A Aptos announced on Monday (12) the activation of Encrypted Mempool on its mainnet. The feature allows hiding the content of transactions while they await processing, making it harder for bots that exploit pending operations to execute strategies of front-running and sandwich attacks.
The protection is optional and works directly on the blockchain protocol, without relying on external intermediaries. However, the encryption does not offer complete anonymity: certain information remains accessible even before the transaction is confirmed.
The mechanism encrypts data on the user's device before sending it to the network. Validators determine the order of operations without knowing their content and only perform collective decryption after the block is finalized.
This sequence prevents network participants from checking the details of a trade in advance to position other transactions based on it. The protection, however, does not eliminate all possibilities of exploitation related to the ordering of operations.
Address and fees remain visible before execution
The Aptos documentation establishes an important distinction: the sender's address and the fields referring to the gas fee remain visible while the transaction awaits processing.
Encryption protects the payload, which includes the smart contract function invoked and its arguments, such as the parameters of a trade. After the final determination of the block order, this information is revealed to allow execution and the public record of the operation.
The feature also has additional costs. Encrypted transactions require a minimum price of 200 octas per unit of gas, equivalent to twice the network's basic minimum. There is also a fixed charge of 375 gas units for the decryption process.
For developers, the feature is available in the Aptos TypeScript SDK starting with version 7.0.0, with no need to modify existing smart contracts. The Petra wallet already offers an encryption option during transaction signing.
The implementation uses Aptos's own validators to order and decrypt operations, eliminating the need for an external committee responsible for data access.
In the tests released by the project, conducted with 50 nodes, the mechanism added approximately 20 milliseconds per block to processing. The result corresponds to a benchmark conducted by the developers and does not constitute an independent measurement of performance on the mainnet.
With the activation, the protection becomes available to compatible applications and users, but its use depends on the choice to encrypt each transaction.
