Aptos launches optional Encrypted Mempool on mainnet to curb sandwich attacks
In brief
- Aptos said its opt-in Encrypted Mempool went live on mainnet on Monday.
- Assets and amounts stay hidden until ordering is final; sender address and gas fee stay visible.
- Encrypted transactions carry a minimum gas price twice the network's base minimum, per Aptos docs.
- Aptos reported about 20 milliseconds of added latency per block in 50-node tests.
How the encryption works
When a user opts in, a compatible wallet or app encrypts the transaction's contents on the user's device before it's sent to Aptos, according to Aptos' description of the feature. Assets and amounts stay hidden. The sender's address and gas fee don't.
Validators agree on transaction order while blind to the contents. Once ordering is finalized, they decrypt the transactions together (no single validator can open a pending transaction alone).
“When you send a transaction on any major chain today, anyone watching the network can see the details before it executes, the function you’re calling, the assets and amounts involved, and the contracts you’re interacting with,” Aptos said.
Aptos said it built the feature for institutions submitting large transactions, traders looking to avoid MEV risk, AI agents and builders. (Cointelegraph also ran a related headline on Aptos committing $50 million to an AI agent infrastructure push.)
What it costs
You pay for the privacy. Aptos' developer documentation sets the minimum gas price for encrypted transactions at twice the network's base minimum, and the company said the system added about 20 milliseconds per block in tests with 50 nodes, compared with its existing consensus implementation.
Those latency numbers come from Aptos' own testing.
Why MEV protection matters
Sandwich attacks cost Ethereum traders about $60 million over the 12 months through October 2025, according to Cointelegraph's analysis of EigenPhi data. On Solana, Bitquery found that sandwich attacks generated $29.7 million for bots over an 11-month period, across nearly 6.9 million attacks affecting about 2.2 million wallets.
Aptos isn't the only chain going after the problem. Gnosis Chain launched an encrypted mempool using Shutter in July 2024, while Ethereum's Flashbots Protect routes transactions privately to block builders. Aptos said its approach is different because its existing validators handle both ordering and decryption, so there's no separate decryption committee and no trusted builders in the loop.
Frequently asked questions
How does Aptos' Encrypted Mempool hide transactions?
When a user opts in, a compatible wallet or app encrypts the transaction's contents on the user's device before sending it to Aptos. Validators agree on transaction order without seeing the contents, then decrypt the transactions together once ordering is finalized. No single validator can decrypt a pending transaction alone.
What details stay visible in an encrypted Aptos transaction?
Assets and amounts stay hidden while the transaction is pending. The sender's address and the gas fee remain visible.
Does using the Encrypted Mempool cost more?
Yes. Aptos' developer documentation sets the minimum gas price for encrypted transactions at twice the network's base minimum. Aptos also said the system added about 20 milliseconds per block in tests with 50 nodes, compared with its existing consensus implementation.
How is Aptos' approach different from Shutter or Flashbots Protect?
Gnosis Chain uses Shutter for its encrypted mempool, and Ethereum's Flashbots Protect routes transactions privately to block builders. Aptos said its design differs because its existing validators handle both ordering and decryption, without a separate decryption committee or trusted builders.
