Decodes Base64 data into octects
/* 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.
*/
import java.io.UnsupportedEncodingException;
/**
* This class provides encode/decode for RFC 2045 Base64 as
* defined by RFC 2045, N. Freed and N. Borenstein.
* RFC 2045: Multipurpose Internet Mail Extensions (MIME)
* Part One: Format of Internet Message Bodies. Reference
* 1996 Available at: http://www.ietf.org/rfc/rfc2045.txt
* This class is used by XML Schema binary format validation
*
* This implementation does not encode/decode streaming
* data. You need the data that you will encode/decode
* already on a byte arrray.
*
*
* From xmlbeans
* @author Jeffrey Rodriguez
* @author Sandy Gao
* @version $Id: Base64.java 111285 2004-12-08 16:54:26Z cezar $
*/
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 final boolean fDebug = false;
static private byte [] base64Alphabet = new byte[BASELENGTH];
static private byte [] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];
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) '/';
}
protected static boolean isWhiteSpace(byte octect) {
return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
}
protected static boolean isPad(byte octect) {
return (octect == PAD);
}
protected static boolean isData(byte octect) {
return (base64Alphabet[octect] != -1);
}
protected static boolean isBase64(byte octect) {
return (isWhiteSpace(octect) || isPad(octect) || isData(octect));
}
/**
* Encodes hex octects into Base64
*
* @param binaryData Array containing binaryData
* @return Encoded Base64 array
*/
public static byte[] encode(byte[] binaryData) {
if (binaryData == null)
return null;
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;
if (fDebug) {
System.out.println("number of triplets = " + numberTriplets );
}
for (i = 0; i<numberTriplets; i++) {
dataIndex = i*3;
b1 = binaryData[dataIndex];
b2 = binaryData[dataIndex + 1];
b3 = binaryData[dataIndex + 2];
if (fDebug) {
System.out.println( "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 ];
if (fDebug) {
System.out.println( "val2 = " + val2 );
System.out.println( "k4 = " + (k<<4));
System.out.println( "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 );
if (fDebug) {
System.out.println("b1=" + b1);
System.out.println("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;
}
/**
* Decodes Base64 data into octects
*
* @param base64Data Byte array containing Base64 data
* @return Array containind decoded data.
*/
public static byte[] decode(byte[] base64Data) {
if (base64Data == null)
return null;
// remove white spaces
base64Data = removeWhiteSpace(base64Data);
if (base64Data.length%FOURBYTE != 0) {
return null;//should be divisible by four
}
int numberQuadruple = (base64Data.length/FOURBYTE );
if (numberQuadruple == 0)
return new byte[0];
byte decodedData[] = null;
byte b1=0,b2=0,b3=0, b4=0;//, marker0=0, marker1=0;
byte d1=0,d2=0,d3=0,d4=0;
// Throw away anything not in normalizedBase64Data
// Adjust size
int i = 0;
int encodedIndex = 0;
int dataIndex = 0;
decodedData = new byte[ (numberQuadruple)*3];
for (; i<numberQuadruple-1; i++) {
if (!isData( (d1 = base64Data[dataIndex++]) )||
!isData( (d2 = base64Data[dataIndex++]) )||
!isData( (d3 = base64Data[dataIndex++]) )||
!isData( (d4 = base64Data[dataIndex++]) ))
return null;//if found "no data" just return null
b1 = base64Alphabet[d1];
b2 = base64Alphabet[d2];
b3 = base64Alphabet[d3];
b4 = base64Alphabet[d4];
decodedData[encodedIndex++] = (byte)( b1 <<2 | b2>>4 ) ;
decodedData[encodedIndex++] = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
decodedData[encodedIndex++] = (byte)( b3<<6 | b4 );
}
if (!isData( (d1 = base64Data[dataIndex++]) ) ||
!isData( (d2 = base64Data[dataIndex++]) )) {
return null;//if found "no data" just return null
}
b1 = base64Alphabet[d1];
b2 = base64Alphabet[d2];
d3 = base64Data[dataIndex++];
d4 = base64Data[dataIndex++];
if (!isData( (d3 ) ) ||
!isData( (d4 ) )) {//Check if they are PAD characters
if (isPad( d3 ) && isPad( d4)) { //Two PAD e.g. 3c[Pad][Pad]
if ((b2 & 0xf) != 0)//last 4 bits should be zero
return null;
byte[] tmp = new byte[ i*3 + 1 ];
System.arraycopy( decodedData, 0, tmp, 0, i*3 );
tmp[encodedIndex] = (byte)( b1 <<2 | b2>>4 ) ;
return tmp;
} else if (!isPad( d3) && isPad(d4)) { //One PAD e.g. 3cQ[Pad]
b3 = base64Alphabet[ d3 ];
if ((b3 & 0x3 ) != 0)//last 2 bits should be zero
return null;
byte[] tmp = new byte[ i*3 + 2 ];
System.arraycopy( decodedData, 0, tmp, 0, i*3 );
tmp[encodedIndex++] = (byte)( b1 <<2 | b2>>4 );
tmp[encodedIndex] = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
return tmp;
} else {
return null;//an error like "3c[Pad]r", "3cdX", "3cXd", "3cXX" where X is non data
}
} else { //No PAD e.g 3cQl
b3 = base64Alphabet[ d3 ];
b4 = base64Alphabet[ d4 ];
decodedData[encodedIndex++] = (byte)( b1 <<2 | b2>>4 ) ;
decodedData[encodedIndex++] = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
decodedData[encodedIndex++] = (byte)( b3<<6 | b4 );
}
return decodedData;
}
// /**
// * Decodes Base64 data into octects
// *
// * @param base64Data String containing Base64 data
// * @return string containing decoded data.
// */
// public static String decode(String base64Data) {
// if (base64Data == null)
// return null;
//
// byte[] decoded = null;
// try {
// decoded = decode(base64Data.getBytes("utf-8"));
// }
// catch(UnsupportedEncodingException e) {
// }
// finally {
// return decoded == null ? null : new String(decoded);
// }
// }
//
// /**
// * Encodes octects (using utf-8) into Base64 data
// *
// * @param binaryData String containing Hex data
// * @return string containing decoded data.
// */
// public static String encode(String binaryData) {
// if (binaryData == null)
// return null;
//
// byte[] encoded = null;
// try {
// encoded = encode(binaryData.getBytes("utf-8"));
// }
// catch(UnsupportedEncodingException e) {}
// finally {
// return encoded == null ? null : new String(encoded);
// }
// }
/**
* remove WhiteSpace from MIME containing encoded Base64 data.
*
* @param data the byte array of base64 data (with WS)
* @return the byte array of base64 data (without WS)
*/
protected static byte[] removeWhiteSpace(byte[] data) {
if (data == null)
return null;
// count characters that's not whitespace
int newSize = 0;
int len = data.length;
for (int i = 0; i < len; i++) {
if (!isWhiteSpace(data[i]))
newSize++;
}
// if no whitespace, just return the input array
if (newSize == len)
return data;
// create the array to return
byte[] newArray = new byte[newSize];
int j = 0;
for (int i = 0; i < len; i++) {
if (!isWhiteSpace(data[i]))
newArray[j++] = data[i];
}
return newArray;
}
}
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