appserver/web/web-core/src/main/java/org/apache/catalina/util/DigestEncoderBase.java

/*
 * Copyright (c) 1997-2018 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * 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.apache.catalina.util;


/**
 * Encode a digest into a String.
 * <p>
 * The digest hash is converted into a character long String.
 * Each character of the String is the hexadecimal representation of 4 bits
 * of the digest.
 *
 * @author Remy Maucherat
 * @version $Revision: 1.2 $ $Date: 2005/12/08 01:28:18 $
 */

class DigestEncoderBase {

    // ----------------------------------------------------- Instance Variables


    private static final char[] hexadecimal =
    {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
     'a', 'b', 'c', 'd', 'e', 'f'};


    // --------------------------------------------------------- Public Methods


    /**
     * Encodes the 8m bit (m bytes) MD5 into a 2m character String.
     *
     * @param binaryData Array containing the digest
     * @return Encoded digest, or null if encoding failed
     */
    public char[] encode( byte[] binaryData ) {

        char[] buffer = new char[2 * binaryData.length];

        for (int i=0; i < binaryData.length; i++) {
            int low = (int) (binaryData[i] & 0x0f);
            int high = (int) ((binaryData[i] & 0xf0) >> 4);
            buffer[i*2] = hexadecimal[high];
            buffer[i*2 + 1] = hexadecimal[low];
        }

        return buffer;
    }
}