Aptos has introduced an optional encrypted mempool on mainnet designed to make it harder for bots and other actors to exploit pending trades through frontrunning and sandwich attacks.
Under the new system, users who opt in can submit transactions through compatible wallets or applications that encrypt transaction contents on the device before they are sent to the network. Aptos said this keeps key trade details hidden until transaction ordering has been finalized.
How the encrypted flow works
In a standard mempool, pending transactions are visible before they are included in a block. Aptos’ encrypted version changes that process for users who choose it. The network can still receive and queue the transaction, but the contents are obscured while it is waiting to be ordered.
According to the rollout description, information such as the assets involved and the transaction amounts remains concealed. Validators are still able to see the sender’s address and the gas fee attached to the transaction, but not the trade details themselves.
Validators then order encrypted transactions without access to their contents. Only after that ordering step is complete are the transactions decrypted and executed onchain.
Targeting frontrunning and sandwich attacks
The main goal is to reduce a common source of extractable value in public blockchains: the ability to inspect pending orders and trade around them. When pending transaction data is visible, bots can attempt to insert their own transactions ahead of a user’s order or place trades before and after it.
By hiding order details until sequencing is complete, Aptos aims to block that visibility window. The intended effect is to stop outside parties from reading pending trades and using that information to profit at the submitting user’s expense.
The feature is optional rather than mandatory, meaning its use depends on whether traders and the applications they rely on choose to support it.
Cost and performance trade-offs
The added privacy comes with a higher minimum fee. Aptos said encrypted transactions must pay at least twice the network’s base minimum gas price.
There is also a latency cost, though the network described it as limited. In tests involving 50 nodes, the encrypted mempool added about 20 milliseconds per block.
Those trade-offs suggest Aptos is positioning the feature as a protection tool for users willing to accept somewhat higher execution costs in exchange for shielding transaction details during the ordering phase.
What sets the design apart
Aptos said its implementation differs from some other approaches to transaction privacy and ordering. Rather than introducing a separate decryption committee or relying on trusted builders, the network’s existing validators handle both ordering and decryption.
That design choice keeps the workflow inside the validator set already responsible for block production. The next concrete step will be broader support from wallets and applications, since users can only opt in through compatible software that performs encryption before submission.
Source: cointelegraph.com