Aptos Launches Encrypted Mempool to Stop Frontrunning and Sandwich Attacks

Layer-1 blockchain Aptos has activated a new optional feature on its mainnet designed to protect traders from maximal extractable value (MEV) attacks such as frontrunning and sandwich attacks. The Encrypted Mempool keeps pending transactions hidden until their position in a block is locked in.

Who Benefits From MEV Protection

Aptos says the tool suits institutions moving large sums, everyday traders worried about MEV, plus AI agents and developers. Today, anyone monitoring a network can view transaction details before execution, letting bots trade against users or copy their moves. Sandwich attacks alone drained roughly $60 million from Ethereum traders in the year to October 2025, while bots on Solana pulled $29.7 million across 11 months, hitting about 2.2 million wallets.

How Encrypted Mempool Works

Opting in means a compatible wallet encrypts transaction contents locally. Assets and amounts stay concealed, though the sender address and gas fee remain public. Validators order transactions without seeing what’s inside, then decrypt them together once ordering is final. No validator can unlock a pending transaction alone.

Costs and Network Performance Trade-Offs

Protection isn’t free. Encrypted transactions pay at least double the base gas minimum, and tests with 50 nodes showed roughly 20 milliseconds added per block.

Unlike Gnosis Chain’s Shutter system or Ethereum’s Flashbots Protect, Aptos uses its existing validators for both ordering and decryption, avoiding separate committees or trusted builders.