/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 an MD5 digest into a String.
* <p>
* The 128 bit MD5 hash is converted into a 32 character long String.
* Each character of the String is the hexadecimal representation of 4 bits
* of the digest.
*
* @author Remy Maucherat
*
*/
public final class MD5Encoder {
// ----------------------------------------------------- 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 128 bit (16 bytes) MD5 into a 32 character String.
*
* @param binaryData Array containing the digest
* @return Encoded MD5, or null if encoding failed
*/
public String encode( byte[] binaryData ) {
if (binaryData.length != 16)
return null;
char[] buffer = new char[32];
for (int i=0; i<16; 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 new String(buffer);
}
}