Aptos has activated an optional encrypted mempool on mainnet, allowing users to conceal transaction payloads until validators have finalized their ordering. The October 12 rollout is designed to reduce frontrunning and sandwich attacks by preventing block proposers from seeing the economic intent of pending transactions before deciding where they appear in a block. The feature is implemented through AIP-144 and operates directly inside Aptos consensus.
According to Aptos’s official mainnet announcement, users encrypt transaction payloads locally before submission using an encryption key jointly generated by validators for each epoch. The block proposer orders those ciphertexts without seeing the underlying function or arguments, and validators collectively decrypt them only after consensus fixes the block. No single validator, or group controlling less than the required stake threshold, can independently decrypt a pending transaction.
Aptos Moves MEV Protection Into Consensus
AIP-144 uses batched threshold encryption to avoid running a separate decryption protocol for every individual transaction. Validators instead produce shares that allow an entire confirmed batch to be decrypted efficiently after ordering. The design keeps the decryption committee identical to the validator set, avoiding the additional trust assumption created by external builders or independent key-holder committees. Aptos reported roughly 20 ms of additional latency per block in 50-node benchmarks against its production AptosBFT implementation.
That model differs from systems that expose order flow to specialized intermediaries before execution. The value of early blockchain data is already visible in infrastructure built for validator-level feeds targeting market makers and MEV searchers. Aptos attacks the problem by withholding the actionable payload until transaction order can no longer be rearranged around its contents, although senders, gas parameters and other metadata remain publicly observable.
The protection also has a measurable cost. Aptos documentation sets the minimum gas-unit price for encrypted transactions at 200 octas, twice the usual network minimum, to compensate validators for additional decryption work. Encryption is therefore an optional execution premium rather than a network-wide default, leaving ordinary transactions on the existing path when confidentiality is unnecessary.
Security Review Defines the Privacy Boundary
zkSecurity conducted a four-week independent review of the encrypted mempool implementation, covering the threshold-encryption scheme, distributed key generation and consensus integration. The audit identified issues ranging from cryptographic verification weaknesses to transaction-integrity and liveness concerns, with Aptos marking numerous findings as fixed during the review. The audit also documented inherent privacy limitations that remain part of the architecture rather than software bugs.
Those limitations include visible sender information, sequence numbers, gas settings and ciphertext length, which can leak contextual information about pending activity. An optional field can also reveal the targeted contract before decryption, while validators retain discretion over whether encrypted transactions are included in blocks. Encrypted mempool therefore protects transaction intent during a critical execution window, but it does not make Aptos transactions anonymous or permanently confidential.
Petra is the first wallet to expose encryption directly within its signing flow, while developers can access the functionality through the Aptos TypeScript SDK version 7.0.0 and later without modifying existing Move contracts. Decibel also plans to use the system for perpetual-futures orders. Wallet and application integration now becomes the practical adoption layer, because mainnet activation alone does not mean that ordinary Aptos transactions are automatically encrypted.
The rollout adds another approach to a wider industry effort to reduce execution disadvantages before settlement. Ethereum development has explored measures including proposer-builder separation and MEV-related protocol changes, while wallet research has focused on verifiable transaction simulation before signing. Aptos’s contribution is narrower: it changes what validators can learn about transaction payloads before ordering, while preserving public execution and auditability after confirmation.
