`alg-map`

Purpose

Bridge between IANA COSE Algorithm identifiers (CoseAlg literal strings or the equivalent numeric labels from RFC 9053 §2) and the suaveplan-internal algorithm identifiers consumed by @suaveplan/crypto-curve, @suaveplan/crypto-cipher, and @suaveplan/crypto-hash. The bridge is the single point where COSE / CWT / WebAuthn flows decide which suaveplan primitive will run for a given algorithm label.

Features

Full IANA registry coverage for the algorithms the crypto packages ship: ES256, ES384, ES512, EdDSA (Ed25519), RS256, RS384, RS512, HS256, HS384, HS512, A128GCM, A192GCM, A256GCM, ChaCha20Poly1305.
Accepts both the typed CoseAlg string and the raw IANA numeric label.
Reverse mapping (cryptoAlgToCoseAlg) for outbound encoding.
Throws CborError(UNEXPECTED_TYPE) for any algorithm the bridge does not implement — this is the intentional point of failure when a caller tries to use a primitive suaveplan does not (yet) ship.

Usage: Basic Example

import { coseAlgToCryptoAlg } from "@suaveplan/cbor/cose";

const alg = coseAlgToCryptoAlg("ES256"); // "ecdsa-p256-sha256"

Usage: Advanced Example

import { coseAlgToCryptoAlg, decodeCoseKey } from "@suaveplan/cbor/cose";

// CWT verification dispatch
const key = decodeCoseKey(keyBytes);
const cryptoAlg = coseAlgToCryptoAlg(key.alg ?? "ES256");
switch (cryptoAlg) {
  case "ecdsa-p256-sha256":
    // hand off to @suaveplan/crypto-curve.p256.verify
    break;
  case "ed25519":
    // hand off to @suaveplan/crypto-curve.ed25519.verify
    break;
  // ...
}

API Reference

coseAlgToCryptoAlg(alg: CoseAlg | number): suaveplanCryptoAlg
cryptoAlgToCoseAlg(alg: suaveplanCryptoAlg): CoseAlg
type suaveplanCryptoAlg — literal-typed union of the suaveplan-internal algorithm IDs the bridge resolves to.

Throws CborError(UNEXPECTED_TYPE) for unknown numeric labels and for algorithm strings outside the supported set.

Implementation Notes

The bridge is a static lookup table — adding a new algorithm requires a single new entry in both the CoseAlg literal type and the ALG_BRIDGE record, plus a corresponding entry in the IANA-driven COSE_ALG_LABELS. Keeping the conversion in a separate module (rather than threading raw strings through the codec) ensures every inbound algorithm label crosses exactly one validation boundary before reaching the cryptographic core.

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alg-map