java.security.MessageDigest.java Source code

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Here is the source code for java.security.MessageDigest.java

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/*
 * Copyright 2010 Google Inc.
 * 
 * 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 java.security;

import com.google.gwt.core.client.impl.Md5Digest;

/**
 * Message Digest algorithm - <a href=
 * "http://java.sun.com/j2se/1.4.2/docs/api/java/security/MessageDigest.html"
 * >[Sun's docs]</a>.
 */
public abstract class MessageDigest extends MessageDigestSpi {

    public static MessageDigest getInstance(String algorithm) throws NoSuchAlgorithmException {
        if ("MD5".equals(algorithm)) {
            return new Md5Digest();
        }
        throw new NoSuchAlgorithmException(algorithm + " not supported");
    }

    public static boolean isEqual(byte[] digestA, byte[] digestB) {
        int n = digestA.length;
        if (n != digestB.length) {
            return false;
        }
        for (int i = 0; i < n; ++i) {
            if (digestA[i] != digestB[i]) {
                return false;
            }
        }
        return true;
    }

    private final String algorithm;

    protected MessageDigest(String algorithm) {
        this.algorithm = algorithm;
    }

    public byte[] digest() {
        return engineDigest();
    }

    public byte[] digest(byte[] input) {
        update(input);
        return digest();
    }

    public int digest(byte[] buf, int offset, int len) throws DigestException {
        return engineDigest(buf, offset, len);
    }

    public final String getAlgorithm() {
        return algorithm;
    }

    public final int getDigestLength() {
        return engineGetDigestLength();
    }

    public void reset() {
        engineReset();
    }

    public void update(byte input) {
        engineUpdate(input);
    }

    public void update(byte[] input) {
        engineUpdate(input, 0, input.length);
    }

    public void update(byte[] input, int offset, int len) {
        engineUpdate(input, offset, len);
    }
}