function unusable(name, prop = 'algorithm.name') { return new TypeError(`CryptoKey does not support this operation, its ${prop} must be ${name}`); } function isAlgorithm(algorithm, name) { return algorithm.name === name; } function getHashLength(hash) { return parseInt(hash.name.slice(4), 10); } function getNamedCurve(alg) { switch (alg) { case 'ES256': return 'P-256'; case 'ES384': return 'P-384'; case 'ES512': return 'P-521'; default: throw new Error('unreachable'); } } function checkUsage(key, usages) { if (usages.length && !usages.some((expected) => key.usages.includes(expected))) { let msg = 'CryptoKey does not support this operation, its usages must include '; if (usages.length > 2) { const last = usages.pop(); msg += `one of ${usages.join(', ')}, or ${last}.`; } else if (usages.length === 2) { msg += `one of ${usages[0]} or ${usages[1]}.`; } else { msg += `${usages[0]}.`; } throw new TypeError(msg); } } export function checkSigCryptoKey(key, alg, ...usages) { switch (alg) { case 'HS256': case 'HS384': case 'HS512': { if (!isAlgorithm(key.algorithm, 'HMAC')) throw unusable('HMAC'); const expected = parseInt(alg.slice(2), 10); const actual = getHashLength(key.algorithm.hash); if (actual !== expected) throw unusable(`SHA-${expected}`, 'algorithm.hash'); break; } case 'RS256': case 'RS384': case 'RS512': { if (!isAlgorithm(key.algorithm, 'RSASSA-PKCS1-v1_5')) throw unusable('RSASSA-PKCS1-v1_5'); const expected = parseInt(alg.slice(2), 10); const actual = getHashLength(key.algorithm.hash); if (actual !== expected) throw unusable(`SHA-${expected}`, 'algorithm.hash'); break; } case 'PS256': case 'PS384': case 'PS512': { if (!isAlgorithm(key.algorithm, 'RSA-PSS')) throw unusable('RSA-PSS'); const expected = parseInt(alg.slice(2), 10); const actual = getHashLength(key.algorithm.hash); if (actual !== expected) throw unusable(`SHA-${expected}`, 'algorithm.hash'); break; } case 'EdDSA': { if (key.algorithm.name !== 'Ed25519' && key.algorithm.name !== 'Ed448') { throw unusable('Ed25519 or Ed448'); } break; } case 'ES256': case 'ES384': case 'ES512': { if (!isAlgorithm(key.algorithm, 'ECDSA')) throw unusable('ECDSA'); const expected = getNamedCurve(alg); const actual = key.algorithm.namedCurve; if (actual !== expected) throw unusable(expected, 'algorithm.namedCurve'); break; } default: throw new TypeError('CryptoKey does not support this operation'); } checkUsage(key, usages); } export function checkEncCryptoKey(key, alg, ...usages) { switch (alg) { case 'A128GCM': case 'A192GCM': case 'A256GCM': { if (!isAlgorithm(key.algorithm, 'AES-GCM')) throw unusable('AES-GCM'); const expected = parseInt(alg.slice(1, 4), 10); const actual = key.algorithm.length; if (actual !== expected) throw unusable(expected, 'algorithm.length'); break; } case 'A128KW': case 'A192KW': case 'A256KW': { if (!isAlgorithm(key.algorithm, 'AES-KW')) throw unusable('AES-KW'); const expected = parseInt(alg.slice(1, 4), 10); const actual = key.algorithm.length; if (actual !== expected) throw unusable(expected, 'algorithm.length'); break; } case 'ECDH': { switch (key.algorithm.name) { case 'ECDH': case 'X25519': case 'X448': break; default: throw unusable('ECDH, X25519, or X448'); } break; } case 'PBES2-HS256+A128KW': case 'PBES2-HS384+A192KW': case 'PBES2-HS512+A256KW': if (!isAlgorithm(key.algorithm, 'PBKDF2')) throw unusable('PBKDF2'); break; case 'RSA-OAEP': case 'RSA-OAEP-256': case 'RSA-OAEP-384': case 'RSA-OAEP-512': { if (!isAlgorithm(key.algorithm, 'RSA-OAEP')) throw unusable('RSA-OAEP'); const expected = parseInt(alg.slice(9), 10) || 1; const actual = getHashLength(key.algorithm.hash); if (actual !== expected) throw unusable(`SHA-${expected}`, 'algorithm.hash'); break; } default: throw new TypeError('CryptoKey does not support this operation'); } checkUsage(key, usages); }