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ZEC $1,227 Aptos launches mainnet Encrypted Mempool to block MEV attacks
The optional Layer-1 feature hides pending transaction details until block ordering is finalized to reduce frontrunning and sandwich attacks.
Key takeaways
- MEV attacks cost millions. Sandwich attacks cost Ethereum traders about $60 million over 12 months through October 2025, and 6.9 million such attacks hit 2.2 million Solana wallets.
- Encrypted transactions have higher gas fees. Encrypted Aptos transactions require a minimum gas price twice the network's base minimum, plus extra decryption fees.
- Latency increase is ~20 milliseconds. Aptos' tests found the Encrypted Mempool adds approximately 20 milliseconds of latency per block in 50-node tests.
What happened
On October 12, 2026, Layer-1 blockchain Aptos launched its optional Encrypted Mempool feature on mainnet to reduce maximal extractable value (MEV) risks including frontrunning and sandwich attacks. The feature hides pending transaction details until validators finalize their block ordering, preventing bots from exploiting visible trade data to profit at users' expense.
When a user opts in, a compatible wallet or app encrypts the transaction's contents on their device before sending it to the network. Details such as the assets, amounts and smart contract functions called remain hidden, while the sender's address and gas fee stay publicly visible. Validators agree on transaction order without seeing the hidden contents, then collectively decrypt and execute transactions once block ordering is finalized, with no single validator able to decrypt a pending transaction on its own.
Aptos said the feature was built for institutions submitting large transactions, traders wanting to avoid MEV risk, AI agents and blockchain builders.
Why it matters
Sandwich attacks, a common MEV exploit, have already cost traders significant sums across major blockchains. The attacks cost Ethereum traders about $60 million over the 12 months through October 2025, while 6.9 million sandwich attacks on Solana affected roughly 2.2 million wallets over an 11-month period, per Bitquery data. Aptos' tool offers a protocol-native alternative to existing MEV protection solutions that rely on external decryption committees or private block builders.
The protection comes with added costs and minor latency. Encrypted transactions require a minimum gas price twice the network's base minimum, plus extra fees for decrypting transaction payloads. Aptos' tests with 50 nodes found the system adds approximately 20 milliseconds of latency per block compared to its standard consensus implementation.
Background
Aptos joins other networks offering protection against harmful MEV, including Gnosis Chain which launched an encrypted mempool using Shutter in July 2024, and Ethereum's Flashbots Protect which routes transactions privately to block builders.
Questions readers ask
What is Aptos Encrypted Mempool?
Aptos Encrypted Mempool is an optional mainnet feature that encrypts pending transaction details on users' devices before they are sent to the network. Transaction contents remain hidden from validators and outside observers until block ordering is finalized, at which point validators collectively decrypt and execute the transactions. Sender addresses and gas fees stay visible throughout the process.
Does Aptos Encrypted Mempool cost more to use?
Yes, encrypted transactions require a minimum gas price twice the network's base minimum, plus additional fees for decrypting transaction payloads. The feature also adds approximately 20 milliseconds of latency per block in tests with 50 nodes.
How does Aptos Encrypted Mempool prevent sandwich attacks?
By hiding pending transaction details like asset amounts and smart contract functions until block order is finalized, the feature prevents trading bots from spotting large pending trades and inserting orders ahead of or after them to profit from price movement.
