Solana is planning to phase out durable nonces, a feature that allows transactions to be signed offline and broadcast later. The proposed replacement involves adding a program between the cold key’s approval and execution, changing which addresses control affected assets. This shift impacts exchanges, custodians, and treasury operators using offline signing methods, requiring them to migrate assets, adjust applications, and update risk policies.
The Foundation’s October deprecation plan introduces onchain signer programs to verify offline signatures and execute approved instructions. A program-derived address (PDA) will control the affected accounts, while the original key retains authorization. The migration period is conditional on a suitable replacement being ready, audited, and live on mainnet. The Foundation has not yet chosen between Anza’s Programmatic Signer and Blueshift’s Vector.
Durable nonces address a timing issue by allowing offline signers to approve transactions using a stored nonce, decoupling approval from broadcast. The recent 200ms slot upgrade on Solana’s mainnet reduces the approval window, making offline signing methods more critical. The proposed replacement architectures differ in how they handle native SOL and transaction constraints, with Programmatic Signer allowing more flexibility in assembling execution contexts and Vector requiring pre-approved instruction sequences.
Operators must ensure their applications accept actions arriving through the new signer program. Token-2022’s CPI Guard highlights potential compatibility issues, as some applications may reject nested instructions. Institutional concerns have been raised about application access and custody controls, with some participants favoring alternative solutions like transaction envelopes or Sudo.