§5 Identity Model

A Record MUST carry content_hash (SHA-256 of Asset bytes) and pixel_hash (§4 step 8). A Record SHOULD carry at least one perceptual digest. Registered perceptual algorithms in 1.0: pdq/1.0 (256-bit, preferred) and phash-dct/64 (64-bit baseline).

Perceptual digests and embeddings are similarity signals. They MUST NOT be used for authentication, integrity, or provenance claims — those belong to the byte tier and to C2PA (§9, §12).