[token-2022] Add doc regarding the ability of withdraw withheld authority [ZELLIC-3.4] (#3773)

* Mention the corresponding proof instruction in the token instruction doc

* add warning about withheld fees authority

Author: samkim-crypto

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

@@ -110,6 +110,9 @@ pub enum ConfidentialTransferInstruction {
     /// prior to account closing if no instructions beyond
     /// `ConfidentialTransferInstruction::ConfigureAccount` have affected the token account.
     ///
+    /// In order for this instruction to be successfully processed, it must be accompanied by the
+    /// `VerifyCloseAccount` instruction of the `zk_token_proof` program in the same transaction.
+    ///
     ///   * Single owner/delegate
     ///   0. `[writable]` The SPL Token account.
     ///   1. `[]` Instructions sysvar.
@@ -157,6 +160,9 @@ pub enum ConfidentialTransferInstruction {
     /// Fails if the source or destination accounts are frozen.
     /// Fails if the associated mint is extended as `NonTransferable`.
     ///
+    /// In order for this instruction to be successfully processed, it must be accompanied by the
+    /// `VerifyWithdraw` instruction of the `zk_token_proof` program in the same transaction.
+    ///
     /// Accounts expected by this instruction:
     ///
     ///   * Single owner/delegate
@@ -179,6 +185,10 @@ pub enum ConfidentialTransferInstruction {
 
     /// Transfer tokens confidentially.
     ///
+    /// In order for this instruction to be successfully processed, it must be accompanied by
+    /// either the `VerifyTransfer` or `VerifyTransferWithFee` instruction of the `zk_token_proof`
+    /// program in the same transaction.
+    ///
     /// Fails if the associated mint is extended as `NonTransferable`.
     ///
     ///   * Single owner/delegate
@@ -266,6 +276,10 @@ pub enum ConfidentialTransferInstruction {
     /// Transfer all withheld confidential tokens in the mint to an account. Signed by the mint's
     /// withdraw withheld tokens authority.
     ///
+    /// In order for this instruction to be successfully processed, it must be accompanied by the
+    /// `VerifyWithdrawWithheldTokens` instruction of the `zk_token_proof` program in the same
+    /// transaction.
+    ///
     /// Accounts expected by this instruction:
     ///
     ///   * Single owner/delegate
@@ -307,6 +321,10 @@ pub enum ConfidentialTransferInstruction {
     /// `HarvestWithheldTokensToMint` and then move the withheld fees from mint to a specified
     /// destination account using `WithdrawWithheldTokensFromMint`.
     ///
+    /// In order for this instruction to be successfully processed, it must be accompanied by the
+    /// `VerifyWithdrawWithheldTokens` instruction of the `zk_token_proof` program in the same
+    /// transaction.
+    ///
     /// Accounts expected by this instruction:
     ///
     ///   * Single owner/delegate

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

@@ -57,11 +57,20 @@ pub struct ConfidentialTransferMint {
     ///              `ConfidentialTransferInstruction::ConfigureAccount`)
     pub auto_approve_new_accounts: PodBool,
 
+    /// Authority to decode any transfer amount in a confidential transafer.
+    ///
     /// * 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_encryption_pubkey: EncryptionPubkey,
 
+    /// Authority to withraw withheld fees that are associated with accounts. It must be set to an
+    /// all zero pubkey if the mint is not extended for fees.
+    ///
+    /// Note that the withdraw withheld authority has the ability to decode any withheld fee
+    /// amount that are associated with accounts. When combined with the fee parameters, the
+    /// withheld fee amounts can reveal information about transfer amounts.
+    ///
     /// * 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.