import { COSECRV, COSEKEYS } from '../../cose.js'; import { mapCoseAlgToWebCryptoAlg } from './mapCoseAlgToWebCryptoAlg.js'; import { importKey } from './importKey.js'; import { isoBase64URL } from '../index.js'; import { getWebCrypto } from './getWebCrypto.js'; /** * Verify a signature using an EC2 public key */ export async function verifyEC2(opts) { const { cosePublicKey, signature, data, shaHashOverride } = opts; const WebCrypto = await getWebCrypto(); // Import the public key const alg = cosePublicKey.get(COSEKEYS.alg); const crv = cosePublicKey.get(COSEKEYS.crv); const x = cosePublicKey.get(COSEKEYS.x); const y = cosePublicKey.get(COSEKEYS.y); if (!alg) { throw new Error('Public key was missing alg (EC2)'); } if (!crv) { throw new Error('Public key was missing crv (EC2)'); } if (!x) { throw new Error('Public key was missing x (EC2)'); } if (!y) { throw new Error('Public key was missing y (EC2)'); } let _crv; if (crv === COSECRV.P256) { _crv = 'P-256'; } else if (crv === COSECRV.P384) { _crv = 'P-384'; } else if (crv === COSECRV.P521) { _crv = 'P-521'; } else { throw new Error(`Unexpected COSE crv value of ${crv} (EC2)`); } const keyData = { kty: 'EC', crv: _crv, x: isoBase64URL.fromBuffer(x), y: isoBase64URL.fromBuffer(y), ext: false, }; const keyAlgorithm = { /** * Note to future self: you can't use `mapCoseAlgToWebCryptoKeyAlgName()` here because some * leaf certs from actual devices specified an RSA SHA value for `alg` (e.g. `-257`) which * would then map here to `'RSASSA-PKCS1-v1_5'`. We always want `'ECDSA'` here so we'll * hard-code this. */ name: 'ECDSA', namedCurve: _crv, }; const key = await importKey({ keyData, algorithm: keyAlgorithm, }); // Determine which SHA algorithm to use for signature verification let subtleAlg = mapCoseAlgToWebCryptoAlg(alg); if (shaHashOverride) { subtleAlg = mapCoseAlgToWebCryptoAlg(shaHashOverride); } const verifyAlgorithm = { name: 'ECDSA', hash: { name: subtleAlg }, }; return WebCrypto.subtle.verify(verifyAlgorithm, key, signature, data); }