EIP-8105: A new design for Ethereum encrypted memory

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Sandwich attacks cost Ethereum users an estimated $60 million a year. Transactions submitted to the public are publicly visible before they are embedded, giving MEV bots the ability to manipulate the transaction sequence and insert their own for profit. Despite years of discussion and various attempts at extra-protocol punishment, this problem persists to some extent.

Encrypting Mempool transactions is one of the most compelling solutions to prevent MEV. While this idea has been actively discussed for years, it has yet to be implemented at the protocol level. In our previous research, we investigated several threshold-encryption-based proposals, including Shutter, Batched Threshold Encryption, and Flash Freezing Flash Boys. In this article, we turn to a meta-proposal titled “Universal Encrypted Mempool (EIP-8105)”.

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How to handle EIP-8105 membrane encryption

The Universal Encrypted Mempool, also known as the EIP-8105, is a scheme-agnostic encrypted mempool design, which means it can support a variety of encryption methods, including initial encryption, MPC committees, TEs, delayed encryption, and fully homogeneous encryption. To facilitate this dynamic design, a new system contract is proposed at the implementation layer, called the key provider registry. It allows any account to register as a key provider that holds and publishes decryption keys using their preferred encryption technology.

How transactions are carried out in the Universal Encrypted Mempool

Universal Encrypted Mempool introduces two new transaction types under the EIP-2718 framework: 0x05 for encrypted transactions and 0x06 for encrypted transactions. An encrypted transaction is an envelope with an encrypted payment and public payment, which contains the envelope nono, gas volume, gas price parameters, key supplier ID, key ID and signature. This structure is required to match the transaction with the selected key supplier, assign the NONO and ensure that the gas charges for the wall area are covered.

EIP-8105 follows a two-step execution flow. In the first step, the encrypted transaction envelope is included in the block, although the payment itself remains hidden. Key providers monitor transactions through encrypted payloads, collect relevant transaction key IDs, and provide corresponding decryption keys or decryption keys once the blockchain has published the data.

Once the block developer publishes the execution fee, the relevant key provider will display a decryption key or discount announcement. The Payload Timeliness Committee (PTC) monitors the timeliness of decryption keys referenced in encrypted transactions, verifies them, and verifies whether or not a valid key exists. If the key exists and decryption succeeds, the resulting decrypted transaction is executed in the following block. If the key is lost, blocked, or decryption fails, the decryption fee is skipped, the postage is intact and the transaction fee is still paid.

EIP also enforces a blocking structure that prevents MEV-extracting transactions from entering the window between decryption and execution. Decrypted transactions should appear at the beginning of the block, opaque transactions remain in the middle, and encrypted transactions are placed at the end. This prescription allows encrypted payloads to be revealed and executed only after they have been embedded, preventing secondary MEV.

While EIP-8105 significantly limits MEV exposure, early providers in the block have limited ability to decipher MEV from later transactions or hold their keys. The proposal attempts to alleviate this by allowing key suppliers to name other trusted suppliers and ordering transactions through the resulting key supplier trust graph.

Encrypted Mempools and Ethereum's Roadmap

Encrypted mempools are becoming an increasingly important part of Ethereum's roadmap, as the ecosystem seeks protocol-level ways to mitigate harmful MEV. While EIP-8105 is set to be one of the headlines for the first 2027 hard fork, it remains an open draft, and the ideas continue to inform the broader effort to develop a major encrypted-mempool proposal for the upgrade.