@simplewebauthn/server
Version:
SimpleWebAuthn for Servers
92 lines (91 loc) • 3.31 kB
JavaScript
import { COSEKEYS, isCOSEAlg } from '../../cose.js';
import { mapCoseAlgToWebCryptoAlg } from './mapCoseAlgToWebCryptoAlg.js';
import { importKey } from './importKey.js';
import { isoBase64URL } from '../index.js';
import { mapCoseAlgToWebCryptoKeyAlgName } from './mapCoseAlgToWebCryptoKeyAlgName.js';
import { getWebCrypto } from './getWebCrypto.js';
/**
* Verify a signature using an RSA public key
*/
export async function verifyRSA(opts) {
const { cosePublicKey, signature, data, shaHashOverride } = opts;
const WebCrypto = await getWebCrypto();
const alg = cosePublicKey.get(COSEKEYS.alg);
const n = cosePublicKey.get(COSEKEYS.n);
const e = cosePublicKey.get(COSEKEYS.e);
if (!alg) {
throw new Error('Public key was missing alg (RSA)');
}
if (!isCOSEAlg(alg)) {
throw new Error(`Public key had invalid alg ${alg} (RSA)`);
}
if (!n) {
throw new Error('Public key was missing n (RSA)');
}
if (!e) {
throw new Error('Public key was missing e (RSA)');
}
const keyData = {
kty: 'RSA',
alg: '',
n: isoBase64URL.fromBuffer(n),
e: isoBase64URL.fromBuffer(e),
ext: false,
};
const keyAlgorithm = {
name: mapCoseAlgToWebCryptoKeyAlgName(alg),
hash: { name: mapCoseAlgToWebCryptoAlg(alg) },
};
const verifyAlgorithm = {
name: mapCoseAlgToWebCryptoKeyAlgName(alg),
};
if (shaHashOverride) {
keyAlgorithm.hash.name = mapCoseAlgToWebCryptoAlg(shaHashOverride);
}
if (keyAlgorithm.name === 'RSASSA-PKCS1-v1_5') {
if (keyAlgorithm.hash.name === 'SHA-256') {
keyData.alg = 'RS256';
}
else if (keyAlgorithm.hash.name === 'SHA-384') {
keyData.alg = 'RS384';
}
else if (keyAlgorithm.hash.name === 'SHA-512') {
keyData.alg = 'RS512';
}
else if (keyAlgorithm.hash.name === 'SHA-1') {
keyData.alg = 'RS1';
}
}
else if (keyAlgorithm.name === 'RSA-PSS') {
/**
* salt length. The default value is 20 but the convention is to use hLen, the length of the
* output of the hash function in bytes. A salt length of zero is permitted and will result in
* a deterministic signature value. The actual salt length used can be determined from the
* signature value.
*
* From https://www.cryptosys.net/pki/manpki/pki_rsaschemes.html
*/
let saltLength = 0;
if (keyAlgorithm.hash.name === 'SHA-256') {
keyData.alg = 'PS256';
saltLength = 32; // 256 bits => 32 bytes
}
else if (keyAlgorithm.hash.name === 'SHA-384') {
keyData.alg = 'PS384';
saltLength = 48; // 384 bits => 48 bytes
}
else if (keyAlgorithm.hash.name === 'SHA-512') {
keyData.alg = 'PS512';
saltLength = 64; // 512 bits => 64 bytes
}
verifyAlgorithm.saltLength = saltLength;
}
else {
throw new Error(`Unexpected RSA key algorithm ${alg} (${keyAlgorithm.name})`);
}
const key = await importKey({
keyData,
algorithm: keyAlgorithm,
});
return WebCrypto.subtle.verify(verifyAlgorithm, key, signature, data);
}