Make JoinSplit descriptions generic over the proof system.

zebra-chain/src/transaction.rs

@@ -10,10 +10,11 @@ mod transparent;
 mod tests;
 
 pub use hash::TransactionHash;
-pub use joinsplit::{JoinSplitBctv14, JoinSplitGroth16, LegacyJoinSplitData, SaplingJoinSplitData};
+pub use joinsplit::{JoinSplit, JoinSplitData, SproutInputNoteData, SproutOutputNoteData};
 pub use shielded_data::{OutputDescription, ShieldedData, SpendDescription};
 pub use transparent::{OutPoint, TransparentInput, TransparentOutput};
 
+use crate::proofs::{Bctv14Proof, Groth16Proof};
 use crate::types::{BlockHeight, LockTime};
 
 /// A Zcash transaction.
@@ -49,7 +50,7 @@ pub enum Transaction {
         /// chain.
         lock_time: LockTime,
         /// The JoinSplit data for this transaction, if any.
-        joinsplit_data: Option<LegacyJoinSplitData>,
+        joinsplit_data: Option<JoinSplitData<Bctv14Proof>>,
     },
     /// An Overwinter transaction (`version = 3`).
     V3 {
@@ -63,7 +64,7 @@ pub enum Transaction {
         /// The latest block height that this transaction can be added to the chain.
         expiry_height: BlockHeight,
         /// The JoinSplit data for this transaction, if any.
-        joinsplit_data: Option<LegacyJoinSplitData>,
+        joinsplit_data: Option<JoinSplitData<Bctv14Proof>>,
     },
     /// A Sapling transaction (`version = 4`).
     V4 {
@@ -82,6 +83,6 @@ pub enum Transaction {
         /// The shielded data for this transaction, if any.
         shielded_data: Option<ShieldedData>,
         /// The JoinSplit data for this transaction, if any.
-        joinsplit_data: Option<SaplingJoinSplitData>,
+        joinsplit_data: Option<JoinSplitData<Groth16Proof>>,
     },
 }

zebra-chain/src/transaction/joinsplit.rs

@@ -1,3 +1,5 @@
+use crate::proofs::ZkSnarkProof;
+
 /// Describes input notes to a Sprout transaction.
 ///
 /// The [protocol specification §7.2][ps] describes these fields as being encoded
@@ -41,12 +43,11 @@ pub struct SproutOutputNoteData {
     pub enc_ciphertext: Vec<u8>,
 }
 
-/// A _JoinSplit Description_ using BCTV14 proofs, as described in [protocol
-/// specification §7.2][ps].
+/// A _JoinSplit Description_, as described in [protocol specification §7.2][ps].
 ///
 /// [ps]: https://zips.z.cash/protocol/protocol.pdf#joinsplitencoding
 #[derive(Clone, Debug, PartialEq, Eq)]
-pub struct JoinSplitBctv14 {
+pub struct JoinSplit<P: ZkSnarkProof> {
     /// A value that the JoinSplit transfer removes from the transparent value
     /// pool.
     ///
@@ -57,64 +58,32 @@ pub struct JoinSplitBctv14 {
     ///
     /// XXX refine to an Amount
     vpub_new: u64,
-
     /// A root of the Sprout note commitment tree at some block height in the
     /// past, or the root produced by a previous JoinSplit transfer in this
     /// transaction.
     ///
     /// XXX refine type
     anchor: [u8; 32],
-
     /// An X25519 public key.
     ///
     /// XXX refine to an x25519-dalek type?
     ephemeral_key: [u8; 32],
-
     /// A 256-bit seed that must be chosen independently at random for each
     /// JoinSplit description.
     random_seed: [u8; 32],
-
     /// A sequence of input notes for this transaction.
     input_notes: Vec<SproutInputNoteData>,
-
     /// A sequence of output notes for this transaction.
     output_notes: Vec<SproutOutputNoteData>,
-
-    /// A ZK JoinSplit proof using BCTV14.
-    ///
-    /// XXX refine type
-    /// XXX this should be a [u8; 296] but trait impls.
-    zkproof: Vec<u8>,
-}
-
-/// A _JoinSplit Description_ using Groth16 proofs, as described in [protocol
-/// specification §7.2][ps].
-///
-/// [ps]: https://zips.z.cash/protocol/protocol.pdf#joinsplitencoding
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct JoinSplitGroth16 {
-    // XXX use generic's
+    /// A ZK JoinSplit proof, either a [`Groth16Proof`] or a [`Bctv14Proof`].
+    zkproof: P,
 }
 
-/// Pre-Sapling JoinSplit data using Sprout-on-BCTV14 proofs.
+/// A bundle of JoinSplit descriptions and signature data.
 #[derive(Clone, Debug, PartialEq, Eq)]
-pub struct LegacyJoinSplitData {
+pub struct JoinSplitData<P: ZkSnarkProof> {
     /// A sequence of JoinSplit descriptions using BCTV14 proofs.
-    pub joinsplits: Vec<JoinSplitBctv14>,
-    /// The public key for the JoinSplit signature.
-    // XXX refine to a Zcash-flavored Ed25519 pubkey.
-    pub pub_key: [u8; 32],
-    /// The JoinSplit signature.
-    // XXX refine to a Zcash-flavored Ed25519 signature.
-    // for now it's [u64; 8] rather than [u8; 64] to get trait impls
-    pub sig: [u64; 8],
-}
-
-/// Post-Sapling JoinSplit data using Sprout-on-Groth16 proofs.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct SaplingJoinSplitData {
-    /// A sequence of JoinSplit descriptions using Groth16 proofs.
-    pub joinsplits: Vec<JoinSplitGroth16>,
+    pub joinsplits: Vec<JoinSplit<P>>,
     /// The public key for the JoinSplit signature.
     // XXX refine to a Zcash-flavored Ed25519 pubkey.
     pub pub_key: [u8; 32],