Aptos launches opt-in encrypted mempool on mainnet

20 milliseconds is the added per-block latency Aptos reports for its new Encrypted Mempool, now live on mainnet. That figure comes from a 50-node benchmark against the network’s existing consensus implementation. By hiding trade instructions until a block’s order is final, the feature aims to make it harder for bots to exploit your pending transactions.

Aptos announced the launch on Oct. 12, describing the feature as an optional way to protect transactions from maximal extractable value (MEV), including frontrunning and sandwich attacks. In a mainnet launch announcement, Aptos says the payload is encrypted on the user’s device and decrypted only after block finalization. Cointelegraph reports that Aptos built the feature for institutional transactions, traders, AI agents and builders.

What stays hidden while your transaction is pending?

The called function and its arguments are encrypted; your sender address and gas-fee fields remain visible. Validators agree on transaction ordering while unable to read the payload. After consensus finalizes the block, validators collectively decrypt the transactions, which then execute and are recorded onchain.

Aptos says the validator set jointly generates a new encryption key each epoch. No single validator can decrypt a pending transaction, and decryption requires the same two-thirds honest-stake threshold used to produce blocks. That means the feature relies on the chain’s existing validator trust model, rather than adding a separate decryption committee.

How does encryption target sandwich attacks?

A sandwich attacker watches a pending trade, then tries to place transactions around it to profit from the price movement. Hiding the trade’s instructions and amounts until its order is fixed is intended to deny bots that advance view. It reduces exposure to this kind of attack; Aptos has not said it eliminates every form of MEV.

What does opting in cost, and where can you use it?

Encryption is optional for each transaction, so ordinary transactions are not automatically hidden. According to Cointelegraph’s report, encrypted transactions require a minimum gas price twice the network’s base minimum. Aptos’s benchmark found roughly 20 milliseconds of added latency per block with 50 nodes.

Petra is the first wallet Aptos says offers encryption in its signing flow. The Aptos TypeScript SDK version 7.0.0 and later can fetch the current epoch key and encrypt payloads; existing Move smart contracts need no changes. Aptos says the perpetual futures exchange Decibel plans to use the feature to keep orders private until execution. Once a block is final, transaction data is visible onchain as usual.

References

• mainnet launch announcement — aptosnetwork.com
• Cointelegraph’s report — cointelegraph.com