Integrate DR into PrivateV1 (#32)

* Add crate

* Initialize session

* Add encrypt / decrypt

Cargo.lock

@@ -506,6 +506,7 @@ dependencies = [
  "blake2",
  "chat-proto",
  "crypto",
+ "double-ratchets",
  "hex",
  "prost",
  "rand_core",

conversations/Cargo.toml

@@ -10,6 +10,7 @@ crate-type = ["staticlib","dylib"]
 blake2.workspace = true
 chat-proto = { git = "https://github.com/logos-messaging/chat_proto" }
 crypto = { path = "../crypto" }
+double-ratchets = { path = "../double-ratchets" }
 hex = "0.4.3"
 prost = "0.14.1"
 rand_core = { version = "0.6" }

conversations/src/conversation/privatev1.rs

@@ -3,35 +3,92 @@ use chat_proto::logoschat::{
     encryption::{Doubleratchet, EncryptedPayload, encrypted_payload::Encryption},
 };
 use crypto::SecretKey;
+use double_ratchets::{Header, InstallationKeyPair, RatchetState};
 use prost::{Message, bytes::Bytes};
+use std::fmt::Debug;
+use x25519_dalek::PublicKey;
 
 use crate::{
     conversation::{ChatError, ConversationId, Convo, Id},
+    errors::EncryptionError,
+    proto,
     types::AddressedEncryptedPayload,
     utils::timestamp_millis,
 };
 
-#[derive(Debug)]
-pub struct PrivateV1Convo {}
+pub struct PrivateV1Convo {
+    dr_state: RatchetState,
+}
 
 impl PrivateV1Convo {
-    pub fn new(_seed_key: SecretKey) -> Self {
-        Self {}
+    pub fn new_initiator(seed_key: SecretKey, remote: PublicKey) -> Self {
+        // TODO: Danger - Fix double-ratchets types to Accept SecretKey
+        // perhaps update the  DH to work with cryptocrate.
+        // init_sender doesn't take ownership of the key so a reference can be used.
+        let shared_secret: [u8; 32] = seed_key.as_bytes().to_vec().try_into().unwrap();
+        Self {
+            dr_state: RatchetState::init_sender(shared_secret, remote),
+        }
     }
 
-    fn encrypt(&self, frame: PrivateV1Frame) -> EncryptedPayload {
-        // TODO: Integrate DR
+    pub fn new_responder(seed_key: SecretKey, dh_self: InstallationKeyPair) -> Self {
+        Self {
+            // TODO: Danger - Fix double-ratchets types to Accept SecretKey
+            dr_state: RatchetState::init_receiver(seed_key.as_bytes().to_owned(), dh_self),
+        }
+    }
+
+    fn encrypt(&mut self, frame: PrivateV1Frame) -> EncryptedPayload {
+        let encoded_bytes = frame.encode_to_vec();
+        let (cipher_text, header) = self.dr_state.encrypt_message(&encoded_bytes);
 
         EncryptedPayload {
             encryption: Some(Encryption::Doubleratchet(Doubleratchet {
-                dh: Bytes::from(vec![]),
-                msg_num: 0,
-                prev_chain_len: 1,
-                ciphertext: Bytes::from(frame.encode_to_vec()),
+                dh: Bytes::from(Vec::from(header.dh_pub.to_bytes())),
+                msg_num: header.msg_num,
+                prev_chain_len: header.prev_chain_len,
+                ciphertext: Bytes::from(cipher_text),
                 aux: "".into(),
             })),
         }
     }
+
+    fn decrypt(&mut self, payload: EncryptedPayload) -> Result<PrivateV1Frame, EncryptionError> {
+        // Validate and extract the encryption header or return errors
+        let dr_header = if let Some(enc) = payload.encryption {
+            if let proto::Encryption::Doubleratchet(dr) = enc {
+                dr
+            } else {
+                return Err(EncryptionError::Decryption(
+                    "incorrect encryption type".into(),
+                ));
+            }
+        } else {
+            return Err(EncryptionError::Decryption("missing payload".into()));
+        };
+
+        // Turn the bytes into a PublicKey
+        let byte_arr: [u8; 32] = dr_header
+            .dh
+            .to_vec()
+            .try_into()
+            .map_err(|_| EncryptionError::Decryption("invalid public key length".into()))?;
+        let dh_pub = PublicKey::from(byte_arr);
+
+        // Build the Header that DR impl expects
+        let header = Header {
+            dh_pub,
+            msg_num: dr_header.msg_num,
+            prev_chain_len: dr_header.prev_chain_len,
+        };
+
+        // Decrypt into Frame
+        let content_bytes = self
+            .dr_state
+            .decrypt_message(&dr_header.ciphertext, header)
+            .map_err(|e| EncryptionError::Decryption(e.to_string()))?;
+        Ok(PrivateV1Frame::decode(content_bytes.as_slice()).unwrap())
+    }
 }
 
 impl Id for PrivateV1Convo {
@@ -66,3 +123,53 @@ impl Convo for PrivateV1Convo {
         self.id().into()
     }
 }
+
+impl Debug for PrivateV1Convo {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("PrivateV1Convo")
+            .field("dr_state", &"******")
+            .finish()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use x25519_dalek::StaticSecret;
+
+    use super::*;
+
+    #[test]
+    fn test_encrypt_roundtrip() {
+        let saro = StaticSecret::random();
+        let raya = StaticSecret::random();
+
+        let pub_raya = PublicKey::from(&raya);
+
+        let seed_key = saro.diffie_hellman(&pub_raya);
+        let send_content_bytes = vec![0, 2, 4, 6, 8];
+        let mut sr_convo =
+            PrivateV1Convo::new_initiator(SecretKey::from(seed_key.to_bytes()), pub_raya);
+
+        let installation_key_pair = InstallationKeyPair::from(raya);
+        let mut rs_convo = PrivateV1Convo::new_responder(
+            SecretKey::from(seed_key.to_bytes()),
+            installation_key_pair,
+        );
+
+        let send_frame = PrivateV1Frame {
+            conversation_id: "_".into(),
+            sender: Bytes::new(),
+            timestamp: timestamp_millis(),
+            frame_type: Some(FrameType::Content(Bytes::from(send_content_bytes.clone()))),
+        };
+        let payload = sr_convo.encrypt(send_frame.clone());
+        let recv_frame = rs_convo.decrypt(payload).unwrap();
+
+        assert!(
+            recv_frame == send_frame,
+            "{:?}. {:?}",
+            recv_frame,
+            send_content_bytes
+        );
+    }
+}

conversations/src/errors.rs

@@ -21,3 +21,11 @@ pub enum ChatError {
     #[error("convo with handle: {0} was not found")]
     NoConvo(u32),
 }
+
+#[derive(Error, Debug)]
+pub enum EncryptionError {
+    #[error("encryption: {0}")]
+    Encryption(String),
+    #[error("decryption: {0}")]
+    Decryption(String),
+}

conversations/src/inbox/handshake.rs

@@ -63,7 +63,7 @@ impl InboxHandshake {
     /// Derive keys from X3DH shared secret
     fn derive_keys_from_shared_secret(shared_secret: SecretKey) -> SecretKey {
         let seed_key: [u8; 32] = Blake2bMac256::new_with_salt_and_personal(
-            shared_secret.as_bytes(),
+            shared_secret.as_slice(),
             &[], // No salt - input already has high entropy
             b"InboxV1-Seed",
         )

conversations/src/inbox/inbox.rs

@@ -1,3 +1,4 @@
+use double_ratchets::InstallationKeyPair;
 use hex;
 use prost::Message;
 use prost::bytes::Bytes;
@@ -88,7 +89,7 @@ impl Inbox {
         let (seed_key, ephemeral_pub) =
             InboxHandshake::perform_as_initiator(&self.ident.secret(), &pkb, &mut rng);
 
-        let mut convo = PrivateV1Convo::new(seed_key);
+        let mut convo = PrivateV1Convo::new_initiator(seed_key, remote_bundle.ephemeral_key);
 
         let mut payloads = convo.send_message(initial_message.as_bytes())?;
 
@@ -139,16 +140,11 @@ impl Inbox {
 
     fn perform_handshake(
         &self,
-        payload: proto::EncryptedPayload,
+        ephemeral_key: &StaticSecret,
+        header: proto::InboxHeaderV1,
+        bytes: Bytes,
     ) -> Result<(SecretKey, proto::InboxV1Frame), ChatError> {
-        let handshake = Self::extract_payload(payload)?;
-        let header = handshake
-            .header
-            .ok_or(ChatError::UnexpectedPayload("InboxV1Header".into()))?;
-        let pubkey_hex = hex::encode(header.responder_ephemeral.as_ref());
-
-        let ephemeral_key = self.lookup_ephemeral_key(&pubkey_hex)?;
-
+        // Get PublicKeys from protobuf
         let initator_static = PublicKey::from(
             <[u8; 32]>::try_from(header.initiator_static.as_ref())
                 .map_err(|_| ChatError::BadBundleValue("wrong size - initator static".into()))?,
@@ -168,7 +164,7 @@ impl Inbox {
         );
 
         // TODO: Decrypt Content
-        let frame = proto::InboxV1Frame::decode(handshake.payload)?;
+        let frame = proto::InboxV1Frame::decode(bytes)?;
         Ok((seed_key, frame))
     }
 
@@ -215,14 +211,23 @@ impl ConvoFactory for Inbox {
             return Err(ChatError::Protocol("Example error".into()));
         }
 
-        let ep = proto::EncryptedPayload::decode(message)?;
-        let (seed_key, frame) = self.perform_handshake(ep)?;
+        let handshake = Self::extract_payload(proto::EncryptedPayload::decode(message)?)?;
+
+        let header = handshake
+            .header
+            .ok_or(ChatError::UnexpectedPayload("InboxV1Header".into()))?;
+
+        // Get Ephemeral key used by the initator
+        let key_index = hex::encode(header.responder_ephemeral.as_ref());
+        let ephemeral_key = self.lookup_ephemeral_key(&key_index)?;
+
+        // Perform handshake and decrypt frame
+        let (seed_key, frame) = self.perform_handshake(ephemeral_key, header, handshake.payload)?;
 
         match frame.frame_type.unwrap() {
-            chat_proto::logoschat::inbox::inbox_v1_frame::FrameType::InvitePrivateV1(
-                _invite_private_v1,
-            ) => {
-                let convo = PrivateV1Convo::new(seed_key);
+            proto::inbox_v1_frame::FrameType::InvitePrivateV1(_invite_private_v1) => {
+                let convo = PrivateV1Convo::new_responder(seed_key, ephemeral_key.clone().into());
+
                 // TODO: Update PrivateV1 Constructor with DR, initial_message
                 Ok((Box::new(convo), vec![]))
             }

conversations/src/proto.rs

@@ -2,7 +2,7 @@ pub use chat_proto::logoschat::encryption::encrypted_payload::Encryption;
 pub use chat_proto::logoschat::encryption::inbox_handshake_v1::InboxHeaderV1;
 pub use chat_proto::logoschat::encryption::{EncryptedPayload, InboxHandshakeV1};
 pub use chat_proto::logoschat::envelope::EnvelopeV1;
-pub use chat_proto::logoschat::inbox::InboxV1Frame;
+pub use chat_proto::logoschat::inbox::{InboxV1Frame, inbox_v1_frame};
 pub use chat_proto::logoschat::invite::InvitePrivateV1;
 
 pub use prost::Message;

crypto/src/keys.rs

@@ -7,9 +7,13 @@ use zeroize::{Zeroize, ZeroizeOnDrop};
 pub struct SecretKey([u8; 32]);
 
 impl SecretKey {
-    pub fn as_bytes(&self) -> &[u8] {
+    pub fn as_slice(&self) -> &[u8] {
         self.0.as_slice()
     }
+
+    pub fn as_bytes(&self) -> &[u8; 32] {
+        &self.0
+    }
 }
 
 impl From<[u8; 32]> for SecretKey {

double-ratchets/src/keypair.rs

@@ -37,3 +37,13 @@ impl InstallationKeyPair {
         Self { secret, public }
     }
 }
+
+impl From<StaticSecret> for InstallationKeyPair {
+    fn from(value: StaticSecret) -> Self {
+        let public = PublicKey::from(&value);
+        Self {
+            secret: value,
+            public,
+        }
+    }
+}