--- title: Confidential Transfer description: Learn about the Confidential Transfer extension and how to use it to add optional features to token mints and accounts. --- ## What are Confidential Transfers? Confidential transfers enable you to transfer tokens between token accounts without revealing the transfer amount. This is useful for privacy-preserving transactions. Only the transfer amounts and token balances are private. The token account addresses remain public. - [Protocol Overview](https://www.solana-program.com/docs/confidential-balances/overview) - Details on the underlying cryptographic protocol - [Quick Start Guide](https://www.solana-program.com/docs/confidential-balances#setup) - Setup and basic CLI commands - [Confidential Balances Cookbook](https://github.com/solana-developers/Confidential-Balances-Sample) - Code snippets on how to use the Confidential Transfer extension ### How does it work? The Confidential Transfer extension adds [instructions](https://github.com/solana-program/token-2022/blob/efd0c957fefbd79882d77df5fb2dac88c001249c/program/src/extension/confidential_transfer/instruction.rs#L29) to the Token Extension program that allows you to transfer tokens between accounts without revealing the transfer amount. ```mermaid title="Confidential Transfer Basic Overview" sequenceDiagram participant A as Sender Wallet participant AA as Sender Token Account participant BB as Recipient Token Account participant B as Recipient Wallet A->>AA: Deposit A->>AA: Apply AA->>BB: Transfer B->>BB: Apply B->>BB: Withdraw ``` The basic flow of confidential token transfers is as follows: 1. Create a mint account with the confidential transfer extension. 2. Create token accounts with confidential transfer extension for the sender and recipient. 3. Mint tokens to the sender account. 4. **Deposit** sender's public balance to **confidential pending balance**. 5. **Apply** sender's pending balance to **confidential available balance**. 6. Confidentially **transfer** tokens from sender token account to recipient token account. 7. **Apply** recipient's pending balance to **confidential available balance**. 8. **Withdraw** recipient's confidential available balance to **public balance**. For more details on the steps in the confidential transfer flow, see the corresponding pages: How to create a mint account with the Confidential Transfer extension How to configure a token account with the Confidential Transfer extension How to deposit tokens to confidential pending balance How to apply pending balance to available confidential balance How to withdraw tokens from confidential available balance How to confidentially transfer tokens between token accounts How wallets, explorers, and exchanges can support confidential transfer tokens How to issue and operate a confidential transfer token (approve policy, auditors, fees, mint and burn) The diagram below shows a detailed sequence of the basic flow for confidential token transfers: ```mermaid title="Confidential Transfer Detailed Overview" sequenceDiagram participant Sender as Sender Wallet participant SenderAccount as Sender Token Account participant Mint as Token Mint participant Token22 as Token Extensions Program participant ATAProgram as Associated Token Program participant ElGamal as ZK ElGamal Proof Program participant RecipientAccount as Recipient Token Account participant Recipient as Recipient Wallet rect rgba(120, 160, 235, 0.3) Note over Sender,Mint: 1. Initialize Mint activate Sender Sender->>Token22: create_mint (with Confidential Transfer Extension) activate Token22 Token22-->>Mint: Initialize mint deactivate Token22 deactivate Sender end rect rgba(130, 210, 170, 0.3) Note over Sender,SenderAccount: 2. Set Up Sender Account activate Sender Note right of Sender: Generate encryption keys Sender->>Sender: Generate ElGamal keypair Sender->>Sender: Generate AES key Sender->>ATAProgram: create_associated_token_account activate ATAProgram ATAProgram->>Token22: Create token account at deterministic address activate Token22 Token22-->>SenderAccount: Initialize account deactivate Token22 deactivate ATAProgram Sender->>Token22: reallocate & configure_account activate Token22 Token22-->>SenderAccount: Configure for confidential transfers deactivate Token22 deactivate Sender end rect rgba(130, 210, 170, 0.3) Note over Recipient,RecipientAccount: 3. Set Up Recipient Account activate Recipient Note right of Recipient: Generate encryption keys Recipient->>Recipient: Generate ElGamal keypair Recipient->>Recipient: Generate AES key Recipient->>ATAProgram: create_associated_token_account activate ATAProgram ATAProgram->>Token22: Create token account at deterministic address activate Token22 Token22-->>RecipientAccount: Initialize account deactivate Token22 deactivate ATAProgram Recipient->>Token22: reallocate & configure_account activate Token22 Token22-->>RecipientAccount: Configure for confidential transfers deactivate Token22 deactivate Recipient end rect rgba(235, 160, 80, 0.3) Note over Sender,SenderAccount: 4. Mint & Convert to Confidential Balance activate Sender Sender->>Token22: mint_tokens activate Token22 Token22-->>SenderAccount: Increase token account public balance deactivate Token22 Sender->>Token22: deposit_tokens activate Token22 Token22-->>SenderAccount: Convert to confidential pending balance deactivate Token22 Sender->>Sender: Use ElGamal keypair & AES key to decrypt Sender->>Token22: apply_pending_balance activate Token22 Token22-->>SenderAccount: Convert pending balance to available balance deactivate Token22 deactivate Sender end rect rgba(235, 120, 120, 0.3) Note over Sender,RecipientAccount: 5. Confidential Transfer activate Sender Note right of Sender: Create proofs Sender->>Sender: Generate proof data for transfer Sender->>ElGamal: Create equality proof context account activate ElGamal Sender->>ElGamal: Create ciphertext validity proof context account Sender->>ElGamal: Create range proof context account ElGamal-->>ElGamal: Verify proofs Sender->>Token22: transfer_tokens, providing proof context accounts activate Token22 Token22-->>SenderAccount: Decrease encrypted available balance Token22-->>RecipientAccount: Increase encrypted pending balance deactivate Token22 Sender->>ElGamal: Close proof context accounts deactivate ElGamal deactivate Sender end rect rgba(180, 150, 235, 0.3) Note over Recipient,RecipientAccount: 6. Apply & Withdraw activate Recipient Recipient->>Recipient: Use ElGamal keypair & AES key to decrypt Recipient->>Token22: apply_pending_balance activate Token22 Token22-->>RecipientAccount: Convert pending balance to available balance deactivate Token22 Note right of Recipient: Optional withdrawal Recipient->>Recipient: Generate proof data for withdraw Recipient->>ElGamal: Create equality proof context account activate ElGamal Recipient->>ElGamal: Create range proof context account ElGamal-->>ElGamal: Verify proofs Recipient->>Token22: withdraw_tokens, providing proof context accounts activate Token22 Token22-->>RecipientAccount: Convert from available confidential balance to public balance deactivate Token22 Recipient->>ElGamal: Close proof context accounts deactivate ElGamal deactivate Recipient end ``` ## Confidential Transfer Instructions The full list of Confidential Transfer extension [instructions](https://github.com/solana-program/token-2022/blob/efd0c957fefbd79882d77df5fb2dac88c001249c/program/src/extension/confidential_transfer/instruction.rs#L29) are as follows: | Instruction | Description | | ----------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- | | _rs`InitializeMint`_ | Sets up mint account for confidential transfers. This instruction must be included in the same transaction as _rs`TokenInstruction::InitializeMint`_ instruction. | | _rs`UpdateMint`_ | Updates confidential transfer settings for a mint. | | _rs`ConfigureAccount`_ | Sets up a token account for confidential transfers. | | _rs`ApproveAccount`_ | Approves a token account for confidential transfers if the mint requires approval for new token accounts. | | _rs`EmptyAccount`_ | Empties the pending and available confidential balances to allow closing a token account. | | _rs`Deposit`_ | Converts public token balance into pending confidential balance. | | _rs`Withdraw`_ | Converts available confidential balance back to public balance. | | _rs`Transfer`_ | Transfers tokens between token accounts confidentially. | | _rs`ApplyPendingBalance`_ | Converts pending balance into available balance after deposits or transfers. | | _rs`EnableConfidentialCredits`_ | Allows a token account to receive confidential token transfers. | | _rs`DisableConfidentialCredits`_ | Blocks incoming confidential transfers while still allowing public transfers. | | _rs`EnableNonConfidentialCredits`_ | Allows a token account to receive public token transfers. | | _rs`DisableNonConfidentialCredits`_ | Blocks regular transfers to make account receive only confidential transfers. | | _rs`TransferWithFee`_ | Transfers tokens between token accounts confidentially with a fee. | | _rs`ConfigureAccountWithRegistry`_ | Alternative way to configure token accounts for confidential transfers using an _rs`ElGamalRegistry`_ account instead of _rs`VerifyPubkeyValidity`_ proof. |