Aptos has switched on an encrypted mempool on its main network, letting users hide what a transaction does until the block containing it is final. The feature went live on Monday, the Aptos Foundation said in a blog post, and is optional for each transaction.
A mempool is the waiting room where pending transactions sit before validators, the computers that confirm transactions, put them into a block. On most chains anyone can read that waiting room, which lets bots see a trade coming and place their own orders around it.
That practice is known as MEV, short for maximal extractable value: profit taken by reordering, inserting or copying other people’s transactions. Front-running and so-called sandwich attacks, which buy just before a user’s trade and sell just after it, are the familiar forms.
Under the Aptos design, a user’s wallet encrypts the transaction payload, meaning the function being called and its arguments, before sending it. The sender’s address and the fee stay visible.
The block leader proposes an order while blind to the contents. Only after consensus finalises the block do validators jointly decrypt the batch, and then the transactions run.
Decryption needs validators holding at least two-thirds of the network’s stake, the same majority that signs off every block, according to the post. One validator alone, or any smaller group, cannot read a waiting transaction. “This means no additional trust,” the foundation wrote, because the validators that order blocks are the same ones holding the decryption shares.
The cryptography behind it is a batched threshold encryption scheme specified in AIP-144. Aptos says it adds about 20 milliseconds per block in its own 50-node benchmarks, against block finality of under a second. The implementation was reviewed by the security firm ZKSecurity.
Why it matters: MEV protection on most networks today relies on someone extra seeing the transaction first, such as a private block builder, a hardware enclave or a separate key committee. Aptos is pitching a version that asks users to trust only the validator set they already rely on.
Who still sees what
The privacy is narrow by design. Version one hides the payload, not the sender or the fee, and every transaction is written to the chain in readable form once the block is final, so the ledger stays auditable.
It is also opt-in. Petra is the first wallet to offer encryption in its signing screen, and Decibel, a perpetual futures exchange built on Aptos, says it will use it to keep orders private until they execute, according to the post. Developers get it through the Aptos TypeScript SDK from version 7.0.0, and existing Move smart contracts need no changes, the developer docs say.
The approach shifts the risk rather than removing it. If validators holding two-thirds of stake colluded, they could read pending transactions early, though that is the same majority the chain already depends on to agree on blocks. “The Aptos approach requires you to trust only who you were already trusting,” the post says.
Aptos has not published usage figures for the feature since launch.
Other networks attack the same problem differently. The post lists Flashbots Protect, a private relay used on Ethereum, and Shutter, an outside key committee on Gnosis Chain, as the main alternatives. For more layer-1 changes this month, see this week’s Chain Check and our report on the XRP Ledger’s patched payment bug.
APT was little changed at $0.837 as of 19:54 UTC, according to CoinGecko. The next thing to watch is how many wallets and trading apps beyond Petra and Decibel switch encryption on.
This article is for information only and is not investment advice.