Encode/decode for RFC 2045 Base64 as defined by RFC 2045
/*
* 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.
*/
/**
* This class provides encode/decode for RFC 2045 Base64 as defined by
* RFC 2045, N. Freed and N. Borenstein. <a
* href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>:
* Multipurpose Internet Mail Extensions (MIME) Part One: Format of
* Internet Message Bodies. Reference 1996
*
* @author Jeffrey Rodriguez
* @version $Id: Base64.java 515 2008-03-17 21:02:23Z jfrederic.clere@jboss.com $
*/
public final class Base64
{
static private final int BASELENGTH = 255;
static private final int LOOKUPLENGTH = 64;
static private final int TWENTYFOURBITGROUP = 24;
static private final int EIGHTBIT = 8;
static private final int SIXTEENBIT = 16;
static private final int SIXBIT = 6;
static private final int FOURBYTE = 4;
static private final int SIGN = -128;
static private final byte PAD = (byte) '=';
static private byte [] base64Alphabet = new byte[BASELENGTH];
static private byte [] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];
//static private final Log log = LogSource.getInstance("org.apache.commons.util.Base64");
static
{
for (int i = 0; i < BASELENGTH; i++ )
{
base64Alphabet[i] = -1;
}
for (int i = 'Z'; i >= 'A'; i--)
{
base64Alphabet[i] = (byte) (i - 'A');
}
for (int i = 'z'; i>= 'a'; i--)
{
base64Alphabet[i] = (byte) (i - 'a' + 26);
}
for (int i = '9'; i >= '0'; i--)
{
base64Alphabet[i] = (byte) (i - '0' + 52);
}
base64Alphabet['+'] = 62;
base64Alphabet['/'] = 63;
for (int i = 0; i <= 25; i++ )
lookUpBase64Alphabet[i] = (byte) ('A' + i);
for (int i = 26, j = 0; i <= 51; i++, j++ )
lookUpBase64Alphabet[i] = (byte) ('a'+ j);
for (int i = 52, j = 0; i <= 61; i++, j++ )
lookUpBase64Alphabet[i] = (byte) ('0' + j);
lookUpBase64Alphabet[62] = (byte) '+';
lookUpBase64Alphabet[63] = (byte) '/';
}
public static boolean isBase64( String isValidString )
{
return isArrayByteBase64(isValidString.getBytes());
}
public static boolean isBase64( byte octect )
{
//shall we ignore white space? JEFF??
return (octect == PAD || base64Alphabet[octect] != -1);
}
public static boolean isArrayByteBase64( byte[] arrayOctect )
{
int length = arrayOctect.length;
if (length == 0)
{
// shouldn't a 0 length array be valid base64 data?
// return false;
return true;
}
for (int i=0; i < length; i++)
{
if ( !Base64.isBase64(arrayOctect[i]) )
return false;
}
return true;
}
/**
* Encodes hex octects into Base64.
*
* @param binaryData Array containing binary data to encode.
* @return Base64-encoded data.
*/
public static byte[] encode( byte[] binaryData )
{
int lengthDataBits = binaryData.length*EIGHTBIT;
int fewerThan24bits = lengthDataBits%TWENTYFOURBITGROUP;
int numberTriplets = lengthDataBits/TWENTYFOURBITGROUP;
byte encodedData[] = null;
if (fewerThan24bits != 0)
{
//data not divisible by 24 bit
encodedData = new byte[ (numberTriplets + 1 ) * 4 ];
}
else
{
// 16 or 8 bit
encodedData = new byte[ numberTriplets * 4 ];
}
byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
int encodedIndex = 0;
int dataIndex = 0;
int i = 0;
//log.debug("number of triplets = " + numberTriplets);
for ( i = 0; i<numberTriplets; i++ )
{
dataIndex = i*3;
b1 = binaryData[dataIndex];
b2 = binaryData[dataIndex + 1];
b3 = binaryData[dataIndex + 2];
//log.debug("b1= " + b1 +", b2= " + b2 + ", b3= " + b3);
l = (byte)(b2 & 0x0f);
k = (byte)(b1 & 0x03);
encodedIndex = i * 4;
byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
byte val2 = ((b2 & SIGN)==0)?(byte)(b2>>4):(byte)((b2)>>4^0xf0);
byte val3 = ((b3 & SIGN)==0)?(byte)(b3>>6):(byte)((b3)>>6^0xfc);
encodedData[encodedIndex] = lookUpBase64Alphabet[ val1 ];
//log.debug( "val2 = " + val2 );
//log.debug( "k4 = " + (k<<4) );
//log.debug( "vak = " + (val2 | (k<<4)) );
encodedData[encodedIndex+1] =
lookUpBase64Alphabet[ val2 | ( k<<4 )];
encodedData[encodedIndex+2] =
lookUpBase64Alphabet[ (l <<2 ) | val3 ];
encodedData[encodedIndex+3] = lookUpBase64Alphabet[ b3 & 0x3f ];
}
// form integral number of 6-bit groups
dataIndex = i*3;
encodedIndex = i*4;
if (fewerThan24bits == EIGHTBIT )
{
b1 = binaryData[dataIndex];
k = (byte) ( b1 &0x03 );
//log.debug("b1=" + b1);
//log.debug("b1<<2 = " + (b1>>2) );
byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
encodedData[encodedIndex] = lookUpBase64Alphabet[ val1 ];
encodedData[encodedIndex + 1] = lookUpBase64Alphabet[ k<<4 ];
encodedData[encodedIndex + 2] = PAD;
encodedData[encodedIndex + 3] = PAD;
}
else if (fewerThan24bits == SIXTEENBIT)
{
b1 = binaryData[dataIndex];
b2 = binaryData[dataIndex +1 ];
l = (byte) (b2 & 0x0f);
k = (byte) (b1 & 0x03);
byte val1 = ((b1 & SIGN) == 0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
byte val2 = ((b2 & SIGN) == 0)?(byte)(b2>>4):(byte)((b2)>>4^0xf0);
encodedData[encodedIndex] = lookUpBase64Alphabet[ val1 ];
encodedData[encodedIndex + 1] =
lookUpBase64Alphabet[ val2 | ( k<<4 )];
encodedData[encodedIndex + 2] = lookUpBase64Alphabet[ l<<2 ];
encodedData[encodedIndex + 3] = PAD;
}
return encodedData;
}
}