org.identityconnectors.common.Base64 Maven / Gradle / Ivy
/*
* ====================
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 2008-2009 Sun Microsystems, Inc. All rights reserved.
*
* The contents of this file are subject to the terms of the Common Development
* and Distribution License("CDDL") (the "License"). You may not use this file
* except in compliance with the License.
*
* You can obtain a copy of the License at
* http://IdentityConnectors.dev.java.net/legal/license.txt
* See the License for the specific language governing permissions and limitations
* under the License.
*
* When distributing the Covered Code, include this CDDL Header Notice in each file
* and include the License file at identityconnectors/legal/license.txt.
* If applicable, add the following below this CDDL Header, with the fields
* enclosed by brackets [] replaced by your own identifying information:
* "Portions Copyrighted [year] [name of copyright owner]"
* ====================
*/
package org.identityconnectors.common;
/**
* Utility package for base64 encoding and decoding.
*
* @author Will Droste
* @version $Revision $
* @since 1.0
*/
public class Base64 {
private Base64() {
}
/**
* Returns a String of base64-encoded characters to represent the specified
* data array.
*
* @param data
* The array of bytes to encode.
* @return A String containing base64-encoded characters.
*/
static public String encode(byte[] data) {
if (data == null)
return null;
char[] out = new char[((data.length + 2) / 3) * 4];
//
// 3 bytes encode to 4 chars. Output is always an even
// multiple of 4 characters.
//
for (int i = 0, index = 0; i < data.length; i += 3, index += 4) {
boolean quad = false;
boolean trip = false;
int val = (0xFF & (int) data[i]);
val <<= 8;
if ((i + 1) < data.length) {
val |= (0xFF & (int) data[i + 1]);
trip = true;
}
val <<= 8;
if ((i + 2) < data.length) {
val |= (0xFF & (int) data[i + 2]);
quad = true;
}
out[index + 3] = alphabet[(quad ? (val & 0x3F) : 64)];
val >>= 6;
out[index + 2] = alphabet[(trip ? (val & 0x3F) : 64)];
val >>= 6;
out[index + 1] = alphabet[val & 0x3F];
val >>= 6;
out[index + 0] = alphabet[val & 0x3F];
}
return new String(out);
}
/**
* Decodes a specified base64-encoded String and returns the resulting bytes.
*
* @param encdata
* A String containing base64-encoded characters.
* @return The base64-decoded array of bytes.
*/
static public byte[] decode(String encdata) {
if (encdata == null)
return null;
// convert to a char[]
char[] data = encdata.toCharArray();
// An empty string is a valid base64 encoded string.
if (data.length == 0)
return new byte[0];
// check that length is a multiple of 4
if (data.length % 4 != 0)
throw new RuntimeException("Data is not Base64 encoded.");
int len = ((data.length + 3) / 4) * 3;
if (data[data.length - 1] == '=')
--len;
if (data[data.length - 2] == '=')
--len;
byte[] out = new byte[len];
int shift = 0; // # of excess bits stored in accum
int accum = 0; // excess bits
int index = 0;
for (int ix = 0; ix < data.length; ix++) {
int value = codes[data[ix] & 0xFF]; // ignore high byte of char
if (value >= 0) { // skip over non-code
accum <<= 6; // bits shift up by 6 each time thru
shift += 6; // loop, with new bits being put in
accum |= value; // at the bottom.
if (shift >= 8) { // whenever there are 8 or more shifted in,
shift -= 8; // write them out (from the top, leaving any
out[index++] = // excess at the bottom for next iteration.
(byte) ((accum >> shift) & 0xff);
}
} else {
if (data[ix] != '=') {
throw new RuntimeException("Data is not Base64 encoded.");
}
}
}
if (index != out.length)
throw new RuntimeException("Data length mismatch.");
return out;
}
//
// code characters for values 0..63
//
static private char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
.toCharArray();
//
// lookup table for converting base64 characters to value in range 0..63
//
static private byte[] codes = new byte[256];
static {
for (int i = 0; i < 256; i++)
codes[i] = -1;
for (int i = 'A'; i <= 'Z'; i++)
codes[i] = (byte) (i - 'A');
for (int i = 'a'; i <= 'z'; i++)
codes[i] = (byte) (26 + i - 'a');
for (int i = '0'; i <= '9'; i++)
codes[i] = (byte) (52 + i - '0');
codes['+'] = 62;
codes['/'] = 63;
}
}