Aptos rolls out Encrypted Mempool to curb frontrunning, sandwich attacks
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Written by
Simonas Brazionis - Updated 2026-10-16 02:35:03
The Aptos Layer-1 blockchain has introduced an optional feature, Aptos rolls out Encrypted Mempool, designed to protect traders from maximal extractable value (MEV) attacks, specifically frontrunning and sandwich attacks.
On Monday, Aptos announced the activation of its Encrypted Mempool feature on its mainnet. This allows users to choose to keep pending transactions encrypted until their final block ordering is established.
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Understanding MEV and Its Impact
Aptos explained that on most major blockchains, network observers can view transaction details, including function calls, asset amounts, and contract interactions, before execution. This visibility enables bots to trade against or emulate user strategies.
Data from Cointelegraph, based on EigenPhi analysis, showed that sandwich attacks, a form of MEV, cost Ethereum traders approximately $60 million between October 2024 and October 2025. Similarly, Bitquery data revealed that bots generated $29.7 million from nearly 6.9 million sandwich attacks affecting about 2.2 million wallets on Solana over an 11-month period.
How Aptos' Encrypted Mempool Works
When a user opts into the Encrypted Mempool, a compatible wallet or application encrypts the transaction's contents on the user's device before transmission to Aptos. While details such as assets and amounts remain concealed, the sender's address and gas fee are still visible. Choosing the right crypto wallets is crucial for securely managing digital assets and interacting with blockchain applications.
The encrypted transaction then enters the mempool, where pending transactions await inclusion in a block. Validators determine the order of these transactions without knowledge of their content. Once the ordering is finalized, validators collectively decrypt and execute the transactions, which are then recorded on-chain. No single validator can decrypt a pending transaction independently.
Costs and Network Performance
By concealing transaction details until ordering is fixed, the system aims to prevent bots from identifying pending orders and inserting trades to profit at users' expense. This protection, however, introduces additional costs and a slight delay.
According to Aptos' developer documentation, encrypted transactions incur a minimum gas price that is double the network's base minimum. Aptos also reported that tests with 50 nodes showed the system added approximately 20 milliseconds per block compared to the existing consensus implementation.
Aptos' Approach to MEV Protection
Aptos joins other networks in offering MEV protection. Gnosis Chain launched an encrypted mempool with Shutter in July 2024, and Ethereum's Flashbots Protect privately routes transactions to block builders.
Aptos differentiates its approach by having its existing validators manage both transaction ordering and decryption, thereby avoiding reliance on a separate decryption committee or trusted builders. The Aptos rolls out Encrypted Mempool initiative represents a significant step in enhancing transaction privacy and security on the platform.
