@grizzlycbg/asset-signer

The isomorphic signing core of the Grizzly platform. It defines the signature wire format, the crypto-agile provider interface, and the AssetSigner that both signs and verifies a signed asset. It runs unchanged in Node, a browser, or a worker — its only dependency is @noble/hashes, and it imports no node: builtins.

Most applications do not use this package directly. Reach for:

• @grizzlycbg/asset-verify — to verify signed assets offline (the common case).
• @grizzlycbg/grizzly-sdk — to encrypt/decrypt/sign against a Grizzly backend.

Use @grizzlycbg/asset-signer directly only when you are building signing or verification logic and need the primitives themselves.

Why it exists

A Grizzly asset is signed with a short-lived Intermediate Signing Key (ISK) that chains to a KeyRing's Root Signing Key (RRSK) via an embedded certificate. Given the ring's public keyset, anyone can verify the chain — asset signature → intermediate cert → ring root — with no access to the Grizzly backend and no private keys.

Signing and verification live in the same package on purpose: the to-be-signed bytes are produced by one function (assetTbs) shared by both paths. Splitting them across packages is how a verifier drifts from a signer and starts accepting what it should reject — the exact failure class this package is built to prevent.

What's inside

| Export | Purpose | |---|---| | AssetSigner | Signs an asset with an ISK (sign) and verifies a SignedAsset against a ring keyset (verify). verify never throws — it returns { success, message }. | | SignatureProvider, SignatureRegistry | The crypto-agile seam. One provider per component algorithm; a registry composes them into a hybrid suite. | | SignedAsset, IntermediateCert, SigningKeysetEntry, … | The signature wire types, kept dependency-free (raw base64url strings) so a cert verifies offline. | | canonical, signingKeyFingerprint | Deterministic canonical-JSON encoding and the content-addressed id for a signing keyset. Shared by every party so ids never drift. | | SigningPausedError, AsymUnavailableError, SigningRequiredError + guards | Typed signing errors with a wire-code discriminant, so clients can branch on an encrypt failure across serialization boundaries. |

Crypto agility

AssetSigner never hardcodes an algorithm — it holds a SignatureRegistry of one SignatureProvider per component. The default suite is hybrid:ed25519+ml-dsa-65, where every component must verify (AND-verify), so the signature survives a classical or a post-quantum break.

The providers themselves live in sibling packages so this one stays free of native and PQC code:

• @grizzlycbg/pqc-native — Node/OpenSSL providers (server-side throughput).
• @grizzlycbg/pqc-noble — pure-JS providers (browser / offline verifiers).

A signature produced under one backend verifies under the other — they are byte-for-byte compatible.

Browser safety (a maintained invariant)

This package must remain bundleable for the browser. Two rules keep it that way:

1. Never import a node: builtin — or anything that transitively does, notably @grizzlycbg/core, whose barrel pulls in node:crypto/node:stream.
2. Never export a Node-only provider from the barrel. The build is CommonJS, so a top-level require cannot be tree-shaken away — one such export re-breaks every browser consumer. The node:crypto ed25519 provider deliberately lives in @grizzlycbg/pqc-native, not here.

License

ISC © Cyber Bear Group