feat!: embed the transaction which spent the inputs within the Dbc st…

…ruct

examples/mint-repl/mint-repl.rs

@@ -683,6 +683,7 @@ fn write_to_spentbook(mintinfo: &mut MintInfo, mut dbc_builder: DbcBuilder) -> R
             dbc_builder =
                 dbc_builder.add_spent_proof_share(sb_node.log_spent(key_image, tx.clone())?);
         }
+        dbc_builder = dbc_builder.add_spent_transaction(tx);
     }
     Ok(dbc_builder)
 }

src/builder.rs

@@ -313,10 +313,8 @@ impl TransactionBuilder {
             ));
         }
 
-        // Grand finale!  sign the ringct_material to generate a Tx.
-        let result: Result<(RingCtTransaction, Vec<RevealedCommitment>)> =
-            ringct_material.sign(rng).map_err(|e| e.into());
-        let (transaction, revealed_commitments) = result?;
+        // Grand finale! sign the ringct_material to generate a Tx.
+        let (transaction, revealed_commitments) = ringct_material.sign(rng)?;
 
         Ok(DbcBuilder::new(
             transaction,
@@ -337,6 +335,7 @@ pub struct DbcBuilder {
     pub ringct_material: RingCtMaterial,
 
     pub spent_proof_shares: BTreeMap<KeyImage, HashSet<SpentProofShare>>,
+    pub spent_transactions: Vec<RingCtTransaction>,
 }
 
 impl DbcBuilder {
@@ -351,8 +350,9 @@ impl DbcBuilder {
             transaction,
             revealed_commitments,
             output_owner_map,
-            spent_proof_shares: Default::default(),
             ringct_material,
+            spent_proof_shares: Default::default(),
+            spent_transactions: Vec::default(),
         }
     }
 
@@ -387,6 +387,12 @@ impl DbcBuilder {
         self
     }
 
+    /// Add a transaction which spent one of the inputs
+    pub fn add_spent_transaction(mut self, spent_tx: RingCtTransaction) -> Self {
+        self.spent_transactions.push(spent_tx);
+        self
+    }
+
     /// Build the output DBCs, verifying the transaction and spentproofs.
     ///
     /// see TransactionVerifier::verify() for a description of
@@ -401,6 +407,15 @@ impl DbcBuilder {
         // note that we do this just once for entire Tx, not once per output Dbc.
         TransactionVerifier::verify(verifier, &self.transaction, &spent_proofs)?;
 
+        // verify there is a maching spent transaction for each spent_proof
+        if !spent_proofs.iter().all(|proof| {
+            self.spent_transactions
+                .iter()
+                .any(|tx| Hash::from(tx.hash()) == proof.transaction_hash())
+        }) {
+            return Err(Error::MissingSpentTransaction);
+        }
+
         // build output DBCs
         self.build_output_dbcs(spent_proofs)
     }
@@ -456,6 +471,7 @@ impl DbcBuilder {
                     )),
                     transaction: self.transaction.clone(),
                     spent_proofs: spent_proofs.clone(),
+                    spent_transactions: self.spent_transactions.clone(),
                 };
                 (dbc, owner_once.clone(), amount_secrets_list[0].clone())
             })

src/error.rs

@@ -35,6 +35,9 @@ pub enum Error {
     #[error("OutputProof not found in transaction outputs")]
     OutputProofNotFound,
 
+    #[error("Missing spent transaction for at least one of the spent proofs")]
+    MissingSpentTransaction,
+
     #[error("public key is not unique across all transaction outputs")]
     PublicKeyNotUniqueAcrossOutputs,
 

src/mint.rs

@@ -91,7 +91,9 @@ mod tests {
                 Ok(s) => s,
                 Err(e) => return check_error(e),
             };
-            dbc_builder = dbc_builder.add_spent_proof_share(spent_proof_share);
+            dbc_builder = dbc_builder
+                .add_spent_proof_share(spent_proof_share)
+                .add_spent_transaction(tx);
         }
         let output_dbcs = dbc_builder.build(&spentbook_node.key_manager)?;
 
@@ -200,7 +202,9 @@ mod tests {
                     Ok(s) => s,
                     Err(e) => return check_tx_error(e),
                 };
-            dbc_builder = dbc_builder.add_spent_proof_share(spent_proof_share);
+            dbc_builder = dbc_builder
+                .add_spent_proof_share(spent_proof_share)
+                .add_spent_transaction(tx);
         }
 
         let output_dbcs = dbc_builder.build(&spentbook_node.key_manager)?;
@@ -320,7 +324,9 @@ mod tests {
                 }
             };
 
-            dbc_builder = dbc_builder.add_spent_proof_share(spent_proof_share);
+            dbc_builder = dbc_builder
+                .add_spent_proof_share(spent_proof_share)
+                .add_spent_transaction(tx);
         }
 
         let many_to_many_result = dbc_builder.build(&spentbook_node.key_manager);
@@ -466,8 +472,9 @@ mod tests {
             .build(&mut rng)?;
 
         for (key_image, tx) in dbc_builder.inputs() {
-            dbc_builder =
-                dbc_builder.add_spent_proof_share(spentbook.log_spent(key_image, tx.clone())?);
+            dbc_builder = dbc_builder
+                .add_spent_proof_share(spentbook.log_spent(key_image, tx.clone())?)
+                .add_spent_transaction(tx);
         }
 
         // build output DBCs
@@ -564,8 +571,11 @@ mod tests {
         // normally spentbook verifies the tx, but here we skip it in order to obtain
         // a spentproof with an invalid tx.
         for (key_image, tx) in dbc_builder_fudged.inputs() {
-            let spent_proof_share = spentbook.log_spent_and_skip_tx_verification(key_image, tx)?;
-            dbc_builder_fudged = dbc_builder_fudged.add_spent_proof_share(spent_proof_share);
+            let spent_proof_share =
+                spentbook.log_spent_and_skip_tx_verification(key_image, tx.clone())?;
+            dbc_builder_fudged = dbc_builder_fudged
+                .add_spent_proof_share(spent_proof_share)
+                .add_spent_transaction(tx);
         }
 
         // The builder should give an error because the sum(inputs) does not equal sum(outputs)
@@ -643,8 +653,10 @@ mod tests {
         )?;
 
         for (key_image, tx) in dbc_builder_true.inputs() {
-            let spent_proof_share = new_spentbook.log_spent(key_image, tx)?;
-            dbc_builder_true = dbc_builder_true.add_spent_proof_share(spent_proof_share);
+            let spent_proof_share = new_spentbook.log_spent(key_image, tx.clone())?;
+            dbc_builder_true = dbc_builder_true
+                .add_spent_proof_share(spent_proof_share)
+                .add_spent_transaction(tx);
         }
 
         // Now that the SpentBook is correct, we have a valid spent_proof_share

src/mock/genesis_builder.rs

@@ -99,6 +99,7 @@ impl GenesisBuilder {
                 dbc_builder = dbc_builder
                     .add_spent_proof_share(spentbook_node.log_spent(key_image, tx.clone())?);
             }
+            dbc_builder = dbc_builder.add_spent_transaction(tx);
         }
 
         // note: for our (mock) purposes, all spentbook nodes are verified to

src/spent_proof.rs

@@ -118,7 +118,7 @@ impl SpentProofShare {
         &self.spentbook_pks
     }
 
-    /// represent this SpentProofContent as bytes
+    /// represent this SpentProofShare as bytes
     pub fn to_bytes(&self) -> Vec<u8> {
         let mut bytes = self.content.to_bytes();