add death constraints to metadata

goas/atomic_asset_transfer/common/Cargo.toml

@@ -8,4 +8,5 @@ serde = { version = "1", features = ["derive"] }
 cl = { path = "../../cl/cl" }
 goas_proof_statements = { path = "../proof_statements" }
 proof_statements = { path = "../../cl/proof_statements" }
-once_cell = "1"
+once_cell = "1"
+sha2 = "0.10"

goas/atomic_asset_transfer/common/src/lib.rs

@@ -7,6 +7,7 @@ use cl::{
 };
 use once_cell::sync::Lazy;
 use serde::{Deserialize, Serialize};
+use sha2::{Digest, Sha256};
 use std::collections::BTreeMap;
 
 // TODO: sparse merkle tree
@@ -20,27 +21,44 @@ pub struct StateCommitment([u8; 32]);
 
 pub type AccountId = u32;
 
-// PLACEHOLDER: replace with the death constraint vk of the zone funds
-pub const ZONE_FUNDS_VK: [u8; 32] = [0; 32];
 // PLACEHOLDER: this is probably going to be NMO?
 pub static ZONE_CL_FUNDS_UNIT: Lazy<Unit> = Lazy::new(|| crypto::hash_to_curve(b"NMO"));
-// PLACEHOLDER
-pub static ZONE_UNIT: Lazy<Unit> = Lazy::new(|| crypto::hash_to_curve(b"ZONE_UNIT"));
-// PLACEHOLDER
-pub const ZONE_NF_PK: NullifierCommitment = NullifierCommitment::from_bytes([0; 32]);
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ZoneMetadata {
+    pub self_vk: [u8; 32],
+    pub funds_vk: [u8; 32],
+    pub unit: Unit,
+}
+
+impl ZoneMetadata {
+    pub fn id(&self) -> [u8; 32] {
+        let mut hasher = Sha256::new();
+        hasher.update(&self.self_vk);
+        hasher.update(&self.funds_vk);
+        hasher.update(self.unit.compress().as_bytes());
+        hasher.finalize().into()
+    }
+}
 
 #[derive(Clone, Serialize, Deserialize)]
 pub struct StateWitness {
     pub balances: BTreeMap<u32, u32>,
     pub included_txs: Vec<Input>,
     pub output_events: Vec<Event>,
+    pub zone_metadata: ZoneMetadata,
 }
 
 impl StateWitness {
     pub fn commit(&self) -> StateCommitment {
-        let root = self.balances_root();
-        let root = cl::merkle::node(self.events_root(), root);
-        let root = cl::merkle::node(self.included_txs_root(), root);
+        let io_root = cl::merkle::node(self.events_root(), self.included_txs_root());
+
+        let balances_root = self.balances_root();
+        let zone_id = self.zone_metadata.id();
+        let state_root = cl::merkle::node(zone_id, balances_root);
+
+        let root = cl::merkle::node(io_root, state_root);
+
         StateCommitment(root)
     }
 

goas/atomic_asset_transfer/risc0_proofs/zone_state/src/main.rs

@@ -54,6 +54,8 @@ fn deposit(
         zone_funds_out,
     } = deposit;
 
+    let funds_vk = state.zone_metadata.funds_vk;
+
     // 1) Check there are no more input/output notes than expected
     let inputs = [
         deposit.commit().to_bytes().to_vec(),
@@ -74,13 +76,13 @@ fn deposit(
     assert_eq!(ptx_root, pub_inputs.ptx_root);
 
     // 2) Check the deposit note is not already under control of the zone
-    assert_ne!(deposit.note.death_constraint, ZONE_FUNDS_VK);
+    assert_ne!(deposit.note.death_constraint, funds_vk);
 
     // 3) Check the ptx is balanced. This is not a requirement for standard ptxs, but we need it
     //    in deposits (at least in a first version) to ensure fund tracking
-    assert_eq!(deposit.note.unit, *ZONE_UNIT);
-    assert_eq!(zone_funds_in.note.unit, *ZONE_UNIT);
-    assert_eq!(zone_funds_out.note.unit, *ZONE_UNIT);
+    assert_eq!(deposit.note.unit, *ZONE_CL_FUNDS_UNIT);
+    assert_eq!(zone_funds_in.note.unit, *ZONE_CL_FUNDS_UNIT);
+    assert_eq!(zone_funds_out.note.unit, *ZONE_CL_FUNDS_UNIT);
 
     let in_sum = deposit.note.value + zone_funds_in.note.value;
 
@@ -89,8 +91,8 @@ fn deposit(
     assert_eq!(out_sum, in_sum, "deposit ptx is unbalanced");
 
     // 4) Check the zone fund notes are correctly created
-    assert_eq!(zone_funds_in.note.death_constraint, ZONE_FUNDS_VK);
-    assert_eq!(zone_funds_out.note.death_constraint, ZONE_FUNDS_VK);
+    assert_eq!(zone_funds_in.note.death_constraint, funds_vk);
+    assert_eq!(zone_funds_out.note.death_constraint, funds_vk);
     assert_eq!(zone_funds_in.nf_sk, NullifierSecret::from_bytes([0; 16])); // there is no secret in the zone funds
     assert_eq!(zone_funds_out.nf_pk, zone_funds_in.nf_sk.commit()); // the sk is the same
                                                                     // nonce is correctly evolved
@@ -136,6 +138,11 @@ fn validate_zone_input(
     let nf = Nullifier::new(input.input.nf_sk, input.input.nonce);
 
     assert_eq!(input.input.note.state, <[u8; 32]>::from(state.commit()));
+    // should not be possible to create one but let's put this check here just in case
+    debug_assert_eq!(
+        input.input.note.death_constraint,
+        state.zone_metadata.self_vk
+    );
 
     (ptx_root, nf)
 }
@@ -149,10 +156,10 @@ fn validate_zone_output(
     assert_eq!(ptx, output.ptx_root()); // the ptx root is the same as in the input
     let output = output.output;
     assert_eq!(output.note.state, <[u8; 32]>::from(state.commit())); // the state in the output is as calculated by this function
-    assert_eq!(output.note.death_constraint, input.note.death_constraint); // the death constraint is the same as the on in the input
+    assert_eq!(output.note.death_constraint, state.zone_metadata.self_vk); // the death constraint is the correct one
     assert_eq!(output.nf_pk, NullifierSecret::from_bytes([0; 16]).commit()); // the nullifier secret is public
     assert_eq!(output.balance_blinding, input.balance_blinding); // the balance blinding is the same as in the input
-    assert_eq!(output.note.unit, input.note.unit); // the balance unit is the same as in the input
+    assert_eq!(output.note.unit, state.zone_metadata.unit); // the balance unit is the same as in the input
 
     // the nonce is correctly evolved
     assert_eq!(