make auditor pubkey optional in mint and burn proof generation

Author: samkim-crypto

token/confidential-transfer/proof-generation/src/burn.rs

@@ -36,9 +36,12 @@ pub fn burn_split_proof_data(
     burn_amount: u64,
     source_elgamal_keypair: &ElGamalKeypair,
     source_aes_key: &AeKey,
-    auditor_elgamal_pubkey: &ElGamalPubkey,
+    auditor_elgamal_pubkey: Option<&ElGamalPubkey>,
     supply_elgamal_pubkey: &ElGamalPubkey,
 ) -> Result<BurnProofData, TokenProofGenerationError> {
+    let default_auditor_pubkey = ElGamalPubkey::default();
+    let auditor_elgamal_pubkey = auditor_elgamal_pubkey.unwrap_or(&default_auditor_pubkey);
+
     // split the burn amount into low and high bits
     let (burn_amount_lo, burn_amount_hi) = try_split_u64(burn_amount, BURN_AMOUNT_LO_BIT_LENGTH)
         .ok_or(TokenProofGenerationError::IllegalAmountBitLength)?;

token/confidential-transfer/proof-generation/src/mint.rs

@@ -38,8 +38,11 @@ pub fn mint_split_proof_data(
     supply_elgamal_keypair: &ElGamalKeypair,
     supply_aes_key: &AeKey,
     destination_elgamal_pubkey: &ElGamalPubkey,
-    auditor_elgamal_pubkey: &ElGamalPubkey,
+    auditor_elgamal_pubkey: Option<&ElGamalPubkey>,
 ) -> Result<MintProofData, TokenProofGenerationError> {
+    let default_auditor_pubkey = ElGamalPubkey::default();
+    let auditor_elgamal_pubkey = auditor_elgamal_pubkey.unwrap_or(&default_auditor_pubkey);
+
     // split the mint amount into low and high bits
     let (mint_amount_lo, mint_amount_hi) = try_split_u64(mint_amount, MINT_AMOUNT_LO_BIT_LENGTH)
         .ok_or(TokenProofGenerationError::IllegalAmountBitLength)?;

token/confidential-transfer/proof-tests/tests/proof_test.rs

@@ -238,7 +238,7 @@ fn test_mint_validity(mint_amount: u64, supply: u64) {
         &supply_keypair,
         &supply_aes_key,
         destination_pubkey,
-        auditor_pubkey,
+        Some(auditor_pubkey),
     )
     .unwrap();
 
@@ -291,7 +291,7 @@ fn test_burn_validity(spendable_balance: u64, burn_amount: u64) {
         burn_amount,
         &source_keypair,
         &aes_key,
-        auditor_pubkey,
+        Some(auditor_pubkey),
         supply_pubkey,
     )
     .unwrap();