Solana plans to end the signature that never expires

A proposal filed on 5 November by Gabe Rodriguez of Anza, which builds Solana validator software, would change one rule on the network: “After activation, every transaction needs a recent blockhash”.SIMD-0723: Remove Durable Nonces (proposal text, 5 November 2026). It says the change “will not be activated on mainnet-beta before 2027-05-05”.

The rule would end durable nonces, the feature that lets a signed Solana transaction wait indefinitely before it is sent. It is the mechanism attackers used to drain Drift, a Solana trading protocol, in April.CoinDesk, Solana moves to scrap the transaction feature used in the $270 million Drift hack. Drift counts $295,706,374.93 in assets taken,Drift, Incident Recovery Update, 16 April 2026. and CoinDesk reported that Drift later blamed the attack on a North Korean state-affiliated group. The proposal does not rest its case on Drift. The people who would feel it most are the ones it names: “custodians and exchanges that use air-gapped signing, where approvals take longer than that window”.

A stamp that never goes stale

Every ordinary Solana transaction carries a recent blockhash, a reference to a recent block. The proposal states the rule plainly: “A transaction expires once its recent blockhash is more than 150 blocks old”. At the network’s current 200ms slots, the Solana Foundation puts that at about 30 seconds.Solana Foundation, Durable Nonce Deprecation (October 2026). A signature that is not used in that window is worthless.

Durable nonces were added in 2019 to support offline and delayed signing. In the Foundation’s words, “Durable nonces swap the blockhash for a stored value, so the transaction never expires”. The Foundation says they are used “when approval processes require air-gapped signing or long approval flows, common for exchanges, custodians, and stablecoin issuers”. An air-gapped machine is one kept off the internet. A key held on one can sign, but carrying that signature to the network and gathering the other approvals a large transfer needs can take far longer than 30 seconds.

Eight days on the ledger

Drift’s theft shows what a signature with no expiry does. The two transactions that took control of Drift’s administrative powers are public on the Solana ledger. Both begin with an instruction to advance a nonce, then call the Squads multisig program.S-Curve read of the Solana ledger: the two Drift attack transactions and their nonce accounts. Squads is a shared-approval wallet that, BlockSec wrote, is “a common on-chain governance system on Solana,” and Drift’s administrators used it.BlockSec, Drift Protocol incident analysis. They landed four slots apart, about a second.

Each transaction was tied to its own nonce account. The first account was set up at 01:22 UTC on 24 March and used once, by the first attack transaction at 16:05 UTC on 1 April. The second was set up on 31 March and used once, by the second transaction a second later. A transaction signed against a nonce account stays valid until the account’s stored value changes. Neither account was touched between its setup and the attack: each has two transactions in its history, “initialization and the attack”.

BlockSec, a blockchain security firm, wrote two days after the theft that the attacker “induced two of five Security Council multisig signers to pre-sign malicious governance transactions through phishing or misleading signing requests”. It described the property that made the wait possible: “once a signer approves a durable nonce transaction, they cannot revoke their signature unless the nonce authority manually advances the nonce account”. Once in control, BlockSec wrote, “the attacker introduced a malicious collateral asset” and drained the platform through its lending functions.

Drift set new signing rules for its relaunch. “Durable nonces will be disabled for all signers,” its 16 April update says. “Timelocks will be enforced on all critical administrative actions,” it adds, so that an approved change waits before it runs.

Why the developers want it gone

The proposal never mentions Drift. Its case is the cost of keeping two kinds of transaction in the same machine. The special rules nonces need, it says, “have repeatedly caused security vulnerabilities and consensus bugs in validator clients”. It lists incidents from 2019 to 2026, among them one in 2022 in which “A failed transaction was processed through both the blockhash and nonce paths, halting mainnet for about 4.5 hours”.

There is a second cost. “Nonce transactions never expire, so resending them is free,” the Foundation’s page says. Max Resnick, a researcher, counted them in one epoch in June: “16.1M / 521M txs are durable nonce (~3.1%),” and “1,975 / 6,621 SOL in priority fees come from nonce txs (~30%)”.Max Resnick, Soft Deprecation For Nonce Transactions, SIMD discussion 564, June 2026. Priority fees are the tips senders add to be processed first. “Those 555 account for 97.5% of nonce txs,” he wrote, out of 103,672 accounts that paid for nonce transactions. He described the feature as “coopted for durable nonce spam”.

What custodians must rebuild

The replacement moves the waiting out of the protocol and into an ordinary program. The owner moves control of its accounts to an address the program governs; then, the proposal says, “The owner then signs an authorization offline, which a relayer later submits in an ordinary transaction”. The program checks the signature on chain and carries out the approved instructions. Two such programs are being built, Anza’s Programmatic Signer and Blueshift’s Vector. The Foundation lists Anza’s as “deployed on Devnet (pre-audit),” Devnet being Solana’s test network.

The work is large. Custodians and issuers told the Foundation that “Millions of token and stake accounts need new authorities”. Some of their own rules cut against the design: cold storage policies, the Foundation notes, often forbid any smart contract between the key and the funds. The Foundation answers that both programs are small and open source and can be audited or deployed by the custodian itself. “Institutions asked for 6 to 12 months after mainnet availability,” it says.

The two documents disagree on timing. The proposal sets a floor of 5 May 2027, six months from its publication. The Foundation’s page gives the expected mainnet date as “Roughly six months after the replacement program is ready. No date set”. The proposal is still a draft; CoinDesk reported it needs sign-off from at least one engineer at Anza and one at Firedancer, the rival validator software, before it can be merged. Once it is active, the proposal says, “A DNT signed before activation can never become valid after it”, meaning any durable nonce transaction still waiting dies with the rule.

The same property, moved

The proposal is direct about where the danger goes. “Risk moves to replacement programs,” it says, which must handle signature checks, replay protection, expiry and revocation themselves. One warning reads like a lesson from April: “A failed execution can leave an authorization usable, so a failed submission is not a revocation”.

And the new programs keep the feature that made the wait possible. “Neither program has a built-in expiry,” the Foundation’s page says. “A signed message stays valid until it is used or cancelled”. The page suggests adding a deadline instruction where one is wanted. Under the replacement, whether a signature ever goes stale becomes a setting each custodian chooses.