Sandwich attacks happen when a bot sees your pending trade in the public mempool, buys before it and sells after it. An Ethereum encrypted mempool would hide a transaction’s contents until a block builder has committed to its position. EIP-8184, named LUCID, is the leading draft for this. It is a proposal only, and it is not scheduled for any upgrade.
Public mempool versus LUCID
| Question | Public mempool today | With LUCID (draft) |
|---|---|---|
| Who sees the trade? | Anyone, including bots, while it is pending | Builders bid on commitments and never see the contents |
| What the sender submits | A readable transaction | A “sealed transaction”: a signed ticket that pays fees and uses the sender’s nonce, plus an encrypted payload kept off-chain |
| When contents are revealed | Immediately | After the beacon block is attested, a key publisher releases the decryption key, and the transactions run at the start of the next block |
| Fees | Paid when included | Prepaid through the ticket, with unused gas refunded |
The EIP page lists Anders Elowsson, Justin Florentine and Julian Ma as authors. It was created on March 4, 2026 and has Draft status. It requires EIP-7805 (FOCIL), the inclusion-list mechanism.
The design does not fix one encryption scheme. Decryption can happen off-protocol, including self-decryption by the sender. CryptoSlate adds that the encrypted segment is capped at one-eighth of the block gas limit, with a reservation fee that is mostly refunded after successful decryption.
Why It Matters to You
If you trade on Ethereum, a working encrypted mempool could make it harder for bots to sandwich your orders. Today it helps nobody directly: it is a draft with no target fork, and you cannot use it through the Ethereum protocol. Some private order-flow services exist outside the protocol, but we did not evaluate them here.
Is it scheduled?
No. The EIP page names no target fork. Ethereum.org lists FOCIL (EIP-7805) and frame transactions (EIP-8141) as the scheduled Hegotá headliners, with mainnet expected in Q2 2027 and the date not confirmed. LUCID is not on that list, so it should not be described as expected in Hegotá. CryptoSlate reported that developers would discuss encrypted mempool proposals on a call on August 19, 2026.
| Item | Status | Source |
|---|---|---|
| EIP-8184 (LUCID) | Draft, no target fork | eips.ethereum.org |
| FOCIL (EIP-7805) | Scheduled for Hegotá | ethereum.org |
| Alternative, EIP-8105 | Draft, trust-graph approach | CryptoSlate |
Where it falls short
No source we opened gives the current dollar cost of sandwich attacks. CryptoSlate says only that estimated MEV losses have declined from earlier peaks. More important, CryptoSlate reports that no known cryptographic construction meets all of the design’s requirements at Ethereum’s scale: small public keys, non-interactive decryption, no trusted setup, practical ciphertext sizes, chosen-ciphertext security and a route to quantum safety. The EIP page says only ECDSA signatures are valid today, which is not post-quantum safe.
Proving why a decryption key failed to arrive, or whether a publisher leaked it early, is unresolved. The page also flags risks of committee bribery, differing builder pre-states and denial of service through low-fee sealed transactions. Some sections are marked TODO.
Questions people ask
Will an encrypted mempool stop front-running completely?
Not on its own. LUCID aims to limit it by hiding order flow until commitment. The EIP itself lists unresolved risks.
What is FOCIL?
FOCIL, EIP-7805, spreads inclusion decisions across many validators so one builder cannot keep a valid transaction out. LUCID extends it.
Can I use an encrypted mempool today?
Not through the Ethereum protocol. This is a draft. Some private order-flow services exist outside the protocol, but we did not evaluate them here.
Is this financial advice?
No. It explains a proposal and does not recommend any trade.
Sources
- Ethereum Improvement Proposals: EIP-8184, LUCID Encrypted Mempool (accessed Oct 13, 2026)
- CryptoSlate: Ethereum Wants to Hide Your Trades From Bots Before They Can Attack (Aug 18, 2026)
- ethereum.org: Hegotá Roadmap (accessed Oct 13, 2026)