content: /*
   * Copyright (C) 2010 The MobileSecurePay Project
   * All right reserved.
   * author: shiqun.shi@alipay.com
   */
  
  package me.flyray.common.utils;
  
  public final class Base64 {
  
      static private final int     BASELENGTH           = 128;
      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     FOURBYTE             = 4;
      static private final int     SIGN                 = -128;
      static private final char    PAD                  = '=';
      static private final boolean fDebug               = false;
      static final private byte[]  base64Alphabet       = new byte[BASELENGTH];
      static final private char[]  lookUpBase64Alphabet = new char[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] = (char) ('A' + i);
          }
  
          for (int i = 26, j = 0; i <= 51; i++, j++) {
              lookUpBase64Alphabet[i] = (char) ('a' + j);
          }
  
          for (int i = 52, j = 0; i <= 61; i++, j++) {
              lookUpBase64Alphabet[i] = (char) ('0' + j);
          }
          lookUpBase64Alphabet[62] = (char) '+';
          lookUpBase64Alphabet[63] = (char) '/';
  
      }
  
      private static boolean isWhiteSpace(char octect) {
          return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
      }
  
      private static boolean isPad(char octect) {
          return (octect == PAD);
      }
  
      private static boolean isData(char octect) {
          return (octect < BASELENGTH && base64Alphabet[octect] != -1);
      }
  
      /**
       * Encodes hex octects into Base64
       *
       * @param binaryData Array containing binaryData
       * @return Encoded Base64 array
       */
      public static String encode(byte[] binaryData) {
  
          if (binaryData == null) {
              return null;
          }
  
          int lengthDataBits = binaryData.length * EIGHTBIT;
          if (lengthDataBits == 0) {
              return "";
          }
  
          int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
          int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
          int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
          char encodedData[] = null;
  
          encodedData = new char[numberQuartet * 4];
  
          byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
  
          int encodedIndex = 0;
          int dataIndex = 0;
          if (fDebug) {
              System.out.println("number of triplets = " + numberTriplets);
          }
  
          for (int i = 0; i < numberTriplets; i++) {
              b1 = binaryData[dataIndex++];
              b2 = binaryData[dataIndex++];
              b3 = binaryData[dataIndex++];
  
              if (fDebug) {
                  System.out.println("b1= " + b1 + ", b2= " + b2 + ", b3= " + b3);
              }
  
              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);
              byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
  
              if (fDebug) {
                  System.out.println("val2 = " + val2);
                  System.out.println("k4   = " + (k << 4));
                  System.out.println("vak  = " + (val2 | (k << 4)));
              }
  
              encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
              encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
              encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
              encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
          }
  
          // form integral number of 6-bit groups
          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++] = lookUpBase64Alphabet[k << 4];
              encodedData[encodedIndex++] = PAD;
              encodedData[encodedIndex++] = 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++] = lookUpBase64Alphabet[val2 | (k << 4)];
              encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
              encodedData[encodedIndex++] = PAD;
          }
  
          return new String(encodedData);
      }
  
      /**
       * Decodes Base64 data into octects
       *
       * @param encoded string containing Base64 data
       * @return Array containind decoded data.
       */
      public static byte[] decode(String encoded) {
  
          if (encoded == null) {
              return null;
          }
  
          char[] base64Data = encoded.toCharArray();
          // remove white spaces
          int len = removeWhiteSpace(base64Data);
  
          if (len % FOURBYTE != 0) {
              return null;//should be divisible by four
          }
  
          int numberQuadruple = (len / FOURBYTE);
  
          if (numberQuadruple == 0) {
              return new byte[0];
          }
  
          byte decodedData[] = null;
          byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
          char d1 = 0, d2 = 0, d3 = 0, d4 = 0;
  
          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)) {
                  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)) {
                  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;
              }
          } 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;
      }
  
      /**
       * remove WhiteSpace from MIME containing encoded Base64 data.
       *
       * @param data  the byte array of base64 data (with WS)
       * @return      the new length
       */
      private static int removeWhiteSpace(char[] data) {
          if (data == null) {
              return 0;
          }
  
          // count characters that's not whitespace
          int newSize = 0;
          int len = data.length;
          for (int i = 0; i < len; i++) {
              if (!isWhiteSpace(data[i])) {
                  data[newSize++] = data[i];
              }
          }
          return newSize;
      }
  }
  