org.springframework.security.jwt.crypto.sign.MacSigner.java Source code

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Here is the source code for org.springframework.security.jwt.crypto.sign.MacSigner.java

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/*
 * Copyright 2006-2011 the original author or authors.
 *
 * 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
 *
 * https://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.springframework.security.jwt.crypto.sign;

import java.security.GeneralSecurityException;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
 * @author Luke Taylor
 */
public class MacSigner implements SignerVerifier {
    private static final String DEFAULT_ALGORITHM = "HMACSHA256";

    private final String algorithm;
    private final SecretKey key;

    public MacSigner(byte[] key) {
        this(new SecretKeySpec(key, DEFAULT_ALGORITHM));
    }

    public MacSigner(String key) {
        this(new SecretKeySpec(key.getBytes(), DEFAULT_ALGORITHM));
    }

    public MacSigner(SecretKey key) {
        this(DEFAULT_ALGORITHM, key);
    }

    public MacSigner(String algorithm, SecretKey key) {
        this.key = key;
        this.algorithm = algorithm;
    }

    //   val keyLength = key.getEncoded.length * 8

    public byte[] sign(byte[] bytes) {
        try {
            Mac mac = Mac.getInstance(algorithm);
            mac.init(key);
            return mac.doFinal(bytes);
        } catch (GeneralSecurityException e) {
            throw new RuntimeException(e);
        }
    }

    public void verify(byte[] content, byte[] signature) {
        byte[] signed = sign(content);
        if (!isEqual(signed, signature)) {
            throw new InvalidSignatureException("Calculated signature did not match actual value");
        }
    }

    private boolean isEqual(byte[] b1, byte[] b2) {
        if (b1.length != b2.length) {
            return false;
        }
        int xor = 0;
        for (int i = 0; i < b1.length; i++) {
            xor |= b1[i] ^ b2[i];
        }

        return xor == 0;
    }

    public String algorithm() {
        return algorithm;
    }

    @Override
    public String toString() {
        return "MacSigner: " + algorithm;
    }
}