SPL Token Wrap Program

This program enables the creation of "wrapped" versions of existing SPL tokens, facilitating interoperability between different token standards. If you are building an app with a mint/token and find yourself wishing you could take advantage of some of the latest features of a specific token program, this might be for you!

Features

• Bidirectional Wrapping: Convert tokens between SPL Token and SPL Token 2022 standards in either direction, including conversions between different SPL Token 2022 mints.
• Extensible Mint Creation: The CreateMint instruction is designed to be extensible through the MintCustomizer trait. By forking the program and implementing this trait, developers can add custom logic to:
  • Include any SPL Token 2022 extensions on the new wrapped mint.
  • Modify default properties like the freeze_authority and decimals.
• Confidential Transfers by Default: All wrapped tokens created under the Token-2022 standard automatically include the ConfidentialTransferMint extension, enabling the option for privacy-preserving transactions. This feature is immutable and requires no additional configuration.
• Transfer Hook Compatibility: Integrates with tokens that implement the SPL Transfer Hook interface, enabling custom logic on token transfers.
• Multisignature Support: Compatible with multisig signers for both wrapping and unwrapping operations.

How It Works

It supports four primary operations:

1. CreateMint: This operation initializes a new wrapped token mint and its associated backpointer account. Note, the caller must pre-fund this account with lamports. This is to avoid requiring writer+signer privileges on this instruction.

   • Wrapped Mint: An SPL Token or SPL Token 2022 mint account is created. The address of this mint is a PDA derived from the unwrapped token's mint address and the wrapped token program ID. This ensures a unique, deterministic relationship between the wrapped and unwrapped tokens. The wrapped mint's authority is also a PDA, controlled by the Token Wrap program.
   • Backpointer: An account (also a PDA, derived from the wrapped mint address) is created to store the address of the original unwrapped token mint. This allows anyone to easily determine the unwrapped token corresponding to a wrapped token, facilitating unwrapping.

2. Wrap: This operation accepts deposits of unwrapped tokens and mints wrapped tokens.

   • Unwrapped tokens are transferred from the user's account to an escrow account. Any unwrapped token account whose owner is a PDA controlled by the Token Wrap program can be used.
   • An equivalent amount of wrapped tokens is minted to the user's wrapped token account.

3. Unwrap: This operation burns wrapped tokens and releases unwrapped token deposits.

   • Wrapped tokens are burned from the user's wrapped token account.
   • An equivalent amount of unwrapped tokens is transferred from the escrow account to the user's unwrapped token account.

4. CloseStuckEscrow: This operation handles an edge case with re-creating a mint with the MintCloseAuthority extension.

   • The escrow ATA can get "stuck" when an unwrapped mint with a close authority is closed and then a new mint is created at the same address but with different extensions, leaving the escrow ATA (Associated Token Account) in an incompatible state.
   • The instruction closes the old escrow ATA and returns the lamports to a specified destination account.
   • This operation will only succeed if the current escrow has zero balance and has different extensions than the mint.
   • After closing the stuck escrow, the client is responsible for recreating the ATA with the correct extensions.

The 1:1 relationship between wrapped and unwrapped tokens is maintained through the escrow mechanism, ensuring that wrapped tokens are always fully backed by their unwrapped counterparts.

Permissionless design

The SPL Token Wrap program is designed to be permissionless. This means:

• Anyone can create a wrapped mint: No special permissions or whitelisting is required to create a wrapped version of an existing mint. The CreateMint instruction is open to all users, provided they can pay the required rent for the new accounts.
• Anyone can wrap and unwrap tokens: Once a wrapped mint has been created, any user holding the underlying unwrapped tokens can use the Wrap and Unwrap instructions. All transfers are controlled by PDAs owned by the Token Wrap program itself. However, it is important to note that if the unwrapped token has a freeze authority, that freeze authority is preserved in the wrapped token.

Confidential Transfer extension

The ConfidentialTransferMint extension is added to every Token-2022 wrapped mint and initialized with the following config:

• No Authority: The confidential transfer authority is set to None, making the configuration immutable. This ensures that the privacy features cannot be disabled or altered after the wrapped mint is created.
• No Auditor: The wrapped mints are created without a confidential transfer auditor. This means that there is no third party that can view the details of confidential transactions.
• Automatic Account Approval: New token accounts are approved for confidential transfers by default. This allows users to make private transactions permissionlessly.

Customizing mint

If the current wrapped mint config does not suit your needs, please fork! A few places you are going to want to update:

• Add a new struct that implements MintCustomizer in program/src/mint_customizer
• Replace the current one in use within the processor: program/src/processor.rs
• Re-run tests (see package.json) and update/remove assertions to accommodate new config
• If wanting to make use of clients:
  • CLI: Update mint customizer type in clients/cli/src/create_mint.rs
  • JS: Update mint size in clients/js/src/create-mint.ts

Audits

Auditor	Date	Version	Report
Zellic	2025-05-16	75c5529	PDF
Runtime Verification	2025-06-11	dd71fc1	PDF

Getting Started

Prerequisites

1. Install Solana CLI

   • Ensure version matches the crate manifest.

2. Install pnpm

3. Install project dependencies:

   pnpm install

Building and Testing

1. Build the Program:

   pnpm programs:build

2. Run Tests:

   pnpm programs:test

License

This project is licensed under the Apache License 2.0.