token-2022: add fee for confidential extension (#2897)

* token-2022: add fee for confidential extension

* token-2022: change receiver to dest for consistency

* token-2022: addressing readability review comments for confidential extension

Author: samkim-crypto

Cargo.lock

@@ -19,7 +19,7 @@ num-derive = "0.3"
 num-traits = "0.2"
 num_enum = "0.5.4"
 solana-program = "1.9.5"
-solana-zk-token-sdk = "0.4.0"
+solana-zk-token-sdk = "0.6.0"
 thiserror = "1.0"
 
 [dev-dependencies]

token/program-2022/Cargo.toml

@@ -121,9 +121,16 @@ pub enum TokenError {
     /// Calculated fee does not match expected fee
     #[error("Calculated fee does not match expected fee")]
     FeeMismatch,
+    /// Fee parameters associated with confidential transfer zero-knowledge proofs do not match fee parameters in mint
+    #[error(
+        "Fee parameters associated with zero-knowledge proofs do not match fee parameters in mint"
+    )]
+    FeeParametersMismatch,
     /// The owner authority cannot be changed
     #[error("The owner authority cannot be changed")]
     ImmutableOwner,
+
+    // 35
     /// An account can only be closed if its withheld fee balance is zero, harvest fees to the
     /// mint and try again
     #[error("An account can only be closed if its withheld fee balance is zero, harvest fees to the mint and try again")]

token/program-2022/src/error.rs

@@ -232,7 +232,7 @@ pub enum ConfidentialTransferInstruction {
 #[repr(C)]
 pub struct ConfigureAccountInstructionData {
     /// The public key associated with the account
-    pub elgamal_pk: pod::ElGamalPubkey,
+    pub elgamal_pubkey: pod::ElGamalPubkey,
     /// The decryptable balance (always 0) once the configure account succeeds
     pub decryptable_zero_balance: pod::AeCiphertext,
 }
@@ -372,7 +372,7 @@ pub fn configure_account(
     token_program_id: &Pubkey,
     token_account: &Pubkey,
     mint: &Pubkey,
-    elgamal_pk: ElGamalPubkey,
+    elgamal_pubkey: ElGamalPubkey,
     decryptable_zero_balance: AeCiphertext,
     authority: &Pubkey,
     multisig_signers: &[&Pubkey],
@@ -393,7 +393,7 @@ pub fn configure_account(
         accounts,
         ConfidentialTransferInstruction::ConfigureAccount,
         &ConfigureAccountInstructionData {
-            elgamal_pk: elgamal_pk.into(),
+            elgamal_pubkey: elgamal_pubkey.into(),
             decryptable_zero_balance: decryptable_zero_balance.into(),
         },
     )])

token/program-2022/src/extension/confidential_transfer/instruction.rs

@@ -38,7 +38,14 @@ pub struct ConfidentialTransferMint {
     /// * If non-zero, transfers must include ElGamal cypertext with this public key permitting the
     /// auditor to decode the transfer amount.
     /// * If all zero, auditing is currently disabled.
-    pub auditor_pk: pod::ElGamalPubkey,
+    pub auditor_pubkey: pod::ElGamalPubkey,
+
+    /// * If non-zero, transfers must include ElGamal cypertext of the transfer fee with this
+    /// public key. If this is the case, but the base mint is not extended for fees, then any
+    /// transfer will fail.
+    /// * If all zero, transfer fee is disabled. If this is the case, but the base mint is extended
+    /// for fees, then any transfer will fail.
+    pub withdraw_withheld_authority_pubkey: pod::ElGamalPubkey,
 }
 
 impl Extension for ConfidentialTransferMint {
@@ -54,12 +61,12 @@ pub struct ConfidentialTransferAccount {
     pub approved: PodBool,
 
     /// The public key associated with ElGamal encryption
-    pub elgamal_pk: pod::ElGamalPubkey,
+    pub elgamal_pubkey: pod::ElGamalPubkey,
 
-    /// The pending balance (encrypted by `elgamal_pk`)
+    /// The pending balance (encrypted by `elgamal_pubkey`)
     pub pending_balance: pod::ElGamalCiphertext,
 
-    /// The available balance (encrypted by `elgamal_pk`)
+    /// The available balance (encrypted by `elgamal_pubkey`)
     pub available_balance: pod::ElGamalCiphertext,
 
     /// The decryptable available balance
@@ -77,6 +84,9 @@ pub struct ConfidentialTransferAccount {
 
     /// The actual `pending_balance_credit_counter` when the last `ApplyPendingBalance` instruction was executed
     pub actual_pending_balance_credit_counter: PodU64,
+
+    /// The withheld amount of fees. This will always be zero if fees are never enabled.
+    pub withheld_amount: pod::ElGamalCiphertext,
 }
 
 impl Extension for ConfidentialTransferAccount {