_vpk.0));
-        // Flip a byte in the ciphertext portion (after ephemeral_pubkey + nonce)
+        // Flip a byte in the AES-GCM ciphertext portion (after KEM ciphertext + nonce).
         let last = sealed.len() - 1;
         sealed[last] ^= 0xFF;
 
-        let result = GroupKeyHolder::unseal(&sealed, &Scalar::default());
+        let result = GroupKeyHolder::unseal(&sealed, &recipient_vsk);
         assert!(matches!(result, Err(super::SealError::DecryptionFailed)));
     }
 
-    /// Two seals of the same holder produce different ciphertexts (ephemeral randomness).
+    /// Two seals of the same holder produce different ciphertexts (KEM randomness).
     #[test]
     fn two_seals_produce_different_ciphertexts() {
         let holder = GroupKeyHolder::from_gms([42_u8; 32]);
@@ -481,14 +475,15 @@ mod tests {
     /// Sealed payload is too short.
     #[test]
     fn unseal_too_short_fails() {
-        let vsk: SealingSecretKey = [7_u8; 32];
+        let vsk = SealingSecretKey {
+            d: [7_u8; 32],
+            r: [0_u8; 32],
+        };
         let result = GroupKeyHolder::unseal(&[0_u8; 10], &vsk);
         assert!(matches!(result, Err(super::SealError::TooShort)));
     }
 
-    /// Degenerate GMS values (all-zeros, all-ones, single-bit) must still produce valid,
-    /// non-zero, pairwise-distinct npks. Rules out accidental "if gms == default { return
-    /// default }" style shortcuts in the derivation.
+    /// Degenerate GMS values must still produce valid, non-zero, pairwise-distinct npks.
     #[test]
     fn degenerate_gms_produces_distinct_non_zero_keys() {
         let seed = PdaSeed::new([1; 32]);
@@ -526,21 +521,18 @@ mod tests {
         let pda_seed = PdaSeed::new([42_u8; 32]);
         let program_id: nssa_core::program::ProgramId = [1; 8];
 
-        // Derive Alice's keys
         let alice_keys = alice_holder.derive_keys_for_pda(&TEST_PROGRAM_ID, &pda_seed);
         let alice_npk = alice_keys.generate_nullifier_public_key();
 
-        // Seal GMS for Bob using Bob's viewing key, Bob unseals
         let bob_ssk = SecretSpendingKey([77_u8; 32]);
         let bob_keys = bob_ssk.produce_private_key_holder(None);
         let bob_vpk = bob_keys.generate_viewing_public_key();
-        let _bob_vsk = bob_keys.viewing_secret_key;
+        let bob_vsk = bob_keys.viewing_secret_key.clone();
 
         let sealed = alice_holder.seal_for(&SealingPublicKey::from_bytes(bob_vpk.0));
         let bob_holder =
-            GroupKeyHolder::unseal(&sealed, &Scalar::default()).expect("Bob should unseal the GMS");
+            GroupKeyHolder::unseal(&sealed, &bob_vsk).expect("Bob should unseal the GMS");
 
-        // Key agreement: both derive identical NPK and AccountId
         let bob_npk = bob_holder
             .derive_keys_for_pda(&TEST_PROGRAM_ID, &pda_seed)
             .generate_nullifier_public_key();
diff --git a/key_protocol/src/key_management/key_tree/keys_private.rs b/key_protocol/src/key_management/key_tree/keys_private.rs
index b0ddd1b5..af285ddd 100644
--- a/key_protocol/src/key_management/key_tree/keys_private.rs
+++ b/key_protocol/src/key_management/key_tree/keys_private.rs
@@ -1,5 +1,6 @@
 use nssa_core::{NullifierPublicKey, PrivateAccountKind, encryption::ViewingPublicKey};
 use serde::{Deserialize, Serialize};
+use sha2::Digest as _;
 
 use crate::key_management::{
     KeyChain,
@@ -30,9 +31,7 @@ impl ChildKeysPrivate {
             .expect("hash_value is 64 bytes, must be safe to get last 32");
 
         let nsk = ssk.generate_nullifier_secret_key(None);
-        let vsk = SecretSpendingKey::generate_viewing_secret_key(
-            ssk.generate_viewing_secret_seed_key(None),
-        );
+        let vsk = ssk.generate_viewing_secret_seed_key(None);
 
         let npk = NullifierPublicKey::from(&nsk);
         let vpk = ViewingPublicKey::from(&vsk);
@@ -57,10 +56,18 @@ impl ChildKeysPrivate {
 
     #[must_use]
     pub fn nth_child(&self, cci: u32) -> Self {
-        let mut input = vec![];
+        let mut parent_hash = sha2::Sha256::new();
+        parent_hash.update(b"LEE/keys");
+        parent_hash.update([0u8; 16]);
+        parent_hash.update([9_u8]);
+        parent_hash.update(self.value.0.private_key_holder.nullifier_secret_key);
+        parent_hash.update(self.value.0.private_key_holder.viewing_secret_key.d);
+        parent_hash.update(self.value.0.private_key_holder.viewing_secret_key.r);
+        let parent_pt = parent_hash.finalize();
 
+        let mut input = vec![];
         input.extend_from_slice(b"LEE_seed_priv");
-        input.extend_from_slice(&self.value.0.private_key_holder.nullifier_secret_key);
+        input.extend_from_slice(&parent_pt);
         #[expect(clippy::big_endian_bytes, reason = "BIP-032 uses big endian")]
         input.extend_from_slice(&cci.to_be_bytes());
 
@@ -76,9 +83,7 @@ impl ChildKeysPrivate {
             .expect("hash_value is 64 bytes, must be safe to get last 32");
 
         let nsk = ssk.generate_nullifier_secret_key(Some(cci));
-        let vsk = SecretSpendingKey::generate_viewing_secret_key(
-            ssk.generate_viewing_secret_seed_key(Some(cci)),
-        );
+        let vsk = ssk.generate_viewing_secret_seed_key(Some(cci));
 
         let npk = NullifierPublicKey::from(&nsk);
         let vpk = ViewingPublicKey::from(&vsk);
@@ -125,7 +130,7 @@ mod tests {
     use nssa_core::{NullifierPublicKey, NullifierSecretKey};
 
     use super::*;
-    use crate::key_management;
+    use crate::key_management::{self, secret_holders::ViewingSecretKey};
 
     #[test]
     fn master_key_generation() {
@@ -158,14 +163,88 @@ mod tests {
             247, 155, 113, 122, 246, 192, 0, 70, 61, 76, 71, 70, 2,
         ]);
 
+        // Marvin-pq double check the d, r labels
+        let expected_vsk: ViewingSecretKey = ViewingSecretKey {
+            d: [
+                187, 143, 146, 12, 68, 148, 25, 203, 21, 92, 131, 2, 221, 81, 117, 62, 98, 194,
+                159, 177, 102, 254, 236, 182, 76, 242, 116, 219, 17, 166, 99, 36,
+            ],
+            r: [
+                80, 97, 83, 209, 145, 99, 168, 99, 89, 29, 153, 236, 82, 99, 134, 114, 168, 19,
+                223, 69, 34, 47, 76, 76, 15, 97, 245, 184, 25, 103, 251, 82,
+            ],
+        };
+
+        let expected_vpk: [u8; 1184] = [
+            127, 229, 162, 212, 104, 117, 4, 150, 192, 103, 122, 195, 14, 35, 12, 60, 52, 23, 220,
+            150, 100, 203, 34, 34, 127, 232, 156, 43, 218, 109, 6, 160, 67, 35, 210, 194, 25, 181,
+            118, 237, 25, 129, 51, 160, 189, 51, 99, 184, 57, 28, 121, 240, 236, 2, 170, 198, 26,
+            91, 172, 110, 52, 32, 186, 35, 179, 202, 234, 249, 15, 242, 100, 198, 168, 163, 120,
+            205, 118, 85, 195, 210, 187, 95, 150, 154, 8, 68, 165, 237, 87, 166, 101, 57, 4, 18,
+            11, 122, 235, 180, 199, 154, 165, 158, 55, 136, 30, 237, 43, 167, 215, 68, 80, 102, 0,
+            71, 90, 130, 206, 240, 215, 69, 199, 83, 7, 60, 184, 128, 230, 184, 61, 93, 201, 204,
+            165, 104, 9, 127, 220, 52, 246, 217, 131, 251, 2, 170, 133, 6, 51, 40, 224, 101, 61,
+            16, 135, 32, 182, 201, 68, 58, 171, 54, 161, 184, 243, 38, 106, 200, 251, 17, 172, 8,
+            24, 73, 230, 55, 85, 20, 147, 222, 165, 200, 116, 135, 47, 20, 227, 56, 220, 64, 120,
+            215, 245, 58, 86, 102, 149, 252, 193, 163, 160, 59, 82, 138, 249, 171, 1, 54, 199, 193,
+            171, 85, 38, 64, 56, 121, 106, 84, 57, 252, 94, 147, 16, 191, 196, 104, 47, 129, 84,
+            21, 252, 160, 81, 207, 184, 199, 3, 177, 74, 117, 115, 175, 138, 108, 36, 198, 5, 32,
+            15, 218, 3, 20, 19, 15, 251, 209, 86, 128, 139, 148, 78, 10, 34, 144, 149, 74, 102, 48,
+            59, 70, 124, 47, 193, 100, 26, 9, 104, 178, 102, 156, 199, 242, 101, 147, 161, 87, 27,
+            234, 192, 204, 41, 36, 43, 83, 219, 15, 211, 66, 91, 76, 73, 13, 113, 155, 203, 193,
+            160, 130, 84, 103, 47, 70, 100, 147, 169, 65, 119, 84, 121, 122, 161, 76, 203, 144,
+            248, 145, 22, 8, 46, 121, 44, 77, 20, 149, 66, 179, 56, 149, 231, 98, 184, 9, 64, 14,
+            67, 196, 34, 8, 123, 21, 80, 169, 168, 223, 230, 133, 0, 66, 159, 230, 69, 201, 205,
+            169, 105, 196, 21, 71, 84, 70, 58, 165, 165, 134, 186, 232, 60, 70, 51, 57, 239, 74,
+            174, 116, 234, 36, 178, 49, 42, 168, 250, 104, 141, 106, 0, 109, 52, 86, 104, 243, 62,
+            214, 137, 48, 107, 2, 152, 206, 227, 175, 147, 236, 19, 113, 27, 191, 231, 235, 167,
+            114, 104, 23, 126, 203, 94, 242, 149, 171, 115, 170, 89, 244, 58, 29, 176, 73, 203, 44,
+            8, 32, 9, 226, 32, 78, 246, 38, 235, 149, 133, 25, 243, 47, 124, 180, 200, 211, 165,
+            137, 56, 169, 117, 31, 244, 65, 91, 135, 146, 158, 20, 75, 102, 32, 65, 250, 103, 199,
+            36, 48, 31, 155, 164, 191, 222, 85, 37, 66, 243, 17, 120, 104, 0, 228, 83, 200, 116, 6,
+            199, 106, 236, 139, 246, 216, 152, 241, 211, 85, 106, 200, 44, 231, 240, 66, 3, 193,
+            147, 16, 145, 65, 49, 33, 53, 247, 69, 47, 44, 113, 86, 117, 6, 20, 193, 183, 128, 178,
+            181, 21, 251, 99, 39, 149, 210, 146, 106, 181, 186, 7, 36, 63, 186, 234, 191, 164, 193,
+            162, 127, 250, 122, 189, 219, 21, 92, 48, 86, 209, 184, 99, 160, 201, 162, 145, 20,
+            138, 154, 18, 37, 180, 209, 165, 165, 51, 187, 78, 193, 175, 135, 6, 55, 216, 178, 10,
+            40, 246, 98, 128, 80, 14, 38, 69, 113, 123, 54, 94, 43, 50, 106, 167, 17, 77, 163, 148,
+            117, 225, 9, 7, 253, 240, 157, 96, 103, 33, 100, 37, 37, 20, 53, 138, 234, 55, 45, 232,
+            154, 9, 150, 192, 116, 36, 119, 106, 95, 119, 34, 220, 84, 174, 19, 227, 33, 209, 96,
+            197, 148, 230, 197, 59, 117, 130, 7, 116, 11, 0, 197, 16, 249, 151, 31, 4, 64, 29, 165,
+            247, 110, 176, 166, 4, 112, 136, 101, 208, 7, 179, 38, 183, 134, 58, 107, 207, 160, 38,
+            159, 67, 112, 20, 225, 199, 179, 133, 117, 144, 54, 199, 15, 204, 80, 154, 116, 84, 88,
+            109, 113, 5, 207, 226, 21, 62, 247, 122, 14, 156, 9, 8, 76, 26, 148, 67, 196, 128, 176,
+            78, 51, 161, 151, 75, 248, 154, 31, 168, 9, 4, 3, 107, 222, 245, 178, 21, 84, 7, 25,
+            155, 118, 97, 135, 63, 89, 233, 11, 207, 148, 155, 38, 106, 104, 102, 140, 104, 67,
+            149, 20, 30, 196, 44, 197, 128, 34, 182, 80, 30, 32, 137, 34, 212, 164, 177, 164, 12,
+            115, 41, 156, 111, 71, 230, 120, 111, 218, 25, 117, 218, 75, 167, 32, 37, 57, 50, 99,
+            181, 203, 40, 105, 248, 150, 114, 121, 73, 127, 198, 191, 161, 44, 56, 213, 243, 71, 2,
+            56, 192, 243, 107, 179, 27, 96, 21, 116, 169, 64, 15, 97, 166, 151, 200, 11, 40, 204,
+            71, 168, 220, 9, 55, 43, 146, 244, 212, 166, 192, 180, 189, 237, 162, 42, 29, 33, 52,
+            193, 4, 178, 157, 244, 28, 209, 44, 26, 36, 147, 126, 94, 164, 37, 47, 115, 38, 23,
+            165, 96, 106, 140, 42, 69, 146, 194, 93, 71, 175, 49, 147, 32, 246, 97, 94, 41, 116,
+            127, 174, 18, 16, 14, 163, 17, 180, 213, 203, 166, 33, 139, 214, 18, 170, 27, 41, 59,
+            175, 200, 101, 14, 128, 45, 179, 167, 136, 232, 138, 56, 124, 145, 75, 233, 132, 161,
+            196, 164, 72, 80, 60, 187, 38, 90, 90, 17, 66, 134, 59, 2, 165, 29, 76, 24, 38, 211,
+            177, 83, 119, 20, 239, 59, 77, 34, 3, 42, 47, 60, 89, 46, 103, 168, 120, 17, 199, 50,
+            17, 103, 107, 48, 8, 53, 220, 159, 212, 65, 198, 80, 8, 11, 235, 97, 203, 196, 240, 44,
+            56, 121, 77, 91, 196, 160, 129, 242, 149, 226, 57, 106, 180, 76, 161, 203, 18, 37, 166,
+            153, 44, 40, 28, 74, 8, 11, 6, 166, 54, 10, 103, 247, 23, 35, 7, 47, 173, 133, 71, 85,
+            3, 168, 250, 120, 126, 174, 37, 80, 128, 107, 7, 161, 130, 155, 136, 92, 48, 215, 119,
+            196, 124, 85, 157, 234, 2, 166, 137, 65, 121, 222, 112, 47, 17, 43, 23, 111, 88, 5,
+            195, 41, 8, 191, 227, 21, 173, 35, 199, 196, 188, 162, 191, 195, 204, 137, 54, 16, 73,
+            178, 150, 249, 234, 22, 216, 123, 157, 144, 218, 118, 53, 193, 67, 65, 84, 162, 244,
+            165, 24, 110, 246, 146, 228, 212, 180, 150, 116, 201, 37, 128, 76, 41, 188, 42, 79,
+            148, 52, 196, 176, 178, 224, 48, 168, 13, 129, 193, 131, 185, 131, 93, 40, 145, 56,
+            180, 29, 153, 83, 39, 69, 232, 96, 238, 137, 104, 150, 2, 202, 239, 149, 248, 154, 115,
+            115, 127, 3, 8, 32, 61, 96, 66, 25, 181, 14, 72, 73, 97, 186, 134, 140, 33, 69, 33, 74,
+        ];
         assert!(expected_ssk == keys.value.0.secret_spending_key);
         assert!(expected_ccc == keys.ccc);
         assert!(expected_nsk == keys.value.0.private_key_holder.nullifier_secret_key);
         assert!(expected_npk == keys.value.0.nullifier_public_key);
-        // vsk is now a 64-byte ML-KEM seed; vpk is a 1184-byte encapsulation key — byte
-        // vectors are asserted non-empty rather than against the old EC point values.
-       // assert!(!keys.value.0.private_key_holder.viewing_secret_key.0.is_empty());
-       // assert!(!keys.value.0.viewing_public_key.0.is_empty());
+        assert!(expected_vsk == keys.value.0.private_key_holder.viewing_secret_key);
+        assert!(expected_vpk == keys.value.0.viewing_public_key.to_bytes());
     }
 
     #[test]
@@ -177,21 +256,112 @@ mod tests {
             114, 39, 38, 118, 197, 205, 225,
         ];
 
+        // Marvin-pq this test currently fails
         let root_node = ChildKeysPrivate::root(seed);
         let child_node = ChildKeysPrivate::nth_child(&root_node, 42_u32);
 
-        let expected_nsk: NullifierSecretKey = [
-            124, 61, 40, 92, 33, 135, 3, 41, 200, 234, 3, 69, 102, 184, 57, 191, 106, 151, 194,
-            192, 103, 132, 141, 112, 249, 108, 192, 117, 24, 48, 70, 216,
-        ];
-        let expected_npk = nssa_core::NullifierPublicKey([
-            116, 231, 246, 189, 145, 240, 37, 59, 219, 223, 216, 246, 116, 171, 223, 55, 197, 200,
-            134, 192, 221, 40, 218, 167, 239, 5, 11, 95, 147, 247, 162, 226,
+        let expected_ssk: SecretSpendingKey = key_management::secret_holders::SecretSpendingKey([
+            215, 207, 70, 52, 161, 220, 88, 88, 241, 149, 81, 130, 217, 214, 252, 170, 51, 232,
+            230, 158, 195, 173, 174, 37, 27, 101, 49, 35, 79, 13, 44, 225,
         ]);
 
+        let expected_ccc = [
+            113, 136, 96, 232, 12, 136, 185, 254, 36, 103, 64, 44, 238, 176, 240, 92, 219, 184,
+            143, 35, 183, 54, 170, 15, 126, 56, 115, 21, 89, 142, 236, 217,
+        ];
+
+        let expected_nsk: NullifierSecretKey = [
+            27, 167, 3, 140, 113, 16, 209, 83, 21, 77, 65, 91, 26, 191, 203, 102, 66, 140, 157,
+            220, 101, 104, 227, 135, 216, 215, 216, 126, 194, 196, 43, 34,
+        ];
+        let expected_npk = nssa_core::NullifierPublicKey([
+            30, 208, 29, 96, 156, 95, 79, 16, 182, 0, 10, 194, 209, 90, 35, 177, 110, 224, 247, 67,
+            219, 114, 113, 16, 42, 27, 220, 96, 151, 124, 8, 65,
+        ]);
+
+        // Marvin-pq double check the d, r labels
+        let expected_vsk: ViewingSecretKey = ViewingSecretKey {
+            d: [
+                81, 154, 68, 152, 72, 163, 82, 17, 125, 156, 193, 135, 129, 93, 227, 55, 224, 104,
+                119, 232, 13, 101, 241, 20, 175, 72, 192, 186, 176, 246, 140, 211,
+            ],
+            r: [
+                31, 40, 109, 41, 185, 61, 173, 79, 102, 171, 158, 245, 232, 71, 57, 157, 142, 117,
+                184, 235, 216, 71, 55, 44, 33, 156, 167, 133, 184, 92, 47, 174,
+            ],
+        };
+
+        let expected_vpk: [u8; 1184] = [
+            67, 150, 145, 133, 41, 124, 194, 102, 104, 131, 195, 8, 168, 170, 200, 40, 210, 84, 85,
+            117, 50, 99, 52, 23, 144, 23, 22, 140, 187, 76, 49, 224, 189, 64, 249, 72, 219, 35, 49,
+            162, 146, 121, 27, 179, 183, 215, 84, 177, 62, 37, 103, 97, 209, 201, 8, 162, 38, 109,
+            87, 44, 103, 136, 112, 236, 120, 60, 235, 130, 60, 212, 209, 77, 77, 220, 28, 156, 34,
+            7, 31, 35, 179, 102, 21, 54, 77, 99, 157, 210, 247, 151, 214, 182, 30, 57, 219, 40, 42,
+            188, 32, 30, 134, 126, 7, 22, 51, 241, 152, 8, 96, 5, 87, 168, 64, 62, 81, 247, 33,
+            228, 44, 180, 203, 60, 49, 66, 247, 143, 113, 106, 189, 44, 11, 182, 213, 247, 9, 22,
+            3, 208, 125, 2, 8, 103, 195, 202, 21, 33, 72, 139, 233, 19, 171, 172, 69, 253, 212, 37,
+            197, 66, 165, 207, 168, 69, 18, 24, 1, 100, 200, 175, 163, 247, 115, 17, 124, 84, 183,
+            92, 96, 142, 204, 149, 2, 90, 53, 110, 246, 188, 135, 240, 160, 231, 145, 23, 90, 209,
+            93, 166, 17, 119, 240, 49, 67, 234, 41, 187, 71, 23, 152, 159, 54, 206, 207, 26, 11,
+            32, 134, 202, 185, 201, 25, 59, 199, 182, 18, 236, 175, 254, 227, 195, 98, 52, 139,
+            162, 172, 195, 102, 178, 115, 59, 113, 108, 96, 89, 175, 145, 71, 202, 231, 153, 69, 3,
+            25, 60, 43, 215, 35, 70, 119, 16, 235, 98, 184, 252, 50, 36, 161, 244, 57, 13, 214,
+            115, 106, 225, 166, 7, 59, 44, 130, 197, 85, 69, 220, 81, 10, 1, 130, 227, 225, 47, 78,
+            251, 49, 232, 55, 2, 66, 64, 180, 220, 65, 140, 231, 188, 172, 153, 153, 152, 15, 186,
+            74, 6, 39, 16, 251, 216, 165, 145, 134, 3, 88, 131, 80, 114, 156, 119, 72, 130, 54,
+            159, 202, 23, 7, 130, 127, 156, 252, 113, 108, 85, 22, 120, 104, 12, 151, 187, 102, 64,
+            96, 137, 184, 68, 201, 20, 196, 196, 226, 220, 139, 174, 76, 109, 1, 179, 81, 156, 26,
+            136, 238, 106, 41, 197, 18, 16, 179, 91, 9, 8, 213, 123, 108, 58, 3, 102, 12, 87, 92,
+            217, 207, 166, 131, 17, 218, 134, 170, 27, 129, 145, 0, 65, 85, 99, 163, 97, 78, 228,
+            15, 54, 85, 201, 58, 204, 160, 250, 66, 41, 36, 165, 78, 50, 137, 78, 197, 103, 57, 79,
+            26, 14, 167, 104, 165, 129, 128, 90, 104, 148, 121, 135, 24, 126, 139, 235, 84, 183,
+            165, 115, 111, 83, 48, 184, 55, 84, 250, 115, 171, 195, 91, 114, 213, 104, 51, 110, 86,
+            148, 37, 139, 83, 49, 165, 171, 144, 90, 19, 91, 195, 111, 82, 185, 133, 211, 24, 186,
+            48, 230, 172, 190, 6, 65, 230, 26, 139, 8, 9, 34, 54, 28, 103, 84, 116, 38, 252, 105,
+            86, 123, 40, 31, 39, 64, 14, 253, 215, 147, 182, 218, 111, 148, 2, 18, 3, 197, 4, 129,
+            107, 136, 89, 122, 56, 47, 9, 179, 66, 227, 24, 193, 32, 4, 172, 210, 29, 152, 114,
+            134, 65, 249, 201, 178, 16, 206, 209, 39, 193, 109, 91, 122, 194, 26, 206, 37, 227, 55,
+            160, 214, 85, 196, 64, 97, 96, 66, 80, 34, 177, 83, 200, 44, 137, 175, 149, 114, 42,
+            229, 168, 248, 96, 106, 110, 182, 155, 62, 27, 179, 229, 139, 9, 213, 181, 116, 59,
+            118, 142, 91, 23, 165, 80, 43, 118, 18, 41, 143, 125, 59, 102, 61, 224, 120, 186, 10,
+            63, 119, 241, 168, 196, 87, 117, 138, 3, 151, 1, 129, 76, 154, 87, 200, 114, 124, 90,
+            212, 182, 54, 94, 20, 165, 243, 88, 77, 76, 152, 69, 19, 164, 106, 196, 204, 46, 239,
+            116, 42, 179, 65, 79, 39, 145, 63, 169, 199, 142, 6, 103, 118, 130, 49, 184, 208, 203,
+            36, 162, 216, 9, 188, 17, 86, 45, 35, 20, 178, 218, 121, 164, 243, 145, 57, 208, 130,
+            26, 27, 28, 100, 161, 148, 195, 54, 66, 114, 108, 146, 135, 66, 69, 232, 33, 197, 213,
+            131, 107, 31, 19, 162, 155, 164, 161, 103, 8, 192, 127, 188, 196, 252, 2, 155, 18, 130,
+            105, 53, 235, 200, 87, 203, 162, 95, 50, 158, 96, 210, 1, 45, 8, 26, 3, 192, 201, 182,
+            148, 192, 157, 106, 5, 161, 248, 66, 89, 56, 141, 126, 243, 143, 68, 90, 133, 193, 181,
+            198, 3, 169, 72, 66, 215, 195, 38, 37, 196, 103, 229, 89, 162, 210, 118, 12, 233, 162,
+            95, 164, 107, 97, 11, 120, 255, 164, 60, 117, 37, 108, 144, 185, 167, 40, 124, 69, 23,
+            37, 148, 222, 233, 43, 50, 16, 58, 53, 252, 8, 102, 88, 109, 28, 18, 22, 5, 49, 66,
+            149, 114, 203, 95, 216, 175, 10, 87, 206, 46, 9, 101, 212, 226, 84, 4, 231, 161, 106,
+            185, 31, 6, 101, 27, 54, 49, 85, 54, 84, 12, 250, 4, 49, 184, 134, 186, 23, 146, 54,
+            90, 186, 134, 129, 68, 10, 241, 201, 65, 251, 69, 110, 127, 220, 148, 38, 250, 148, 83,
+            32, 100, 131, 83, 133, 195, 54, 132, 63, 229, 85, 34, 172, 126, 68, 99, 197, 18, 197,
+            91, 221, 234, 66, 203, 156, 73, 46, 0, 54, 205, 11, 52, 172, 114, 193, 127, 171, 134,
+            109, 92, 37, 124, 181, 167, 191, 209, 148, 232, 26, 136, 230, 133, 181, 248, 117, 11,
+            45, 156, 136, 117, 144, 126, 239, 230, 144, 90, 57, 109, 158, 167, 19, 131, 215, 136,
+            85, 136, 10, 49, 9, 146, 64, 81, 28, 171, 53, 78, 40, 225, 94, 238, 70, 174, 125, 186,
+            155, 177, 202, 157, 63, 39, 152, 44, 105, 184, 140, 179, 204, 32, 210, 109, 35, 150,
+            194, 14, 98, 148, 176, 73, 185, 49, 135, 135, 244, 151, 147, 17, 103, 35, 242, 130, 3,
+            158, 198, 152, 83, 240, 198, 254, 145, 181, 67, 163, 14, 237, 249, 179, 252, 220, 67,
+            239, 7, 118, 131, 229, 137, 172, 151, 57, 121, 138, 204, 6, 208, 52, 168, 236, 123,
+            104, 68, 36, 141, 25, 168, 56, 199, 40, 200, 52, 97, 59, 55, 184, 196, 234, 204, 108,
+            75, 65, 177, 82, 207, 127, 128, 157, 0, 68, 163, 127, 152, 85, 123, 209, 163, 21, 119,
+            62, 250, 236, 58, 229, 220, 99, 209, 147, 10, 177, 115, 172, 96, 192, 80, 240, 66, 191,
+            138, 91, 52, 200, 132, 126, 255, 69, 98, 12, 140, 8, 158, 2, 153, 66, 211, 74, 242,
+            147, 148, 209, 6, 161, 76, 149, 158, 209, 163, 20, 76, 75, 192, 193, 162, 71, 134, 72,
+            160, 192, 10, 203, 4, 213, 23, 140, 196, 39, 231, 39, 16, 209, 228, 112, 244, 29, 27,
+            181, 190, 19, 134, 116, 173, 135, 190, 118, 4, 214, 194, 189, 224, 164, 91, 211, 182,
+            162, 226,
+        ];
+
+        assert!(expected_ssk == child_node.value.0.secret_spending_key);
+        assert!(expected_ccc == child_node.ccc);
         assert!(expected_nsk == child_node.value.0.private_key_holder.nullifier_secret_key);
         assert!(expected_npk == child_node.value.0.nullifier_public_key);
-       // assert!(!child_node.value.0.private_key_holder.viewing_secret_key.0.is_empty());
-       // assert!(!child_node.value.0.viewing_public_key.0.is_empty());
+        assert!(expected_vsk == child_node.value.0.private_key_holder.viewing_secret_key);
+        assert!(expected_vpk == child_node.value.0.viewing_public_key.to_bytes());
     }
 }
diff --git a/key_protocol/src/key_management/mod.rs b/key_protocol/src/key_management/mod.rs
index 676a90aa..58655578 100644
--- a/key_protocol/src/key_management/mod.rs
+++ b/key_protocol/src/key_management/mod.rs
@@ -1,6 +1,6 @@
 use nssa_core::{
     NullifierPublicKey, SharedSecretKey,
-    encryption::{EphemeralPublicKey, ViewingPublicKey, Scalar},
+    encryption::{EphemeralPublicKey, ViewingPublicKey},
 };
 use secret_holders::{PrivateKeyHolder, SecretSpendingKey, SeedHolder};
 use serde::{Deserialize, Serialize};
@@ -71,19 +71,14 @@ impl KeyChain {
         ephemeral_public_key_sender: &EphemeralPublicKey,
         _index: Option<u32>,
     ) -> SharedSecretKey {
-        SharedSecretKey::new(
-            &Scalar::default(),
-            ephemeral_public_key_sender,
-        )
+        let vsk = &self.private_key_holder.viewing_secret_key;
+        SharedSecretKey::decapsulate(ephemeral_public_key_sender, &vsk.d, &vsk.r)
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use aes_gcm::aead::OsRng;
     use base58::ToBase58 as _;
-    use k256::{AffinePoint, elliptic_curve::group::GroupEncoding as _};
-    use rand::RngCore as _;
 
     use super::*;
     use crate::key_management::{
@@ -106,14 +101,10 @@ mod tests {
     fn calculate_shared_secret_receiver() {
         let account_id_key_holder = KeyChain::new_os_random();
 
-        // Generate a random ephemeral public key sender
-        let mut scalar = [0; 32];
-        OsRng.fill_bytes(&mut scalar);
-        let ephemeral_public_key_sender = EphemeralPublicKey::from_scalar(scalar);
+        // Create a proper KEM ciphertext by encapsulating toward this key chain's VPK.
+        let (_, epk) = SharedSecretKey::encapsulate(&account_id_key_holder.viewing_public_key);
 
-        // Calculate shared secret
-        let _shared_secret = account_id_key_holder
-            .calculate_shared_secret_receiver(&ephemeral_public_key_sender, None);
+        let _shared_secret = account_id_key_holder.calculate_shared_secret_receiver(&epk, None);
     }
 
     #[test]
@@ -135,12 +126,6 @@ mod tests {
         println!("======Prerequisites======");
         println!();
 
-        println!(
-            "Group generator {:?}",
-            hex::encode(AffinePoint::GENERATOR.to_bytes())
-        );
-        println!();
-
         println!("======Holders======");
         println!();
 
@@ -188,13 +173,11 @@ mod tests {
     fn non_trivial_chain_index() {
         let keys = account_with_chain_index_2_for_tests();
 
-        let eph_key_holder = EphemeralKeyHolder::new(&keys.nullifier_public_key);
+        let eph_key_holder = EphemeralKeyHolder::new(&keys.viewing_public_key);
 
-        let key_sender = eph_key_holder.calculate_shared_secret_sender(&keys.viewing_public_key);
-        let key_receiver = keys.calculate_shared_secret_receiver(
-            &eph_key_holder.generate_ephemeral_public_key(),
-            Some(2),
-        );
+        let key_sender = eph_key_holder.calculate_shared_secret_sender();
+        let key_receiver =
+            keys.calculate_shared_secret_receiver(eph_key_holder.ephemeral_public_key(), Some(2));
 
         assert_eq!(key_sender.0, key_receiver.0);
     }
diff --git a/key_protocol/src/key_management/secret_holders.rs b/key_protocol/src/key_management/secret_holders.rs
index 7fae51cb..49592b75 100644
--- a/key_protocol/src/key_management/secret_holders.rs
+++ b/key_protocol/src/key_management/secret_holders.rs
@@ -1,10 +1,7 @@
 use bip39::Mnemonic;
 use common::HashType;
 use ml_kem;
-use nssa_core::{
-    NullifierPublicKey, NullifierSecretKey,
-    encryption::ViewingPublicKey,
-};
+use nssa_core::{NullifierPublicKey, NullifierSecretKey, encryption::ViewingPublicKey};
 use rand::{RngCore as _, rngs::OsRng};
 use serde::{Deserialize, Serialize};
 use sha2::{Digest as _, digest::FixedOutput as _};
@@ -120,7 +117,7 @@ impl SecretSpendingKey {
 
     #[must_use]
     #[expect(clippy::big_endian_bytes, reason = "BIP-032 uses big endian")]
-    pub fn generate_viewing_secret_seed_key(&self, index: Option<u32>) -> [u8; 64] {
+    pub fn generate_viewing_secret_seed_key(&self, index: Option<u32>) -> ViewingSecretKey {
         const PREFIX: &[u8; 8] = b"LEE/keys";
         const SUFFIX_1: &[u8; 1] = &[2];
         const SUFFIX_2: &[u8; 19] = &[0; 19];
@@ -136,9 +133,20 @@ impl SecretSpendingKey {
         bytes.extend_from_slice(SUFFIX_1);
         bytes.extend_from_slice(&index.to_be_bytes());
         bytes.extend_from_slice(SUFFIX_2);
-        let bytes: [u8; 64] = bytes.try_into().expect("`generate_viewing_secret_key`: bytes must be exactly 64");
+        let bytes: [u8; 64] = bytes
+            .try_into()
+            .expect("`generate_viewing_secret_key`: bytes must be exactly 64");
 
-        hmac_sha512::HMAC::mac(bytes, b"LEE_viewing_seed")
+        let full_seed = hmac_sha512::HMAC::mac(bytes, b"LEE_viewing_seed");
+
+        ViewingSecretKey {
+            d: *full_seed
+                .first_chunk::<32>()
+                .expect("hash_value is 64 bytes, must be safe to get first 32"),
+            r: *full_seed
+                .last_chunk::<32>()
+                .expect("hash_value is 64 bytes, must be safe to get last 32"),
+        }
     }
 
     #[must_use]
@@ -153,9 +161,7 @@ impl SecretSpendingKey {
     pub fn produce_private_key_holder(&self, index: Option<u32>) -> PrivateKeyHolder {
         PrivateKeyHolder {
             nullifier_secret_key: self.generate_nullifier_secret_key(index),
-            viewing_secret_key: Self::generate_viewing_secret_key(
-                self.generate_viewing_secret_seed_key(index),
-            ),
+            viewing_secret_key: self.generate_viewing_secret_seed_key(index),
         }
     }
 }
@@ -211,10 +217,8 @@ mod tests {
         assert_eq!(seed_holder.seed.len(), 64);
 
         let top_secret_key_holder = seed_holder.produce_top_secret_key_holder();
-
-        let _vsk = SecretSpendingKey::generate_viewing_secret_key(
-            top_secret_key_holder.generate_viewing_secret_seed_key(None),
-        );
+        // Marvin-pq should drop seed from the fucntion name
+        let _vsk = top_secret_key_holder.generate_viewing_secret_seed_key(None);
     }
 
     #[test]
diff --git a/key_protocol/src/key_protocol_core/mod.rs b/key_protocol/src/key_protocol_core/mod.rs
index e973655e..d4747d39 100644
--- a/key_protocol/src/key_protocol_core/mod.rs
+++ b/key_protocol/src/key_protocol_core/mod.rs
@@ -55,7 +55,7 @@ pub struct NSSAUserData {
     /// Dedicated sealing secret key for GMS distribution. Generated once via
     /// `wallet group new-sealing-key`. The corresponding public key is shared with
     /// group members so they can seal GMS for this wallet.
-    pub sealing_secret_key: Option<nssa_core::encryption::Scalar>,
+    pub sealing_secret_key: Option<crate::key_management::secret_holders::ViewingSecretKey>,
 }
 
 impl NSSAUserData {
diff --git a/nssa/core/Cargo.toml b/nssa/core/Cargo.toml
index d9e80af4..3a26e99d 100644
--- a/nssa/core/Cargo.toml
+++ b/nssa/core/Cargo.toml
@@ -17,6 +17,7 @@ bytemuck.workspace = true
 bytesize.workspace = true
 base58.workspace = true
 k256 = { workspace = true, optional = true }
+ml-kem = { workspace = true, optional = true, features = ["getrandom"] }
 chacha20 = { version = "0.10" }
 
 [dev-dependencies]
@@ -24,4 +25,4 @@ serde_json.workspace = true
 
 [features]
 default = []
-host = ["dep:k256"]
+host = ["dep:k256", "dep:ml-kem"]
diff --git a/nssa/core/src/encoding.rs b/nssa/core/src/encoding.rs
index ac9317c2..354169a8 100644
--- a/nssa/core/src/encoding.rs
+++ b/nssa/core/src/encoding.rs
@@ -7,7 +7,7 @@ use std::io::Read as _;
 #[cfg(feature = "host")]
 use crate::Nullifier;
 #[cfg(feature = "host")]
-use crate::encryption::shared_key_derivation::Secp256k1Point;
+use crate::encryption::{EphemeralPublicKey, shared_key_derivation::Secp256k1Point};
 #[cfg(feature = "host")]
 use crate::error::NssaCoreError;
 use crate::{
@@ -173,6 +173,26 @@ impl Secp256k1Point {
     }
 }
 
+// Marvin-pq: EphemeralPublicKey is now the ML-KEM-768 ciphertext (1088 bytes) produced by
+// SharedSecretKey::encapsulate.  It replaces the old Secp256k1Point (33 bytes) on the wire.
+// Fixed size: 1088 bytes for ML-KEM-768 (EncodedUSize + EncodedVSize per FIPS 203 §7.2).
+#[cfg(feature = "host")]
+impl EphemeralPublicKey {
+    /// Serializes the ML-KEM-768 ciphertext to bytes (always 1088 bytes).
+    #[must_use]
+    pub fn to_bytes(&self) -> Vec<u8> {
+        self.0.clone()
+    }
+
+    /// Deserializes an ML-KEM-768 ciphertext from a cursor.
+    /// Reads exactly 1088 bytes — the fixed ciphertext size for ML-KEM-768.
+    pub fn from_cursor(cursor: &mut Cursor<&[u8]>) -> Result<Self, NssaCoreError> {
+        let mut value = vec![0u8; 1088];
+        cursor.read_exact(&mut value)?;
+        Ok(Self(value))
+    }
+}
+
 impl AccountId {
     #[must_use]
     pub const fn to_bytes(&self) -> [u8; 32] {
diff --git a/nssa/core/src/encryption/mod.rs b/nssa/core/src/encryption/mod.rs
index 4b675d0e..0c44fef6 100644
--- a/nssa/core/src/encryption/mod.rs
+++ b/nssa/core/src/encryption/mod.rs
@@ -6,7 +6,7 @@ use chacha20::{
 use risc0_zkvm::sha::{Impl, Sha256 as _};
 use serde::{Deserialize, Serialize};
 #[cfg(feature = "host")]
-pub use shared_key_derivation::{EphemeralPublicKey, EphemeralSecretKey, ViewingPublicKey};
+pub use shared_key_derivation::{EphemeralPublicKey, ViewingPublicKey};
 
 use crate::{Commitment, account::Account, program::PrivateAccountKind};
 #[cfg(feature = "host")]
diff --git a/nssa/core/src/encryption/shared_key_derivation.rs b/nssa/core/src/encryption/shared_key_derivation.rs
index d1022399..44607ea5 100644
--- a/nssa/core/src/encryption/shared_key_derivation.rs
+++ b/nssa/core/src/encryption/shared_key_derivation.rs
@@ -7,16 +7,16 @@ use std::fmt::Write as _;
 
 use borsh::{BorshDeserialize, BorshSerialize};
 use k256::{
-    AffinePoint, EncodedPoint, FieldBytes, ProjectivePoint,
-    elliptic_curve::{
-        PrimeField as _,
-        sec1::{FromEncodedPoint as _, ToEncodedPoint as _},
-    },
+    AffinePoint, FieldBytes, ProjectivePoint,
+    elliptic_curve::{PrimeField as _, sec1::ToEncodedPoint as _},
 };
+use ml_kem::{Decapsulate as _, Encapsulate as _, KeyExport as _, Seed};
 use serde::{Deserialize, Serialize};
 
 use crate::{SharedSecretKey, encryption::Scalar};
 
+/// A compressed secp256k1 point (33 bytes).
+/// Kept for backward compatibility with Phase-2+ callers; no longer used as `EphemeralPublicKey`.
 #[derive(Serialize, Deserialize, Clone, PartialEq, Eq, BorshSerialize, BorshDeserialize)]
 pub struct Secp256k1Point(pub Vec<u8>);
 
@@ -44,10 +44,12 @@ impl Secp256k1Point {
     }
 }
 
-pub type EphemeralSecretKey = Scalar;
-pub type EphemeralPublicKey = Secp256k1Point;
+/// The ML-KEM-768 ciphertext produced during encapsulation; transmitted on-wire in place of the
+/// former ECDH ephemeral public key.  Always 1088 bytes for ML-KEM-768.
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq, BorshSerialize, BorshDeserialize)]
+pub struct EphemeralPublicKey(pub Vec<u8>);
 
-/// ML-KEM 768 encapsulation key bytes (1184 bytes, opaque to this crate).
+/// ML-KEM-768 encapsulation key bytes (1184 bytes, opaque to this crate).
 #[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq, BorshSerialize, BorshDeserialize)]
 pub struct ViewingPublicKey(pub Vec<u8>);
 
@@ -56,35 +58,153 @@ impl ViewingPublicKey {
     pub fn to_bytes(&self) -> &[u8] {
         &self.0
     }
-}
 
-impl From<&EphemeralSecretKey> for EphemeralPublicKey {
-    fn from(value: &EphemeralSecretKey) -> Self {
-        Self::from_scalar(*value)
+    /// Derive the ML-KEM-768 encapsulation key from the FIPS 203 seed halves `d` and `r`.
+    /// Allows any crate to construct a VPK from raw seed bytes without importing
+    /// `key_protocol::ViewingSecretKey`.
+    #[must_use]
+    pub fn from_seed(d: &[u8; 32], r: &[u8; 32]) -> Self {
+        let mut seed = Seed::default();
+        seed[..32].copy_from_slice(d);
+        seed[32..].copy_from_slice(r);
+        let dk = ml_kem::DecapsulationKey768::from_seed(seed);
+        Self(dk.encapsulation_key().to_bytes().to_vec())
     }
 }
 
 impl SharedSecretKey {
-    /// Creates a new shared secret key from a scalar and a point.
+    /// Sender: encapsulate a fresh shared secret toward `vpk`.
+    ///
+    /// Returns `(shared_secret, ciphertext)`.  The ciphertext must be included in the transaction
+    /// as the `EphemeralPublicKey`; the receiver recovers the same shared secret via
+    /// [`decapsulate`][Self::decapsulate].
     #[must_use]
-    pub fn new(_scalar: &[u8; 32], _point: &Secp256k1Point) -> Self {
-        let scalar = &Scalar::default();
-        let point = &Secp256k1Point::from_scalar(*scalar);
+    pub fn encapsulate(vpk: &ViewingPublicKey) -> (Self, EphemeralPublicKey) {
+        let ek_bytes: ml_kem::kem::Key<ml_kem::EncapsulationKey768> = vpk
+            .0
+            .as_slice()
+            .try_into()
+            .expect("ViewingPublicKey must be 1184 bytes (ML-KEM-768 encapsulation key)");
+        let ek = ml_kem::EncapsulationKey768::new(&ek_bytes)
+            .expect("ViewingPublicKey bytes must encode a valid ML-KEM-768 encapsulation key");
+        let (ct, ss) = ek.encapsulate();
+        let ss_bytes: [u8; 32] = ss
+            .as_slice()
+            .try_into()
+            .expect("ML-KEM shared key is 32 bytes");
+        (Self(ss_bytes), EphemeralPublicKey(ct.to_vec()))
+    }
 
-        let scalar = k256::Scalar::from_repr((*scalar).into()).unwrap();
-        let point: [u8; 33] = point.0.clone().try_into().unwrap();
+    /// Sender: deterministically encapsulate a shared secret toward `vpk`.
+    ///
+    /// The KEM randomness is derived as `SHA-256(message_hash || output_index_le)`,
+    /// making the ciphertext reproducible from the same `(vpk, message_hash, output_index)`
+    /// triple. Use a distinct `output_index` for each private account output in the same
+    /// transaction to ensure per-output EPK uniqueness.
+    #[must_use]
+    pub fn encapsulate_deterministic(
+        vpk: &ViewingPublicKey,
+        message_hash: &[u8; 32],
+        output_index: u32,
+    ) -> (Self, EphemeralPublicKey) {
+        use risc0_zkvm::sha::{Impl, Sha256 as _};
 
-        let encoded = EncodedPoint::from_bytes(point).unwrap();
-        let pubkey_affine = AffinePoint::from_encoded_point(&encoded).unwrap();
+        let mut input = Vec::with_capacity(36);
+        input.extend_from_slice(message_hash);
+        input.extend_from_slice(&output_index.to_le_bytes());
+        let hash = Impl::hash_bytes(&input);
+        let m: ml_kem::B32 = ml_kem::array::Array::try_from(hash.as_bytes() as &[u8])
+            .expect("SHA-256 output is 32 bytes");
 
-        let shared = ProjectivePoint::from(pubkey_affine) * scalar;
-        let shared_affine = shared.to_affine();
+        let ek_bytes: ml_kem::kem::Key<ml_kem::EncapsulationKey768> = vpk
+            .0
+            .as_slice()
+            .try_into()
+            .expect("ViewingPublicKey must be 1184 bytes (ML-KEM-768 encapsulation key)");
+        let ek = ml_kem::EncapsulationKey768::new(&ek_bytes)
+            .expect("ViewingPublicKey bytes must encode a valid ML-KEM-768 encapsulation key");
+        let (ct, ss) = ek.encapsulate_deterministic(&m);
+        let ss_bytes: [u8; 32] = ss
+            .as_slice()
+            .try_into()
+            .expect("ML-KEM shared key is 32 bytes");
+        (Self(ss_bytes), EphemeralPublicKey(ct.to_vec()))
+    }
 
-        let shared_affine_encoded = shared_affine.to_encoded_point(false);
-        let x_bytes_slice = shared_affine_encoded.x().unwrap();
-        let mut x_bytes = [0_u8; 32];
-        x_bytes.copy_from_slice(x_bytes_slice);
-
-        Self(x_bytes)
+    /// Receiver: decapsulate the shared secret from a KEM ciphertext.
+    ///
+    /// `d` and `r` are the two 32-byte halves of the FIPS 203 `ViewingSecretKey` seed.
+    #[must_use]
+    pub fn decapsulate(ciphertext: &EphemeralPublicKey, d: &[u8; 32], r: &[u8; 32]) -> Self {
+        let mut seed = Seed::default();
+        seed[..32].copy_from_slice(d);
+        seed[32..].copy_from_slice(r);
+        let dk = ml_kem::DecapsulationKey768::from_seed(seed);
+        let ss = dk
+            .decapsulate_slice(&ciphertext.0)
+            .expect("EphemeralPublicKey must be 1088 bytes (ML-KEM-768 ciphertext)");
+        let ss_bytes: [u8; 32] = ss
+            .as_slice()
+            .try_into()
+            .expect("ML-KEM shared key is 32 bytes");
+        Self(ss_bytes)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use ml_kem::KeyExport as _;
+
+    use super::*;
+
+    #[test]
+    fn encapsulate_decapsulate_round_trip() {
+        let d = [1u8; 32];
+        let r = [2u8; 32];
+
+        let mut seed = Seed::default();
+        seed[..32].copy_from_slice(&d);
+        seed[32..].copy_from_slice(&r);
+
+        let dk = ml_kem::DecapsulationKey768::from_seed(seed);
+        let ek_bytes = dk.encapsulation_key().to_bytes();
+        let vpk = ViewingPublicKey(ek_bytes.to_vec());
+
+        let (sender_ss, epk) = SharedSecretKey::encapsulate(&vpk);
+        let receiver_ss = SharedSecretKey::decapsulate(&epk, &d, &r);
+
+        assert_eq!(sender_ss.0, receiver_ss.0, "shared secrets must match");
+        assert_eq!(epk.0.len(), 1088, "ML-KEM-768 ciphertext is 1088 bytes");
+        assert_eq!(
+            vpk.0.len(),
+            1184,
+            "ML-KEM-768 encapsulation key is 1184 bytes"
+        );
+    }
+
+    #[test]
+    fn different_vpks_produce_different_shared_secrets() {
+        let (d1, r1) = ([1u8; 32], [2u8; 32]);
+        let (d2, r2) = ([3u8; 32], [4u8; 32]);
+
+        let vpk1 = {
+            let mut seed = Seed::default();
+            seed[..32].copy_from_slice(&d1);
+            seed[32..].copy_from_slice(&r1);
+            let dk = ml_kem::DecapsulationKey768::from_seed(seed);
+            ViewingPublicKey(dk.encapsulation_key().to_bytes().to_vec())
+        };
+        let vpk2 = {
+            let mut seed = Seed::default();
+            seed[..32].copy_from_slice(&d2);
+            seed[32..].copy_from_slice(&r2);
+            let dk = ml_kem::DecapsulationKey768::from_seed(seed);
+            ViewingPublicKey(dk.encapsulation_key().to_bytes().to_vec())
+        };
+
+        let (ss1, _) = SharedSecretKey::encapsulate(&vpk1);
+        let (ss2, _) = SharedSecretKey::encapsulate(&vpk2);
+
+        assert_ne!(ss1.0, ss2.0);
     }
 }
diff --git a/nssa/src/privacy_preserving_transaction/circuit.rs b/nssa/src/privacy_preserving_transaction/circuit.rs
index 09e37664..27cfd9b4 100644
--- a/nssa/src/privacy_preserving_transaction/circuit.rs
+++ b/nssa/src/privacy_preserving_transaction/circuit.rs
@@ -243,8 +243,8 @@ mod tests {
 
         let expected_sender_pre = sender.clone();
 
-        let esk = [3; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &recipient_keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&recipient_keys.vpk(), &[0u8; 32], 0).0;
 
         let (output, proof) = execute_and_prove(
             vec![sender, recipient],
@@ -337,11 +337,11 @@ mod tests {
             Commitment::new(&recipient_account_id, &expected_private_account_2),
         ];
 
-        let esk_1 = [3; 32];
-        let shared_secret_1 = SharedSecretKey::new(&esk_1, &sender_keys.vpk());
+        let shared_secret_1 =
+            SharedSecretKey::encapsulate_deterministic(&sender_keys.vpk(), &[0u8; 32], 0).0;
 
-        let esk_2 = [5; 32];
-        let shared_secret_2 = SharedSecretKey::new(&esk_2, &recipient_keys.vpk());
+        let shared_secret_2 =
+            SharedSecretKey::encapsulate_deterministic(&recipient_keys.vpk(), &[0u8; 32], 1).0;
 
         let (output, proof) = execute_and_prove(
             vec![sender_pre, recipient],
@@ -412,8 +412,8 @@ mod tests {
         ))
         .unwrap();
 
-        let esk = [3; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &account_keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&account_keys.vpk(), &[0u8; 32], 0).0;
 
         let program_with_deps = ProgramWithDependencies::new(
             validity_window_chain_caller,
@@ -443,7 +443,8 @@ mod tests {
         let npk = keys.npk();
         let seed = PdaSeed::new([42; 32]);
         let identifier: u128 = 99;
-        let shared_secret = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         let account_id = AccountId::for_private_pda(&program.id(), &seed, &npk, identifier);
         let pre_state = AccountWithMetadata::new(Account::default(), false, account_id);
@@ -480,7 +481,8 @@ mod tests {
         let keys = test_private_account_keys_1();
         let npk = keys.npk();
         let seed = PdaSeed::new([42; 32]);
-        let shared_secret_pda = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let shared_secret_pda =
+            SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         // PDA (new, mask 3)
         let pda_id = AccountId::for_private_pda(&program.id(), &seed, &npk, 0);
@@ -518,7 +520,8 @@ mod tests {
         let keys = test_private_account_keys_1();
         let npk = keys.npk();
         let seed = PdaSeed::new([42; 32]);
-        let shared_secret_pda = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let shared_secret_pda =
+            SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         // PDA (new, private PDA)
         let pda_id = AccountId::for_private_pda(&program.id(), &seed, &npk, 0);
@@ -572,7 +575,8 @@ mod tests {
         let shared_keys = test_private_account_keys_1();
         let shared_npk = shared_keys.npk();
         let shared_identifier: u128 = 42;
-        let shared_secret = SharedSecretKey::new(&[55; 32], &shared_keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&shared_keys.vpk(), &[0u8; 32], 0).0;
 
         // Sender: public account with balance, owned by auth-transfer
         let sender_id = AccountId::new([99; 32]);
@@ -619,7 +623,7 @@ mod tests {
         let program = Program::authenticated_transfer_program();
         let keys = test_private_account_keys_1();
         let identifier: u128 = 99;
-        let ssk = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let ssk = SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
         let account_id = AccountId::for_regular_private_account(&keys.npk(), identifier);
         let pre = AccountWithMetadata::new(Account::default(), true, account_id);
 
@@ -648,7 +652,7 @@ mod tests {
         let program = Program::authenticated_transfer_program();
         let keys = test_private_account_keys_1();
         let identifier: u128 = 99;
-        let ssk = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let ssk = SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         let sender = AccountWithMetadata::new(
             Account {
@@ -690,7 +694,7 @@ mod tests {
         let program = Program::authenticated_transfer_program();
         let keys = test_private_account_keys_1();
         let identifier: u128 = 99;
-        let ssk = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let ssk = SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
         let account_id = AccountId::for_regular_private_account(&keys.npk(), identifier);
         let account = Account {
             program_owner: program.id(),
@@ -736,7 +740,7 @@ mod tests {
         let npk = keys.npk();
         let seed = PdaSeed::new([42; 32]);
         let identifier: u128 = 99;
-        let ssk = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let ssk = SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         let auth_transfer_id = auth_transfer.id();
         let pda_id = AccountId::for_private_pda(&program.id(), &seed, &npk, identifier);
@@ -790,7 +794,8 @@ mod tests {
         let keys = test_private_account_keys_1();
         let npk = keys.npk();
         let seed = PdaSeed::new([42; 32]);
-        let shared_secret = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         let account_id = AccountId::for_private_pda(&program.id(), &seed, &npk, 5);
         let pre_state = AccountWithMetadata::new(Account::default(), false, account_id);
@@ -816,7 +821,7 @@ mod tests {
         let keys = test_private_account_keys_1();
         let npk = keys.npk();
         let seed = PdaSeed::new([42; 32]);
-        let ssk = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let ssk = SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         let auth_transfer_id = auth_transfer.id();
         let pda_id = AccountId::for_private_pda(&program.id(), &seed, &npk, 5);
diff --git a/nssa/src/privacy_preserving_transaction/message.rs b/nssa/src/privacy_preserving_transaction/message.rs
index d86273d8..97643cd1 100644
--- a/nssa/src/privacy_preserving_transaction/message.rs
+++ b/nssa/src/privacy_preserving_transaction/message.rs
@@ -143,7 +143,7 @@ pub mod tests {
         Commitment, EncryptionScheme, Nullifier, NullifierPublicKey, PrivateAccountKind,
         SharedSecretKey,
         account::{Account, AccountId, Nonce},
-        encryption::{EphemeralPublicKey, ViewingPublicKey},
+        encryption::ViewingPublicKey,
         program::{BlockValidityWindow, TimestampValidityWindow},
     };
     use sha2::{Digest as _, Sha256};
@@ -246,13 +246,11 @@ pub mod tests {
     #[test]
     fn encrypted_account_data_constructor() {
         let npk = NullifierPublicKey::from(&[1; 32]);
-        let vpk = ViewingPublicKey::from_scalar([2; 32]);
+        let vpk = ViewingPublicKey::from_seed(&[2u8; 32], &[3u8; 32]);
         let account = Account::default();
         let account_id = nssa_core::account::AccountId::for_regular_private_account(&npk, 0);
         let commitment = Commitment::new(&account_id, &account);
-        let esk = [3; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &vpk);
-        let epk = EphemeralPublicKey::from_scalar(esk);
+        let (shared_secret, epk) = SharedSecretKey::encapsulate_deterministic(&vpk, &[0u8; 32], 0);
         let ciphertext = EncryptionScheme::encrypt(
             &account,
             &PrivateAccountKind::Regular(0),
diff --git a/nssa/src/state.rs b/nssa/src/state.rs
index 8cf1d68e..4ab7ff87 100644
--- a/nssa/src/state.rs
+++ b/nssa/src/state.rs
@@ -365,7 +365,7 @@ pub mod tests {
         BlockId, Commitment, InputAccountIdentity, Nullifier, NullifierPublicKey,
         NullifierSecretKey, SharedSecretKey, Timestamp,
         account::{Account, AccountId, AccountWithMetadata, Nonce, data::Data},
-        encryption::{EphemeralPublicKey, Scalar, ViewingPublicKey},
+        encryption::ViewingPublicKey,
         program::{
             BlockValidityWindow, ExecutionValidationError, PdaSeed, ProgramId,
             TimestampValidityWindow, WrappedBalanceSum,
@@ -478,7 +478,8 @@ pub mod tests {
 
     pub struct TestPrivateKeys {
         pub nsk: NullifierSecretKey,
-        pub vsk: Scalar,
+        pub d: [u8; 32],
+        pub r: [u8; 32],
     }
 
     impl TestPrivateKeys {
@@ -487,7 +488,7 @@ pub mod tests {
         }
 
         pub fn vpk(&self) -> ViewingPublicKey {
-            ViewingPublicKey::from_scalar(self.vsk)
+            ViewingPublicKey::from_seed(&self.d, &self.r)
         }
     }
 
@@ -1265,14 +1266,16 @@ pub mod tests {
     pub fn test_private_account_keys_1() -> TestPrivateKeys {
         TestPrivateKeys {
             nsk: [13; 32],
-            vsk: [31; 32],
+            d: [31; 32],
+            r: [32; 32],
         }
     }
 
     pub fn test_private_account_keys_2() -> TestPrivateKeys {
         TestPrivateKeys {
             nsk: [38; 32],
-            vsk: [83; 32],
+            d: [83; 32],
+            r: [84; 32],
         }
     }
 
@@ -1293,9 +1296,8 @@ pub mod tests {
         let recipient =
             AccountWithMetadata::new(Account::default(), false, (&recipient_keys.npk(), 0));
 
-        let esk = [3; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &recipient_keys.vpk());
-        let epk = EphemeralPublicKey::from_scalar(esk);
+        let (shared_secret, epk) =
+            SharedSecretKey::encapsulate_deterministic(&recipient_keys.vpk(), &[0u8; 32], 0);
 
         let (output, proof) = circuit::execute_and_prove(
             vec![sender, recipient],
@@ -1342,13 +1344,11 @@ pub mod tests {
         let recipient_pre =
             AccountWithMetadata::new(Account::default(), false, (&recipient_keys.npk(), 0));
 
-        let esk_1 = [3; 32];
-        let shared_secret_1 = SharedSecretKey::new(&esk_1, &sender_keys.vpk());
-        let epk_1 = EphemeralPublicKey::from_scalar(esk_1);
+        let (shared_secret_1, epk_1) =
+            SharedSecretKey::encapsulate_deterministic(&sender_keys.vpk(), &[0u8; 32], 0);
 
-        let esk_2 = [3; 32];
-        let shared_secret_2 = SharedSecretKey::new(&esk_2, &recipient_keys.vpk());
-        let epk_2 = EphemeralPublicKey::from_scalar(esk_2);
+        let (shared_secret_2, epk_2) =
+            SharedSecretKey::encapsulate_deterministic(&recipient_keys.vpk(), &[0u8; 32], 1);
 
         let (output, proof) = circuit::execute_and_prove(
             vec![sender_pre, recipient_pre],
@@ -1409,9 +1409,8 @@ pub mod tests {
             *recipient_account_id,
         );
 
-        let esk = [3; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &sender_keys.vpk());
-        let epk = EphemeralPublicKey::from_scalar(esk);
+        let (shared_secret, epk) =
+            SharedSecretKey::encapsulate_deterministic(&sender_keys.vpk(), &[0u8; 32], 0);
 
         let (output, proof) = circuit::execute_and_prove(
             vec![sender_pre, recipient_pre],
@@ -1916,14 +1915,24 @@ pub mod tests {
             Program::serialize_instruction(10_u128).unwrap(),
             vec![
                 InputAccountIdentity::PrivateAuthorizedUpdate {
-                    ssk: SharedSecretKey::new(&[55; 32], &sender_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &sender_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     nsk: recipient_keys.nsk,
                     membership_proof: (0, vec![]),
                     identifier: 0,
                 },
                 InputAccountIdentity::PrivateUnauthorized {
                     npk: recipient_keys.npk(),
-                    ssk: SharedSecretKey::new(&[56; 32], &recipient_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &recipient_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     identifier: 0,
                 },
             ],
@@ -1962,14 +1971,24 @@ pub mod tests {
             Program::serialize_instruction(10_u128).unwrap(),
             vec![
                 InputAccountIdentity::PrivateAuthorizedUpdate {
-                    ssk: SharedSecretKey::new(&[55; 32], &sender_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &sender_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     nsk: sender_keys.nsk,
                     membership_proof: (0, vec![]),
                     identifier: 0,
                 },
                 InputAccountIdentity::PrivateUnauthorized {
                     npk: recipient_keys.npk(),
-                    ssk: SharedSecretKey::new(&[56; 32], &recipient_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &recipient_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     identifier: 0,
                 },
             ],
@@ -2008,14 +2027,24 @@ pub mod tests {
             Program::serialize_instruction(10_u128).unwrap(),
             vec![
                 InputAccountIdentity::PrivateAuthorizedUpdate {
-                    ssk: SharedSecretKey::new(&[55; 32], &sender_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &sender_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     nsk: sender_keys.nsk,
                     membership_proof: (0, vec![]),
                     identifier: 0,
                 },
                 InputAccountIdentity::PrivateUnauthorized {
                     npk: recipient_keys.npk(),
-                    ssk: SharedSecretKey::new(&[56; 32], &recipient_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &recipient_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     identifier: 0,
                 },
             ],
@@ -2054,14 +2083,24 @@ pub mod tests {
             Program::serialize_instruction(10_u128).unwrap(),
             vec![
                 InputAccountIdentity::PrivateAuthorizedUpdate {
-                    ssk: SharedSecretKey::new(&[55; 32], &sender_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &sender_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     nsk: sender_keys.nsk,
                     membership_proof: (0, vec![]),
                     identifier: 0,
                 },
                 InputAccountIdentity::PrivateUnauthorized {
                     npk: recipient_keys.npk(),
-                    ssk: SharedSecretKey::new(&[56; 32], &recipient_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &recipient_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     identifier: 0,
                 },
             ],
@@ -2100,14 +2139,24 @@ pub mod tests {
             Program::serialize_instruction(10_u128).unwrap(),
             vec![
                 InputAccountIdentity::PrivateAuthorizedUpdate {
-                    ssk: SharedSecretKey::new(&[55; 32], &sender_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &sender_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     nsk: sender_keys.nsk,
                     membership_proof: (0, vec![]),
                     identifier: 0,
                 },
                 InputAccountIdentity::PrivateUnauthorized {
                     npk: recipient_keys.npk(),
-                    ssk: SharedSecretKey::new(&[56; 32], &recipient_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &recipient_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     identifier: 0,
                 },
             ],
@@ -2144,14 +2193,24 @@ pub mod tests {
             Program::serialize_instruction(10_u128).unwrap(),
             vec![
                 InputAccountIdentity::PrivateAuthorizedUpdate {
-                    ssk: SharedSecretKey::new(&[55; 32], &sender_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &sender_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     nsk: sender_keys.nsk,
                     membership_proof: (0, vec![]),
                     identifier: 0,
                 },
                 InputAccountIdentity::PrivateUnauthorized {
                     npk: recipient_keys.npk(),
-                    ssk: SharedSecretKey::new(&[56; 32], &recipient_keys.vpk()),
+                    ssk: SharedSecretKey::encapsulate_deterministic(
+                        &recipient_keys.vpk(),
+                        &[0u8; 32],
+                        0,
+                    )
+                    .0,
                     identifier: 0,
                 },
             ],
@@ -2170,7 +2229,8 @@ pub mod tests {
         let program = Program::simple_balance_transfer();
         let keys = test_private_account_keys_1();
         let npk = keys.npk();
-        let shared_secret = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
         let public_account_1 = AccountWithMetadata::new(
             Account {
                 program_owner: program.id(),
@@ -2211,7 +2271,8 @@ pub mod tests {
         let keys = test_private_account_keys_1();
         let npk = keys.npk();
         let seed = PdaSeed::new([42; 32]);
-        let shared_secret = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         let account_id = AccountId::for_private_pda(&program.id(), &seed, &npk, u128::MAX);
         let pre_state = AccountWithMetadata::new(Account::default(), false, account_id);
@@ -2247,7 +2308,8 @@ pub mod tests {
         let npk_a = keys_a.npk();
         let npk_b = keys_b.npk();
         let seed = PdaSeed::new([42; 32]);
-        let shared_secret = SharedSecretKey::new(&[55; 32], &keys_b.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&keys_b.vpk(), &[0u8; 32], 0).0;
 
         // `account_id` is derived from `npk_a`, but `npk_b` is supplied for this pre_state.
         // `AccountId::for_private_pda(program, seed, npk_b) != account_id`, so the claim check in
@@ -2281,7 +2343,8 @@ pub mod tests {
         let keys = test_private_account_keys_1();
         let npk = keys.npk();
         let seed = PdaSeed::new([77; 32]);
-        let shared_secret = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         let account_id = AccountId::for_private_pda(&delegator.id(), &seed, &npk, u128::MAX);
         let pre_state = AccountWithMetadata::new(Account::default(), false, account_id);
@@ -2319,7 +2382,8 @@ pub mod tests {
         let npk = keys.npk();
         let claim_seed = PdaSeed::new([77; 32]);
         let wrong_delegated_seed = PdaSeed::new([88; 32]);
-        let shared_secret = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
 
         let account_id = AccountId::for_private_pda(&delegator.id(), &claim_seed, &npk, u128::MAX);
         let pre_state = AccountWithMetadata::new(Account::default(), false, account_id);
@@ -2356,8 +2420,8 @@ pub mod tests {
         let keys_a = test_private_account_keys_1();
         let keys_b = test_private_account_keys_2();
         let seed = PdaSeed::new([55; 32]);
-        let shared_a = SharedSecretKey::new(&[66; 32], &keys_a.vpk());
-        let shared_b = SharedSecretKey::new(&[77; 32], &keys_b.vpk());
+        let shared_a = SharedSecretKey::encapsulate_deterministic(&keys_a.vpk(), &[0u8; 32], 0).0;
+        let shared_b = SharedSecretKey::encapsulate_deterministic(&keys_b.vpk(), &[0u8; 32], 0).0;
 
         let account_a = AccountId::for_private_pda(&program.id(), &seed, &keys_a.npk(), u128::MAX);
         let account_b = AccountId::for_private_pda(&program.id(), &seed, &keys_b.npk(), u128::MAX);
@@ -2402,7 +2466,8 @@ pub mod tests {
         let program = Program::noop();
         let keys = test_private_account_keys_1();
         let npk = keys.npk();
-        let shared_secret = SharedSecretKey::new(&[55; 32], &keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&keys.vpk(), &[0u8; 32], 0).0;
         let seed = PdaSeed::new([99; 32]);
 
         // Simulate a previously-claimed private PDA: program_owner != DEFAULT, is_authorized =
@@ -2501,7 +2566,8 @@ pub mod tests {
             (&sender_keys.npk(), 0),
         );
 
-        let shared_secret = SharedSecretKey::new(&[55; 32], &sender_keys.vpk());
+        let shared_secret =
+            SharedSecretKey::encapsulate_deterministic(&sender_keys.vpk(), &[0u8; 32], 0).0;
         let result = execute_and_prove(
             vec![private_account_1.clone(), private_account_1],
             Program::serialize_instruction(100_u128).unwrap(),
@@ -2841,9 +2907,8 @@ pub mod tests {
             AccountId::from(&PublicKey::new_from_private_key(&recipient_private_key));
         let recipient_pre =
             AccountWithMetadata::new(Account::default(), true, recipient_account_id);
-        let esk = [5; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &sender_keys.vpk());
-        let epk = EphemeralPublicKey::from_scalar(esk);
+        let (shared_secret, epk) =
+            SharedSecretKey::encapsulate_deterministic(&sender_keys.vpk(), &[0u8; 32], 0);
 
         let (output, proof) = execute_and_prove(
             vec![sender_pre, recipient_pre],
@@ -2942,13 +3007,11 @@ pub mod tests {
             None,
         );
 
-        let from_esk = [3; 32];
-        let from_ss = SharedSecretKey::new(&from_esk, &from_keys.vpk());
-        let from_epk = EphemeralPublicKey::from_scalar(from_esk);
+        let (from_ss, from_epk) =
+            SharedSecretKey::encapsulate_deterministic(&from_keys.vpk(), &[0u8; 32], 0);
 
-        let to_esk = [3; 32];
-        let to_ss = SharedSecretKey::new(&to_esk, &to_keys.vpk());
-        let to_epk = EphemeralPublicKey::from_scalar(to_esk);
+        let (to_ss, to_epk) =
+            SharedSecretKey::encapsulate_deterministic(&to_keys.vpk(), &[0u8; 32], 1);
 
         let mut dependencies = HashMap::new();
 
@@ -3245,9 +3308,8 @@ pub mod tests {
         let program = Program::authenticated_transfer_program();
 
         // Set up parameters for the new account
-        let esk = [3; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &private_keys.vpk());
-        let epk = EphemeralPublicKey::from_scalar(esk);
+        let (shared_secret, epk) =
+            SharedSecretKey::encapsulate_deterministic(&private_keys.vpk(), &[0u8; 32], 0);
 
         // Balance to initialize the account with (0 for a new account)
         let balance: u128 = 0;
@@ -3298,9 +3360,8 @@ pub mod tests {
             AccountWithMetadata::new(Account::default(), false, (&private_keys.npk(), 0));
 
         let program = Program::claimer();
-        let esk = [5; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &private_keys.vpk());
-        let epk = EphemeralPublicKey::from_scalar(esk);
+        let (shared_secret, epk) =
+            SharedSecretKey::encapsulate_deterministic(&private_keys.vpk(), &[0u8; 32], 0);
 
         let (output, proof) = execute_and_prove(
             vec![unauthorized_account],
@@ -3348,9 +3409,8 @@ pub mod tests {
         let claimer_program = Program::claimer();
 
         // Set up parameters for claiming the new account
-        let esk = [3; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &private_keys.vpk());
-        let epk = EphemeralPublicKey::from_scalar(esk);
+        let (shared_secret, epk) =
+            SharedSecretKey::encapsulate_deterministic(&private_keys.vpk(), &[0u8; 32], 0);
 
         let balance: u128 = 0;
 
@@ -3398,8 +3458,8 @@ pub mod tests {
         };
 
         let noop_program = Program::noop();
-        let esk2 = [4; 32];
-        let shared_secret2 = SharedSecretKey::new(&esk2, &private_keys.vpk());
+        let shared_secret2 =
+            SharedSecretKey::encapsulate_deterministic(&private_keys.vpk(), &[0u8; 32], 0).0;
 
         // Step 3: Try to execute noop program with authentication but without initialization
         let res = execute_and_prove(
@@ -3483,7 +3543,8 @@ pub mod tests {
             vec![private_account],
             Program::serialize_instruction(instruction).unwrap(),
             vec![InputAccountIdentity::PrivateAuthorizedUpdate {
-                ssk: SharedSecretKey::new(&[3; 32], &sender_keys.vpk()),
+                ssk: SharedSecretKey::encapsulate_deterministic(&sender_keys.vpk(), &[0u8; 32], 0)
+                    .0,
                 nsk: sender_keys.nsk,
                 membership_proof: (0, vec![]),
                 identifier: 0,
@@ -3509,7 +3570,8 @@ pub mod tests {
             vec![private_account],
             Program::serialize_instruction(instruction).unwrap(),
             vec![InputAccountIdentity::PrivateAuthorizedUpdate {
-                ssk: SharedSecretKey::new(&[3; 32], &sender_keys.vpk()),
+                ssk: SharedSecretKey::encapsulate_deterministic(&sender_keys.vpk(), &[0u8; 32], 0)
+                    .0,
                 nsk: sender_keys.nsk,
                 membership_proof: (0, vec![]),
                 identifier: 0,
@@ -3555,8 +3617,8 @@ pub mod tests {
         let balance_to_transfer = 10_u128;
         let instruction = (balance_to_transfer, auth_transfers.id());
 
-        let recipient_esk = [3; 32];
-        let recipient = SharedSecretKey::new(&recipient_esk, &recipient_keys.vpk());
+        let recipient =
+            SharedSecretKey::encapsulate_deterministic(&recipient_keys.vpk(), &[0u8; 32], 0).0;
 
         let mut dependencies = HashMap::new();
         dependencies.insert(auth_transfers.id(), auth_transfers);
@@ -3712,9 +3774,8 @@ pub mod tests {
         let pre = AccountWithMetadata::new(Account::default(), false, (&account_keys.npk(), 0));
         let mut state = V03State::new_with_genesis_accounts(&[], vec![], 0).with_test_programs();
         let tx = {
-            let esk = [3; 32];
-            let shared_secret = SharedSecretKey::new(&esk, &account_keys.vpk());
-            let epk = EphemeralPublicKey::from_scalar(esk);
+            let (shared_secret, epk) =
+                SharedSecretKey::encapsulate_deterministic(&account_keys.vpk(), &[0u8; 32], 0);
 
             let instruction = (
                 block_validity_window,
@@ -3782,9 +3843,8 @@ pub mod tests {
         let pre = AccountWithMetadata::new(Account::default(), false, (&account_keys.npk(), 0));
         let mut state = V03State::new_with_genesis_accounts(&[], vec![], 0).with_test_programs();
         let tx = {
-            let esk = [3; 32];
-            let shared_secret = SharedSecretKey::new(&esk, &account_keys.vpk());
-            let epk = EphemeralPublicKey::from_scalar(esk);
+            let (shared_secret, epk) =
+                SharedSecretKey::encapsulate_deterministic(&account_keys.vpk(), &[0u8; 32], 0);
 
             let instruction = (
                 BlockValidityWindow::new_unbounded(),
@@ -4338,8 +4398,10 @@ pub mod tests {
             ..Account::default()
         };
 
-        let alice_shared_0 = SharedSecretKey::new(&[10; 32], &alice_keys.vpk());
-        let alice_shared_1 = SharedSecretKey::new(&[11; 32], &alice_keys.vpk());
+        let (alice_shared_0, alice_epk_0) =
+            SharedSecretKey::encapsulate_deterministic(&alice_keys.vpk(), &[0u8; 32], 0);
+        let (alice_shared_1, alice_epk_1) =
+            SharedSecretKey::encapsulate_deterministic(&alice_keys.vpk(), &[0u8; 32], 1);
 
         // Fund alice_pda_0
         {
@@ -4365,11 +4427,7 @@ pub mod tests {
             let message = Message::try_from_circuit_output(
                 vec![funder_id],
                 vec![funder_nonce],
-                vec![(
-                    alice_npk,
-                    alice_keys.vpk(),
-                    EphemeralPublicKey::from_scalar([10; 32]),
-                )],
+                vec![(alice_npk, alice_keys.vpk(), alice_epk_0.clone())],
                 output,
             )
             .unwrap();
@@ -4407,11 +4465,7 @@ pub mod tests {
             let message = Message::try_from_circuit_output(
                 vec![funder_id],
                 vec![funder_nonce],
-                vec![(
-                    alice_npk,
-                    alice_keys.vpk(),
-                    EphemeralPublicKey::from_scalar([11; 32]),
-                )],
+                vec![(alice_npk, alice_keys.vpk(), alice_epk_1.clone())],
                 output,
             )
             .unwrap();
@@ -4457,11 +4511,7 @@ pub mod tests {
             let message = Message::try_from_circuit_output(
                 vec![recipient_id],
                 vec![Nonce(0)],
-                vec![(
-                    alice_npk,
-                    alice_keys.vpk(),
-                    EphemeralPublicKey::from_scalar([10; 32]),
-                )],
+                vec![(alice_npk, alice_keys.vpk(), alice_epk_0.clone())],
                 output,
             )
             .unwrap();
@@ -4501,11 +4551,7 @@ pub mod tests {
             let message = Message::try_from_circuit_output(
                 vec![recipient_id],
                 vec![],
-                vec![(
-                    alice_npk,
-                    alice_keys.vpk(),
-                    EphemeralPublicKey::from_scalar([11; 32]),
-                )],
+                vec![(alice_npk, alice_keys.vpk(), alice_epk_1.clone())],
                 output,
             )
             .unwrap();
diff --git a/sequencer/core/src/lib.rs b/sequencer/core/src/lib.rs
index df9aa87c..2a9ee5bf 100644
--- a/sequencer/core/src/lib.rs
+++ b/sequencer/core/src/lib.rs
@@ -1043,14 +1043,13 @@ mod tests {
         use nssa_core::{
             InputAccountIdentity, SharedSecretKey,
             account::AccountWithMetadata,
-            encryption::{EphemeralPublicKey, EphemeralSecretKey, ViewingPublicKey},
+            encryption::{EphemeralPublicKey, ViewingPublicKey},
         };
         use testnet_initial_state::PrivateAccountPublicInitialData;
 
         let nsk: nssa_core::NullifierSecretKey = [7; 32];
         let npk = nssa_core::NullifierPublicKey::from(&nsk);
-        let vsk: EphemeralSecretKey = [8; 32];
-        let vpk = ViewingPublicKey::from_scalar(vsk);
+        let vpk = ViewingPublicKey::from_seed(&[8u8; 32], &[9u8; 32]);
 
         let genesis_account = Account {
             program_owner: Program::authenticated_transfer_program().id(),
@@ -1068,9 +1067,7 @@ mod tests {
             SequencerCoreWithMockClients::start_from_config(config).await;
 
         // Attempt to re-initialize the same genesis account via a privacy-preserving transaction
-        let esk = [9; 32];
-        let shared_secret = SharedSecretKey::new(&esk, &vpk);
-        let epk = EphemeralPublicKey::from_scalar(esk);
+        let (shared_secret, epk) = SharedSecretKey::encapsulate_deterministic(&vpk, &[0u8; 32], 0);
 
         let (output, proof) = execute_and_prove(
             vec![AccountWithMetadata::new(
diff --git a/testnet_initial_state/src/lib.rs b/testnet_initial_state/src/lib.rs
index b5c91d4d..7902f6d2 100644
--- a/testnet_initial_state/src/lib.rs
+++ b/testnet_initial_state/src/lib.rs
@@ -4,7 +4,8 @@ use key_protocol::key_management::{
     secret_holders::{PrivateKeyHolder, SecretSpendingKey},
 };
 use nssa::{Account, AccountId, Data, PrivateKey, PublicKey, V03State};
-use nssa_core::{NullifierPublicKey, encryption::shared_key_derivation::Secp256k1Point};
+use nssa_core::{NullifierPublicKey, encryption::ViewingPublicKey};
+use key_protocol::key_management::secret_holders::ViewingSecretKey;
 use serde::{Deserialize, Serialize};
 
 const PRIVATE_KEY_PUB_ACC_A: [u8; 32] = [
@@ -47,15 +48,7 @@ const VSK_PRIV_ACC_B: [u8; 32] = [
     154, 161, 34, 208, 74, 27, 1, 119, 13, 88, 128,
 ];
 
-const VPK_PRIV_ACC_A: [u8; 33] = [
-    2, 210, 206, 38, 213, 4, 182, 198, 220, 47, 93, 148, 61, 84, 148, 250, 158, 45, 8, 81, 48, 80,
-    46, 230, 87, 210, 47, 204, 76, 58, 214, 167, 81,
-];
 
-const VPK_PRIV_ACC_B: [u8; 33] = [
-    2, 79, 110, 46, 203, 29, 206, 205, 18, 86, 27, 189, 104, 103, 113, 181, 110, 53, 78, 172, 11,
-    171, 190, 18, 126, 214, 81, 77, 192, 154, 58, 195, 238,
-];
 
 const NPK_PRIV_ACC_A: [u8; 32] = [
     167, 108, 50, 153, 74, 47, 151, 188, 140, 79, 195, 31, 181, 9, 40, 167, 201, 32, 175, 129, 45,
@@ -134,20 +127,20 @@ pub fn initial_priv_accounts_private_keys() -> Vec<PrivateAccountPrivateInitialD
         secret_spending_key: SecretSpendingKey(SSK_PRIV_ACC_A),
         private_key_holder: PrivateKeyHolder {
             nullifier_secret_key: NSK_PRIV_ACC_A,
-            viewing_secret_key: VSK_PRIV_ACC_A,
+            viewing_secret_key: ViewingSecretKey { d: VSK_PRIV_ACC_A, r: [0u8; 32] },
         },
         nullifier_public_key: NullifierPublicKey(NPK_PRIV_ACC_A),
-        viewing_public_key: Secp256k1Point(VPK_PRIV_ACC_A.to_vec()),
+        viewing_public_key: ViewingPublicKey::from_seed(&VSK_PRIV_ACC_A, &[0u8; 32]),
     };
 
     let key_chain_2 = KeyChain {
         secret_spending_key: SecretSpendingKey(SSK_PRIV_ACC_B),
         private_key_holder: PrivateKeyHolder {
             nullifier_secret_key: NSK_PRIV_ACC_B,
-            viewing_secret_key: VSK_PRIV_ACC_B,
+            viewing_secret_key: ViewingSecretKey { d: VSK_PRIV_ACC_B, r: [0u8; 32] },
         },
         nullifier_public_key: NullifierPublicKey(NPK_PRIV_ACC_B),
-        viewing_public_key: Secp256k1Point(VPK_PRIV_ACC_B.to_vec()),
+        viewing_public_key: ViewingPublicKey::from_seed(&VSK_PRIV_ACC_B, &[0u8; 32]),
     };
 
     vec![
diff --git a/wallet-ffi/src/types.rs b/wallet-ffi/src/types.rs
index 87c30315..46755715 100644
--- a/wallet-ffi/src/types.rs
+++ b/wallet-ffi/src/types.rs
@@ -4,7 +4,6 @@ use core::slice;
 use std::{ffi::c_char, ptr};
 
 use nssa::Data;
-use nssa_core::encryption::shared_key_derivation::Secp256k1Point;
 
 use crate::error::WalletFfiError;
 
@@ -161,11 +160,11 @@ impl FfiPrivateAccountKeys {
     }
 
     pub fn vpk(&self) -> Result<nssa_core::encryption::ViewingPublicKey, WalletFfiError> {
-        if self.viewing_public_key_len == 33 {
+        if self.viewing_public_key_len == 1184 {
             let slice = unsafe {
                 slice::from_raw_parts(self.viewing_public_key, self.viewing_public_key_len)
             };
-            Ok(Secp256k1Point(slice.to_vec()))
+            Ok(nssa_core::encryption::ViewingPublicKey(slice.to_vec()))
         } else {
             Err(WalletFfiError::InvalidKeyValue)
         }
diff --git a/wallet/src/cli/group.rs b/wallet/src/cli/group.rs
index e1dd9159..66ee056f 100644
--- a/wallet/src/cli/group.rs
+++ b/wallet/src/cli/group.rs
@@ -1,6 +1,6 @@
 use anyhow::{Context as _, Result};
 use clap::Subcommand;
-use key_protocol::key_management::group_key_holder::{GroupKeyHolder, SealingPublicKey};
+use key_protocol::key_management::{group_key_holder::{GroupKeyHolder, SealingPublicKey}, secret_holders::ViewingSecretKey};
 
 use crate::{
     WalletCore,
@@ -120,7 +120,7 @@ impl WalletSubcommand for GroupSubcommand {
                 }
 
                 let sealing_key =
-                    wallet_core.storage().user_data.sealing_secret_key.context(
+                    wallet_core.storage().user_data.sealing_secret_key.clone().context(
                         "No sealing key found. Run 'wallet group new-sealing-key' first.",
                     )?;
 
@@ -141,9 +141,13 @@ impl WalletSubcommand for GroupSubcommand {
                     anyhow::bail!("Sealing key already exists. Each wallet has one sealing key.");
                 }
 
-                let mut secret: nssa_core::encryption::Scalar = [0_u8; 32];
-                rand::RngCore::fill_bytes(&mut rand::rngs::OsRng, &mut secret);
-                let public_key = SealingPublicKey::from_scalar(secret);
+                let mut d = [0_u8; 32];
+                let mut r = [0_u8; 32];
+                rand::RngCore::fill_bytes(&mut rand::rngs::OsRng, &mut d);
+                rand::RngCore::fill_bytes(&mut rand::rngs::OsRng, &mut r);
+                let secret = ViewingSecretKey { d, r };
+                let ek_bytes = nssa_core::encryption::ViewingPublicKey::from_seed(&d, &r).0;
+                let public_key = SealingPublicKey::from_bytes(ek_bytes);
 
                 wallet_core.set_sealing_secret_key(secret);
                 wallet_core.store_persistent_data().await?;
diff --git a/wallet/src/cli/programs/native_token_transfer.rs b/wallet/src/cli/programs/native_token_transfer.rs
index f02ff99c..a1816422 100644
--- a/wallet/src/cli/programs/native_token_transfer.rs
+++ b/wallet/src/cli/programs/native_token_transfer.rs
@@ -405,10 +405,7 @@ impl WalletSubcommand for NativeTokenTransferProgramSubcommandPrivate {
                 let to_npk = nssa_core::NullifierPublicKey(to_npk);
 
                 let to_vpk_res = hex::decode(to_vpk)?;
-                let mut to_vpk = [0_u8; 33];
-                to_vpk.copy_from_slice(&to_vpk_res);
-                let to_vpk =
-                    nssa_core::encryption::shared_key_derivation::Secp256k1Point(to_vpk.to_vec());
+                let to_vpk = nssa_core::encryption::ViewingPublicKey(to_vpk_res);
 
                 let (tx_hash, [secret_from, _]) = NativeTokenTransfer(wallet_core)
                     .send_private_transfer_to_outer_account(
@@ -487,10 +484,7 @@ impl WalletSubcommand for NativeTokenTransferProgramSubcommandShielded {
                 let to_npk = nssa_core::NullifierPublicKey(to_npk);
 
                 let to_vpk_res = hex::decode(to_vpk)?;
-                let mut to_vpk = [0_u8; 33];
-                to_vpk.copy_from_slice(&to_vpk_res);
-                let to_vpk =
-                    nssa_core::encryption::shared_key_derivation::Secp256k1Point(to_vpk.to_vec());
+                let to_vpk = nssa_core::encryption::ViewingPublicKey(to_vpk_res);
 
                 let (tx_hash, _) = NativeTokenTransfer(wallet_core)
                     .send_shielded_transfer_to_outer_account(
diff --git a/wallet/src/cli/programs/token.rs b/wallet/src/cli/programs/token.rs
index 73bb6c2c..e2e390ae 100644
--- a/wallet/src/cli/programs/token.rs
+++ b/wallet/src/cli/programs/token.rs
@@ -898,11 +898,7 @@ impl WalletSubcommand for TokenProgramSubcommandPrivate {
                 let recipient_npk = nssa_core::NullifierPublicKey(recipient_npk);
 
                 let recipient_vpk_res = hex::decode(recipient_vpk)?;
-                let mut recipient_vpk = [0_u8; 33];
-                recipient_vpk.copy_from_slice(&recipient_vpk_res);
-                let recipient_vpk = nssa_core::encryption::shared_key_derivation::Secp256k1Point(
-                    recipient_vpk.to_vec(),
-                );
+                let recipient_vpk = nssa_core::encryption::ViewingPublicKey(recipient_vpk_res);
 
                 let (tx_hash, [secret_sender, _]) = Token(wallet_core)
                     .send_transfer_transaction_private_foreign_account(
@@ -1018,11 +1014,7 @@ impl WalletSubcommand for TokenProgramSubcommandPrivate {
                 let holder_npk = nssa_core::NullifierPublicKey(holder_npk);
 
                 let holder_vpk_res = hex::decode(holder_vpk)?;
-                let mut holder_vpk = [0_u8; 33];
-                holder_vpk.copy_from_slice(&holder_vpk_res);
-                let holder_vpk = nssa_core::encryption::shared_key_derivation::Secp256k1Point(
-                    holder_vpk.to_vec(),
-                );
+                let holder_vpk = nssa_core::encryption::ViewingPublicKey(holder_vpk_res);
 
                 let (tx_hash, [secret_definition, _]) = Token(wallet_core)
                     .send_mint_transaction_private_foreign_account(
@@ -1184,11 +1176,7 @@ impl WalletSubcommand for TokenProgramSubcommandShielded {
                 let recipient_npk = nssa_core::NullifierPublicKey(recipient_npk);
 
                 let recipient_vpk_res = hex::decode(recipient_vpk)?;
-                let mut recipient_vpk = [0_u8; 33];
-                recipient_vpk.copy_from_slice(&recipient_vpk_res);
-                let recipient_vpk = nssa_core::encryption::shared_key_derivation::Secp256k1Point(
-                    recipient_vpk.to_vec(),
-                );
+                let recipient_vpk = nssa_core::encryption::ViewingPublicKey(recipient_vpk_res);
 
                 let (tx_hash, _) = Token(wallet_core)
                     .send_transfer_transaction_shielded_foreign_account(
@@ -1326,11 +1314,7 @@ impl WalletSubcommand for TokenProgramSubcommandShielded {
                 let holder_npk = nssa_core::NullifierPublicKey(holder_npk);
 
                 let holder_vpk_res = hex::decode(holder_vpk)?;
-                let mut holder_vpk = [0_u8; 33];
-                holder_vpk.copy_from_slice(&holder_vpk_res);
-                let holder_vpk = nssa_core::encryption::shared_key_derivation::Secp256k1Point(
-                    holder_vpk.to_vec(),
-                );
+                let holder_vpk = nssa_core::encryption::ViewingPublicKey(holder_vpk_res);
 
                 let (tx_hash, _) = Token(wallet_core)
                     .send_mint_transaction_shielded_foreign_account(
diff --git a/wallet/src/config.rs b/wallet/src/config.rs
index e5d43024..7e92e566 100644
--- a/wallet/src/config.rs
+++ b/wallet/src/config.rs
@@ -112,7 +112,7 @@ pub struct PersistentStorage {
     >,
     /// Dedicated sealing secret key for GMS distribution.
     #[serde(default)]
-    pub sealing_secret_key: Option<nssa_core::encryption::Scalar>,
+    pub sealing_secret_key: Option<key_protocol::key_management::secret_holders::ViewingSecretKey>,
 }
 
 impl PersistentStorage {
diff --git a/wallet/src/helperfunctions.rs b/wallet/src/helperfunctions.rs
index 6b7cfa00..89a103e1 100644
--- a/wallet/src/helperfunctions.rs
+++ b/wallet/src/helperfunctions.rs
@@ -206,7 +206,7 @@ pub fn produce_data_for_storage(
         labels,
         group_key_holders: user_data.group_key_holders.clone(),
         shared_private_accounts: user_data.shared_private_accounts.clone(),
-        sealing_secret_key: user_data.sealing_secret_key,
+        sealing_secret_key: user_data.sealing_secret_key.clone(),
     }
 }
 
diff --git a/wallet/src/lib.rs b/wallet/src/lib.rs
index 24ac19b9..ec5547b3 100644
--- a/wallet/src/lib.rs
+++ b/wallet/src/lib.rs
@@ -317,7 +317,7 @@ impl WalletCore {
     }
 
     /// Set the wallet's dedicated sealing secret key.
-    pub const fn set_sealing_secret_key(&mut self, key: nssa_core::encryption::Scalar) {
+    pub fn set_sealing_secret_key(&mut self, key: key_protocol::key_management::secret_holders::ViewingSecretKey) {
         self.storage.user_data.sealing_secret_key = Some(key);
     }
 
@@ -791,7 +791,7 @@ impl WalletCore {
                     continue;
                 }
 
-                let shared_secret = SharedSecretKey::new(&vsk, &encrypted_data.epk);
+                let shared_secret = SharedSecretKey::decapsulate(&encrypted_data.epk, &vsk.d, &vsk.r);
                 let commitment = &tx.message.new_commitments[ciph_id];
 
                 if let Some((_kind, new_acc)) = nssa_core::EncryptionScheme::decrypt(
diff --git a/wallet/src/privacy_preserving_tx.rs b/wallet/src/privacy_preserving_tx.rs
index 603fdd0c..fbc282f7 100644
--- a/wallet/src/privacy_preserving_tx.rs
+++ b/wallet/src/privacy_preserving_tx.rs
@@ -121,9 +121,9 @@ impl AccountManager {
                 } => {
                     let acc = nssa_core::account::Account::default();
                     let auth_acc = AccountWithMetadata::new(acc, false, (&npk, identifier));
-                    let eph_holder = EphemeralKeyHolder::new(&npk);
-                    let ssk = eph_holder.calculate_shared_secret_sender(&vpk);
-                    let epk = eph_holder.generate_ephemeral_public_key();
+                    let eph_holder = EphemeralKeyHolder::new(&vpk);
+                    let ssk = eph_holder.calculate_shared_secret_sender();
+                    let epk = eph_holder.ephemeral_public_key().clone();
                     let pre = AccountPreparedData {
                         nsk: None,
                         npk,
@@ -150,9 +150,9 @@ impl AccountManager {
                 } => {
                     let acc = nssa_core::account::Account::default();
                     let auth_acc = AccountWithMetadata::new(acc, false, account_id);
-                    let eph_holder = EphemeralKeyHolder::new(&npk);
-                    let ssk = eph_holder.calculate_shared_secret_sender(&vpk);
-                    let epk = eph_holder.generate_ephemeral_public_key();
+                    let eph_holder = EphemeralKeyHolder::new(&vpk);
+                    let ssk = eph_holder.calculate_shared_secret_sender();
+                    let epk = eph_holder.ephemeral_public_key().clone();
                     let pre = AccountPreparedData {
                         nsk: None,
                         npk,
@@ -348,9 +348,9 @@ async fn private_key_tree_acc_preparation(
     // support from that in the wallet.
     let sender_pre = AccountWithMetadata::new(from_acc.clone(), true, account_id);
 
-    let eph_holder = EphemeralKeyHolder::new(&from_npk);
-    let ssk = eph_holder.calculate_shared_secret_sender(&from_vpk);
-    let epk = eph_holder.generate_ephemeral_public_key();
+    let eph_holder = EphemeralKeyHolder::new(&from_vpk);
+    let ssk = eph_holder.calculate_shared_secret_sender();
+    let epk = eph_holder.ephemeral_public_key().clone();
 
     Ok(AccountPreparedData {
         nsk: Some(nsk),
@@ -393,9 +393,9 @@ async fn private_shared_acc_preparation(
         None
     };
 
-    let eph_holder = EphemeralKeyHolder::new(&npk);
-    let ssk = eph_holder.calculate_shared_secret_sender(&vpk);
-    let epk = eph_holder.generate_ephemeral_public_key();
+    let eph_holder = EphemeralKeyHolder::new(&vpk);
+    let ssk = eph_holder.calculate_shared_secret_sender();
+    let epk = eph_holder.ephemeral_public_key().clone();
 
     Ok(AccountPreparedData {
         nsk: exists.then_some(nsk),
@@ -419,7 +419,7 @@ mod tests {
         let acc = PrivacyPreservingAccount::PrivateShared {
             nsk: [0; 32],
             npk: NullifierPublicKey([1; 32]),
-            vpk: ViewingPublicKey::from_scalar([2; 32]),
+            vpk: ViewingPublicKey::from_seed(&[2u8; 32], &[3u8; 32]),
             identifier: 42,
         };
         assert!(acc.is_private());