/*
* Copyright 2016 Red Hat, Inc. and/or its affiliates
* and other contributors as indicated by the @author tags.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.keycloak.jose.jws.crypto;
import org.keycloak.common.util.Base64Url;
import org.keycloak.jose.jws.Algorithm;
import java.security.MessageDigest;
import java.util.Arrays;
/**
* @author <a href="mailto:mposolda@redhat.com">Marek Posolda</a>
*/
public class HashProvider {
// See "at_hash" and "c_hash" in OIDC specification
public static String oidcHash(Algorithm jwtAlgorithm, String input) {
byte[] digest = digest(jwtAlgorithm, input);
int hashLength = digest.length / 2;
byte[] hashInput = Arrays.copyOf(digest, hashLength);
return Base64Url.encode(hashInput);
}
private static byte[] digest(Algorithm algorithm, String input) {
String digestAlg = getJavaDigestAlgorithm(algorithm);
try {
MessageDigest md = MessageDigest.getInstance(digestAlg);
md.update(input.getBytes("UTF-8"));
return md.digest();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private static String getJavaDigestAlgorithm(Algorithm alg) {
switch (alg) {
case RS256:
return "SHA-256";
case RS384:
return "SHA-384";
case RS512:
return "SHA-512";
default:
throw new IllegalArgumentException("Not an RSA Algorithm");
}
}
}