Signing JWT with RS512

[coylums]

Hello, I'm working with Jose and trying to sign a JWT with RS512, a requirement from an API I'm using. When I attempt to include the RS512 algorithm I get type 'RSASigner' is not a subtype of type 'Mac' with the Create a JWS example. I don't know if this is an issue with the package or how I'm trying to use RS512. Thank you.

[joaoritter]

+1 for RSA256.

[mdevalk]

Hi @coylums, any news on this? Did you get it resolved?

[ljbdelacruz]

hi any news on this? still having issues with JWT :( same error

[rbellens]

You'll first need a key to do the signing. Depending on the application, you'll need to use a key that is provided to you or you can generate one for example with the following openssl command:

ssh-keygen -t rsa -b 4096 -m PEM -f jwtRS512.key

Next, you'll need to parse the key and transform it to a JsonWebKey object. Depending on the format the key is stored in, you'll need to use the appropriate library. For example, for keys stored in pem format, you can use the package x509.

Finally, you can use this JsonWebKey for signing a jwt.

See example7 in the examples file for a full example.

jose/example/jose_example.dart

Lines 264 to 317 in 6b3eb03

	// create a JWT, sign with RS512
	void example7() async {
	var claims = JsonWebTokenClaims.fromJson({
	'exp': Duration(hours: 4).inSeconds,
	'iss': 'alice',
	});
	// create a builder, decoding the JWT in a JWS, so using a
	// JsonWebSignatureBuilder
	var builder = JsonWebSignatureBuilder();
	// set the content
	builder.jsonContent = claims.toJson();
	// add a key to sign, can only add one for JWT
	var key = _readPrivateKeyFromFile('example/jwtRS512.key');
	builder.addRecipient(key, algorithm: 'RS512');
	// build the jws
	var jws = builder.build();
	// output the compact serialization
	print('jwt compact serialization: ${jws.toCompactSerialization()}');
	}
	JsonWebKey _readPrivateKeyFromFile(String path) {
	var v = parsePem(File(path).readAsStringSync()).first;
	var keyPair = (v is PrivateKeyInfo) ? v.keyPair : v as KeyPair;
	var pKey = keyPair.privateKey as RsaPrivateKey;
	print(pKey);
	String _bytesToBase64(List<int> bytes) {
	return base64Url.encode(bytes).replaceAll('=', '');
	}
	String _intToBase64(BigInt v) {
	return _bytesToBase64(v
	.toRadixString(16)
	.replaceAllMapped(RegExp('[0-9a-f]{2}'), (m) => '${m.group(0)},')
	.split(',')
	.where((v) => v.isNotEmpty)
	.map((v) => int.parse(v, radix: 16))
	.toList());
	}
	return JsonWebKey.fromJson({
	'kty': 'RSA',
	'n': _intToBase64(pKey.modulus),
	'd': _intToBase64(pKey.privateExponent),
	'p': _intToBase64(pKey.firstPrimeFactor),
	'q': _intToBase64(pKey.secondPrimeFactor),
	'alg': 'RS512',
	'kid': 'some_id'
	});