package com.jcdm.common.utils.sign;
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/**
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* Base64工具类
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*
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* @author jc
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*/
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public final class Base64
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{
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static private final int BASELENGTH = 128;
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static private final int LOOKUPLENGTH = 64;
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static private final int TWENTYFOURBITGROUP = 24;
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static private final int EIGHTBIT = 8;
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static private final int SIXTEENBIT = 16;
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static private final int FOURBYTE = 4;
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static private final int SIGN = -128;
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static private final char PAD = '=';
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static final private byte[] base64Alphabet = new byte[BASELENGTH];
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static final private char[] lookUpBase64Alphabet = new char[LOOKUPLENGTH];
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static
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{
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for (int i = 0; i < BASELENGTH; ++i)
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{
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base64Alphabet[i] = -1;
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}
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for (int i = 'Z'; i >= 'A'; i--)
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{
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base64Alphabet[i] = (byte) (i - 'A');
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}
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for (int i = 'z'; i >= 'a'; i--)
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{
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base64Alphabet[i] = (byte) (i - 'a' + 26);
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}
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for (int i = '9'; i >= '0'; i--)
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{
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base64Alphabet[i] = (byte) (i - '0' + 52);
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}
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base64Alphabet['+'] = 62;
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base64Alphabet['/'] = 63;
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for (int i = 0; i <= 25; i++)
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{
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lookUpBase64Alphabet[i] = (char) ('A' + i);
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}
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for (int i = 26, j = 0; i <= 51; i++, j++)
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{
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lookUpBase64Alphabet[i] = (char) ('a' + j);
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}
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for (int i = 52, j = 0; i <= 61; i++, j++)
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{
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lookUpBase64Alphabet[i] = (char) ('0' + j);
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}
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lookUpBase64Alphabet[62] = (char) '+';
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lookUpBase64Alphabet[63] = (char) '/';
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}
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private static boolean isWhiteSpace(char octect)
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{
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return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
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}
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private static boolean isPad(char octect)
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{
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return (octect == PAD);
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}
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private static boolean isData(char octect)
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{
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return (octect < BASELENGTH && base64Alphabet[octect] != -1);
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}
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/**
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* Encodes hex octects into Base64
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*
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* @param binaryData Array containing binaryData
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* @return Encoded Base64 array
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*/
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public static String encode(byte[] binaryData)
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{
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if (binaryData == null)
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{
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return null;
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}
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int lengthDataBits = binaryData.length * EIGHTBIT;
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if (lengthDataBits == 0)
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{
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return "";
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}
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int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
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int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
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int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
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char encodedData[] = null;
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encodedData = new char[numberQuartet * 4];
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byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
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int encodedIndex = 0;
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int dataIndex = 0;
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for (int i = 0; i < numberTriplets; i++)
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{
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b1 = binaryData[dataIndex++];
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b2 = binaryData[dataIndex++];
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b3 = binaryData[dataIndex++];
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l = (byte) (b2 & 0x0f);
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k = (byte) (b1 & 0x03);
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byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
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byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
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byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
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encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
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encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
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encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
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encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
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}
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// form integral number of 6-bit groups
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if (fewerThan24bits == EIGHTBIT)
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{
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b1 = binaryData[dataIndex];
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k = (byte) (b1 & 0x03);
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byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
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encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
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encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
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encodedData[encodedIndex++] = PAD;
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encodedData[encodedIndex++] = PAD;
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}
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else if (fewerThan24bits == SIXTEENBIT)
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{
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b1 = binaryData[dataIndex];
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b2 = binaryData[dataIndex + 1];
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l = (byte) (b2 & 0x0f);
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k = (byte) (b1 & 0x03);
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byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
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byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
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encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
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encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
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encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
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encodedData[encodedIndex++] = PAD;
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}
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return new String(encodedData);
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}
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/**
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* Decodes Base64 data into octects
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*
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* @param encoded string containing Base64 data
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* @return Array containind decoded data.
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*/
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public static byte[] decode(String encoded)
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{
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if (encoded == null)
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{
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return null;
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}
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char[] base64Data = encoded.toCharArray();
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// remove white spaces
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int len = removeWhiteSpace(base64Data);
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if (len % FOURBYTE != 0)
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{
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return null;// should be divisible by four
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}
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int numberQuadruple = (len / FOURBYTE);
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if (numberQuadruple == 0)
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{
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return new byte[0];
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}
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byte decodedData[] = null;
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byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
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char d1 = 0, d2 = 0, d3 = 0, d4 = 0;
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int i = 0;
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int encodedIndex = 0;
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int dataIndex = 0;
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decodedData = new byte[(numberQuadruple) * 3];
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for (; i < numberQuadruple - 1; i++)
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{
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if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))
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|| !isData((d3 = base64Data[dataIndex++])) || !isData((d4 = base64Data[dataIndex++])))
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{
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return null;
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} // if found "no data" just return null
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b1 = base64Alphabet[d1];
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b2 = base64Alphabet[d2];
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b3 = base64Alphabet[d3];
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b4 = base64Alphabet[d4];
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decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
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decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
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decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
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}
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if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++])))
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{
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return null;// if found "no data" just return null
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}
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b1 = base64Alphabet[d1];
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b2 = base64Alphabet[d2];
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d3 = base64Data[dataIndex++];
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d4 = base64Data[dataIndex++];
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if (!isData((d3)) || !isData((d4)))
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{// Check if they are PAD characters
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if (isPad(d3) && isPad(d4))
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{
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if ((b2 & 0xf) != 0)// last 4 bits should be zero
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{
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return null;
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}
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byte[] tmp = new byte[i * 3 + 1];
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System.arraycopy(decodedData, 0, tmp, 0, i * 3);
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tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
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return tmp;
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}
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else if (!isPad(d3) && isPad(d4))
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{
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b3 = base64Alphabet[d3];
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if ((b3 & 0x3) != 0)// last 2 bits should be zero
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{
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return null;
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}
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byte[] tmp = new byte[i * 3 + 2];
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System.arraycopy(decodedData, 0, tmp, 0, i * 3);
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tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
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tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
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return tmp;
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}
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else
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{
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return null;
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}
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}
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else
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{ // No PAD e.g 3cQl
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b3 = base64Alphabet[d3];
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b4 = base64Alphabet[d4];
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decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
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decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
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decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
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}
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return decodedData;
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}
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/**
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* remove WhiteSpace from MIME containing encoded Base64 data.
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*
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* @param data the byte array of base64 data (with WS)
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* @return the new length
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*/
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private static int removeWhiteSpace(char[] data)
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{
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if (data == null)
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{
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return 0;
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}
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// count characters that's not whitespace
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int newSize = 0;
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int len = data.length;
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for (int i = 0; i < len; i++)
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{
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if (!isWhiteSpace(data[i]))
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{
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data[newSize++] = data[i];
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}
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}
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return newSize;
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}
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}
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