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; } }