Module keccak256 

Keccak256 precompile for the Miden VM.

This module provides both execution-time and verification-time support for Keccak256 hashing.

Architecture

Event Handler (Execution-Time)

When the VM emits a Keccak event requesting non-deterministic hash results, the processor calls KeccakPrecompile which reads input data from memory, computes the hash, provides the digest via the advice stack, and logs the raw preimage bytes as a precompile request.

Precompile Verifier (Verification-Time)

During verification, the [PrecompileVerifier] receives the stored preimage bytes, recomputes the hash, and generates a commitment P2(P2(input) || P2(digest)), where P2 stands for Poseidon2, that validates the computation was performed correctly.

Commitment Tag Format

Each request is tagged as [event_id, len_bytes, 0, 0]. The len_bytes field prevents collisions: since bytes are packed into 32-bit limbs, we must distinguish actual data bytes from padding in the final limb.

Digest Representation

A Keccak256 digest (256 bits) is represented as 8 field elements [h0, ..., h7], each containing a u32 value where hi = u32::from_le_bytes([b_{4i}, ..., b_{4i+3}]).

Structs

KeccakFeltDigest

Keccak256 digest representation in the Miden VM.

KeccakPrecompile

KeccakPreimage

Keccak256 preimage structure representing the raw input data to be hashed.

Constants

KECCAK_HASH_BYTES_EVENT_NAME

Event name for the keccak256 hash_bytes operation.