Key facts
- Aptos has launched its Encrypted Mempool feature on its mainnet.
- The feature encrypts transaction details until their order is finalized, preventing bots from seeing and exploiting them.
- This aims to protect users from frontrunning and sandwich attacks, forms of maximal extractable value (MEV).
- The protection comes with a higher gas fee (twice the base minimum) and a small delay.
- Aptos validators handle both the ordering and decryption of transactions.
Layer-1 blockchain Aptos has introduced its Encrypted Mempool feature, designed to shield traders from maximal extractable value (MEV) attacks such as frontrunning and sandwich attacks. The optional feature, now live on its mainnet, allows users to encrypt pending transactions until their order within a block is finalized.
According to Aptos, the visibility of transaction details on most blockchains allows bots to exploit pending trades. Sandwich attacks alone have cost Ethereum traders approximately $60 million over a 12-month period, and on Solana, such attacks generated nearly $30 million for bots over an 11-month span, affecting millions of wallets.
When a user opts into Aptos' Encrypted Mempool, their wallet or application encrypts the transaction details before it is sent. While the sender's address and gas fee remain visible, the specific assets and amounts are hidden. These encrypted transactions enter the mempool, where validators agree on their order without knowing the contents. Once ordered, validators collectively decrypt the transactions for execution and on-chain recording, with no single validator able to decrypt a pending transaction independently.
This protection comes with additional costs, including a minimum gas price set at twice the network's base minimum. Aptos also noted that the system adds approximately 20 milliseconds per block in tests involving 50 nodes.
Aptos joins other networks in offering MEV protection. Gnosis Chain launched an encrypted mempool in July 2024, and Ethereum's Flashbots Protect offers private transaction routing. Aptos differentiates itself by having its existing validators manage both transaction ordering and decryption, rather than relying on a separate decryption committee or trusted builders.