External Entity: Account State Attestation

[hendrikhofstadt]

To allow external chains to use and verify state data from Solana such as DEX prices, balances (TVL) and other information, there needs to be an attestation mechanism.

Wormhole EE-VAAs (#147) allow for new message types to be implemented. This proposal introduces a message type that attests on-chain state for Solana, more specifically it approves that at a certain slot S the data in an account A had the sha-256 hash H.

uint64 slot
[32]byte account
[32]byte hash

In order to make attestations trustworthy despite them being an External Entity VAA, we'll deploy a standardized emitter that will handle an instruction AttestAccountInstruction which takes any solana account, calculates its data hash using the sol_sha256 syscall and CPIs to the Wormhole contract EmitEEVAAInstruction to emit a EE-VAA event with the body as specified above.

Guardians will pick the log message up, attest the event emitted and subsequently produce a VAA containing the attester program as emitter and account and hash as data.

Due to such events being emitted regularly, the resulting VAAs will not be persisted on-chain (as per EE-VAA convention). Consumers need to actively listen to the Wormhole P2P network and propagate VAAs to where they should be consumed.

[leoluk]

Part of the v2 design 🎉

@hendrikhofstadt Please re-open if I'm mistaken - but it looks like this is superseded by the emitter design?