Aptos Launches Encrypted Mempool on Mainnet to Stop Frontrunning and Sandwich Attacks

Published October 13, 2026, 4:40 PM PKT. Based on Aptos's official announcement on X (Oct. 12, 2026), plus reporting by Cointelegraph, CoinCentral and AltcoinBuzz.

Layer-1 blockchain Aptos has launched Encrypted Mempool on its mainnet, an optional feature that hides pending transaction details from trading bots until validators finalize block ordering. The network announced the launch on October 12, saying the goal is to cut the frontrunning and sandwich attacks that make up the most visible forms of maximal extractable value, or MEV.

The opt-in design means the feature changes nothing for users who do not touch it. Those who do get a way to stop bots reading their orders before execution, but the order costs more: encrypted transactions pay double the base gas minimum plus a flat decryption fee.

How the encrypted mempool works

When a user opts in, a compatible wallet or app encrypts the transaction's contents on the device before sending it to Aptos, Cointelegraph reported. The function being called, the assets and amounts involved all stay hidden. The sender's address and the gas fee remain visible.

The encrypted transaction enters the mempool, where pending transactions wait for block inclusion. Validators agree on the order of transactions while being blind to their contents. Once ordering is finalized, validators collectively decrypt the transactions and execute them onchain. No single validator can decrypt a pending transaction on its own.

Aptos pitched the tool at institutions submitting large transactions, traders wanting to avoid MEV risk, AI agents and blockchain builders. "When you send a transaction on any major chain today, anyone watching the network can see the details before it executes," Aptos said in its announcement, adding that "bots use that visibility to trade against you or copy your strategy."

The price of privacy: twice the gas

Encrypted transactions carry a minimum gas-unit price of 200 Octas per unit, twice the network's base minimum of 100 Octas, plus a flat 375 gas units charged for decryption, according to Aptos's developer documentation cited by AltcoinBuzz. AltcoinBuzz worked through the numbers: a simple transfer using 150 gas units costs 15,000 Octas in the clear, but encrypted it costs about 105,000 Octas, or 0.00105 APT, roughly seven times the bill.

Aptos's tests also found the feature adds approximately 20 milliseconds of latency per block in 50-node test setups, according to reporting by CoinDesk. The extra cost and delay are the direct trade of the privacy: the decryption work has to be paid for somewhere, and validators spend time on it.

MEV is a $60 million problem

Sandwich attacks, one form of MEV attack in which a bot front-runs and back-runs a victim's trade to skim profit, cost Ethereum traders about $60 million over the 12 months through October 2025, according to Cointelegraph's analysis of EigenPhi data. On Solana, sandwich attacks generated $29.7 million for bots over an 11-month period examined by Bitquery, which identified nearly 6.9 million attacks affecting about 2.2 million wallets.

Aptos's move comes as the industry debates how to defend against AI-accelerated versions of these attacks. Ethereum researcher Justin Drake recently urged a crypto "bunker mode" over warnings that AI could threaten wallet cryptography, and Starknet is weighing becoming a quantum-resistant L1 by 2027. Encrypted mempools are one of the few defenses that ship today: users get concrete protection per transaction rather than a future protocol upgrade.

Petra is first to support it

A wallet has to support the feature for users to opt in. Petra, Aptos's flagship wallet, is the first to fold the encrypted mempool into its signing flow, according to AltcoinBuzz. Decibel is listed as a planned user, and the Aptos TypeScript SDK can handle the encryption from version 7.0.0 onward.

The market reaction was muted. CoinCentral reported that the APT token traded at $0.7995, down 11.5% over 24 hours, according to CoinGecko, on the day of the announcement. The launch arrives amid Aptos's scheduled October 12 token unlock, so the price move does not read cleanly as a verdict on the feature.

This article is news reporting and is not investment advice.

Sources

• Aptos, official announcement on X (Oct. 12, 2026), primary source for the Encrypted Mempool mainnet launch, the opt-in design, and the target audience of institutions, traders, AI agents and builders
• Cointelegraph, Aptos Launches Encrypted Transactions to Combat MEV Attacks (Oct. 13, 2026), secondary source for the mechanics of the encrypted mempool, the "bots use that visibility" framing, and the sandwich attack figures ($60 million on Ethereum via EigenPhi analysis, $29.7 million on Solana via Bitquery)
• CoinCentral, Aptos Launches Encrypted Mempool on Mainnet to Stop MEV Attacks (Oct. 13, 2026), secondary source for the gas pricing (200 Octas per unit, double the base minimum), the 20-millisecond latency finding, and the APT token price of $0.7995 on announcement day per CoinGecko
• AltcoinBuzz, Aptos Encrypted Mempool Is Live: What It Costs Traders (Oct. 13, 2026), secondary source for the developer documentation fee details (flat 375 gas units for decryption), the 7x cost worked example, and the Petra, Decibel and TypeScript SDK v7.0.0 integration details