Glossary

JCS canonical JSON — definition and why receipts use it

**JCS** (JSON Canonicalization Scheme) is defined in RFC 8785. It produces a deterministic byte representation of any JSON value, enabling cryptographic signatures over JSON that are reproducibly verifiable across implementations.
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Rules

Sort keys lexicographically; minimal escaping in strings; numbers in shortest form; no insignificant whitespace.

Why it matters

Standard JSON allows arbitrary key ordering, whitespace, number formatting. Two parsers can serialise the same logical content to different bytes — a signature over one serialisation won't verify over the other. JCS makes signatures reproducible.

Use in work receipts

Receipts are JCS-canonicalised before Ed25519 signing. The verifier re-canonicalises the receipt content (minus signature) and verifies against the signature.

Implementations

TypeScript: canonicalize npm package. Python: jcs PyPI package. Spec repo includes test vectors.

Related

Ed25519

Elliptic-curve digital signature scheme (RFC 8032). Short signatures, fast verification, strong security.

work receipt

A signed JSON record of AI-mediated work. Ed25519 signature over JCS-canonical JSON.

agent DID

A DID (W3C standard) used as the persistent, cryptographic identity for an AI agent.

SHA-512

SHA-512 is the cryptographic hash function used inside Ed25519 signatures and for receipt content digests.

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Last reviewed · 2 min read· Open spec· Changelog