Ethereum's ERC-8424 draft would give RWA issuers forced transfers over encrypted balances

A draft Ethereum standard called ERC-8424 went up for review on Friday. Issuers of tokenized real-world assets (RWAs) would be able to force-transfer assets that still have encrypted amounts.

The pull request was published by Aryeh Greenberg, an OpenZeppelin developer who posts as arr00 in the ethereum/ERCs repository.

ERC-8424 adds two public checks and three private functions to ERC-7984

An Ethereum standard named ERC-7984 already exists for private tokens that store amounts as encrypted pointers. ERC-8424 builds on that standard.

The draft also has two plaintext eligibility checks, a confidential check to see if a certain transfer is allowed, a confidential number showing how much of a balance can be spent, and a forced transfer that only authorized parties can use.

When figuring out the amount that can be spent, issuer freezes, lockups, vesting schedules, and pledged amounts must be taken into account. The draft puts limits on minting, burning, stopping, and freezing, but it doesn’t say how they should be put into action.

There are rules about who can transfer money and how much can be sent. “An issuer may be required to move assets without a holder’s consent,” the draft also says.

In the draft, it is written that ERC-3643 and ERC-7943 for tokens with public balances already take care of these tasks.

A reviewer warns of a 64-call path to an encrypted amount held by a holder

A forum participant named zexoverz found a hole in the draft on the Ethereum Magicians thread on Friday morning.

The transfer check and the spendable-balance function don’t limit who can call them, so anyone can look into someone else’s account.

zexoverz said that a binary search can find a 64-bit encrypted balance in at most 64 calls, but only if the person calling can also decrypt the answer.

zexoverz said the spendable-balance function would reveal the balance in a single call.

zexoverz pointed out that OpenZeppelin’s current ERC7984Freezable code only lets the account holder see their own figure. He asked that the same rule be added to the spec.

Vesting and balance caps depend on the amount, so a failed transfer there leaks exactly what the draft’s “Disclosure through reverts” section warns about, without decrypting anything, zexoverz explained.

ERC-8424 is still a draft and needs one more review from an Ethereum editor, either g11tech, jochem-brouwer, samwilsn or xinbenlv.

abcoathup assigned the draft its number, 8424, on Friday and renamed the forum thread to match.

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