text: /**
   * @Created by kaicui(https://github.com/wbpmrck).
   * @Date:2013-08-18 10:47
   * @Desc: 用于sha_256加密（输入为字符串，输出为32位加密串）
   * @Change History:
   * 1、加密代码来自:http://pajhome.org.uk/crypt/md5/
   * 2、做了兼容性优化，兼容浏览器、node.js环境
   * 3、调用exp.sha256Encode即可
   --------------------------------------------
   @created：|kaicui| 2013-08-18 10:47.
   --------------------------------------------
   */
  (function(exp){
  
  
      /*
       * Configurable variables. You may need to tweak these to be compatible with
       * the server-side, but the defaults work in most cases.
       */
      var hexcase = 0;  /* hex output format. 0 - lowercase; 1 - uppercase        */
      var b64pad  = ""; /* base-64 pad character. "=" for strict RFC compliance   */
  
      /*
       * These are the functions you'll usually want to call
       * They take string arguments and return either hex or base-64 encoded strings
       */
      function hex_sha256(s)    { return rstr2hex(rstr_sha256(str2rstr_utf8(s))); }
      function b64_sha256(s)    { return rstr2b64(rstr_sha256(str2rstr_utf8(s))); }
      function any_sha256(s, e) { return rstr2any(rstr_sha256(str2rstr_utf8(s)), e); }
      function hex_hmac_sha256(k, d)
      { return rstr2hex(rstr_hmac_sha256(str2rstr_utf8(k), str2rstr_utf8(d))); }
      function b64_hmac_sha256(k, d)
      { return rstr2b64(rstr_hmac_sha256(str2rstr_utf8(k), str2rstr_utf8(d))); }
      function any_hmac_sha256(k, d, e)
      { return rstr2any(rstr_hmac_sha256(str2rstr_utf8(k), str2rstr_utf8(d)), e); }
  
      /*
       * Perform a simple self-test to see if the VM is working
       */
      function sha256_vm_test()
      {
          return hex_sha256("abc").toLowerCase() ==
              "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad";
      }
  
      /*
       * Calculate the sha256 of a raw string
       */
      function rstr_sha256(s)
      {
          return binb2rstr(binb_sha256(rstr2binb(s), s.length * 8));
      }
  
      /*
       * Calculate the HMAC-sha256 of a key and some data (raw strings)
       */
      function rstr_hmac_sha256(key, data)
      {
          var bkey = rstr2binb(key);
          if(bkey.length > 16) bkey = binb_sha256(bkey, key.length * 8);
  
          var ipad = Array(16), opad = Array(16);
          for(var i = 0; i < 16; i++)
          {
              ipad[i] = bkey[i] ^ 0x36363636;
              opad[i] = bkey[i] ^ 0x5C5C5C5C;
          }
  
          var hash = binb_sha256(ipad.concat(rstr2binb(data)), 512 + data.length * 8);
          return binb2rstr(binb_sha256(opad.concat(hash), 512 + 256));
      }
  
      /*
       * Convert a raw string to a hex string
       */
      function rstr2hex(input)
      {
          try { hexcase } catch(e) { hexcase=0; }
          var hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";
          var output = "";
          var x;
          for(var i = 0; i < input.length; i++)
          {
              x = input.charCodeAt(i);
              output += hex_tab.charAt((x >>> 4) & 0x0F)
                  +  hex_tab.charAt( x        & 0x0F);
          }
          return output;
      }
  
      /*
       * Convert a raw string to a base-64 string
       */
      function rstr2b64(input)
      {
          try { b64pad } catch(e) { b64pad=''; }
          var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
          var output = "";
          var len = input.length;
          for(var i = 0; i < len; i += 3)
          {
              var triplet = (input.charCodeAt(i) << 16)
                  | (i + 1 < len ? input.charCodeAt(i+1) << 8 : 0)
                  | (i + 2 < len ? input.charCodeAt(i+2)      : 0);
              for(var j = 0; j < 4; j++)
              {
                  if(i * 8 + j * 6 > input.length * 8) output += b64pad;
                  else output += tab.charAt((triplet >>> 6*(3-j)) & 0x3F);
              }
          }
          return output;
      }
  
      /*
       * Convert a raw string to an arbitrary string encoding
       */
      function rstr2any(input, encoding)
      {
          var divisor = encoding.length;
          var remainders = Array();
          var i, q, x, quotient;
  
          /* Convert to an array of 16-bit big-endian values, forming the dividend */
          var dividend = Array(Math.ceil(input.length / 2));
          for(i = 0; i < dividend.length; i++)
          {
              dividend[i] = (input.charCodeAt(i * 2) << 8) | input.charCodeAt(i * 2 + 1);
          }
  
          /*
           * Repeatedly perform a long division. The binary array forms the dividend,
           * the length of the encoding is the divisor. Once computed, the quotient
           * forms the dividend for the next step. We stop when the dividend is zero.
           * All remainders are stored for later use.
           */
          while(dividend.length > 0)
          {
              quotient = Array();
              x = 0;
              for(i = 0; i < dividend.length; i++)
              {
                  x = (x << 16) + dividend[i];
                  q = Math.floor(x / divisor);
                  x -= q * divisor;
                  if(quotient.length > 0 || q > 0)
                      quotient[quotient.length] = q;
              }
              remainders[remainders.length] = x;
              dividend = quotient;
          }
  
          /* Convert the remainders to the output string */
          var output = "";
          for(i = remainders.length - 1; i >= 0; i--)
              output += encoding.charAt(remainders[i]);
  
          /* Append leading zero equivalents */
          var full_length = Math.ceil(input.length * 8 /
              (Math.log(encoding.length) / Math.log(2)))
          for(i = output.length; i < full_length; i++)
              output = encoding[0] + output;
  
          return output;
      }
  
      /*
       * Encode a string as utf-8.
       * For efficiency, this assumes the input is valid utf-16.
       */
      function str2rstr_utf8(input)
      {
          var output = "";
          var i = -1;
          var x, y;
  
          while(++i < input.length)
          {
              /* Decode utf-16 surrogate pairs */
              x = input.charCodeAt(i);
              y = i + 1 < input.length ? input.charCodeAt(i + 1) : 0;
              if(0xD800 <= x && x <= 0xDBFF && 0xDC00 <= y && y <= 0xDFFF)
              {
                  x = 0x10000 + ((x & 0x03FF) << 10) + (y & 0x03FF);
                  i++;
              }
  
              /* Encode output as utf-8 */
              if(x <= 0x7F)
                  output += String.fromCharCode(x);
              else if(x <= 0x7FF)
                  output += String.fromCharCode(0xC0 | ((x >>> 6 ) & 0x1F),
                      0x80 | ( x         & 0x3F));
              else if(x <= 0xFFFF)
                  output += String.fromCharCode(0xE0 | ((x >>> 12) & 0x0F),
                      0x80 | ((x >>> 6 ) & 0x3F),
                      0x80 | ( x         & 0x3F));
              else if(x <= 0x1FFFFF)
                  output += String.fromCharCode(0xF0 | ((x >>> 18) & 0x07),
                      0x80 | ((x >>> 12) & 0x3F),
                      0x80 | ((x >>> 6 ) & 0x3F),
                      0x80 | ( x         & 0x3F));
          }
          return output;
      }
  
      /*
       * Encode a string as utf-16
       */
      function str2rstr_utf16le(input)
      {
          var output = "";
          for(var i = 0; i < input.length; i++)
              output += String.fromCharCode( input.charCodeAt(i)        & 0xFF,
                  (input.charCodeAt(i) >>> 8) & 0xFF);
          return output;
      }
  
      function str2rstr_utf16be(input)
      {
          var output = "";
          for(var i = 0; i < input.length; i++)
              output += String.fromCharCode((input.charCodeAt(i) >>> 8) & 0xFF,
                  input.charCodeAt(i)        & 0xFF);
          return output;
      }
  
      /*
       * Convert a raw string to an array of big-endian words
       * Characters >255 have their high-byte silently ignored.
       */
      function rstr2binb(input)
      {
          var output = Array(input.length >> 2);
          for(var i = 0; i < output.length; i++)
              output[i] = 0;
          for(var i = 0; i < input.length * 8; i += 8)
              output[i>>5] |= (input.charCodeAt(i / 8) & 0xFF) << (24 - i % 32);
          return output;
      }
  
      /*
       * Convert an array of big-endian words to a string
       */
      function binb2rstr(input)
      {
          var output = "";
          for(var i = 0; i < input.length * 32; i += 8)
              output += String.fromCharCode((input[i>>5] >>> (24 - i % 32)) & 0xFF);
          return output;
      }
  
      /*
       * Main sha256 function, with its support functions
       */
      function sha256_S (X, n) {return ( X >>> n ) | (X << (32 - n));}
      function sha256_R (X, n) {return ( X >>> n );}
      function sha256_Ch(x, y, z) {return ((x & y) ^ ((~x) & z));}
      function sha256_Maj(x, y, z) {return ((x & y) ^ (x & z) ^ (y & z));}
      function sha256_Sigma0256(x) {return (sha256_S(x, 2) ^ sha256_S(x, 13) ^ sha256_S(x, 22));}
      function sha256_Sigma1256(x) {return (sha256_S(x, 6) ^ sha256_S(x, 11) ^ sha256_S(x, 25));}
      function sha256_Gamma0256(x) {return (sha256_S(x, 7) ^ sha256_S(x, 18) ^ sha256_R(x, 3));}
      function sha256_Gamma1256(x) {return (sha256_S(x, 17) ^ sha256_S(x, 19) ^ sha256_R(x, 10));}
      function sha256_Sigma0512(x) {return (sha256_S(x, 28) ^ sha256_S(x, 34) ^ sha256_S(x, 39));}
      function sha256_Sigma1512(x) {return (sha256_S(x, 14) ^ sha256_S(x, 18) ^ sha256_S(x, 41));}
      function sha256_Gamma0512(x) {return (sha256_S(x, 1)  ^ sha256_S(x, 8) ^ sha256_R(x, 7));}
      function sha256_Gamma1512(x) {return (sha256_S(x, 19) ^ sha256_S(x, 61) ^ sha256_R(x, 6));}
  
      var sha256_K = new Array
          (
              1116352408, 1899447441, -1245643825, -373957723, 961987163, 1508970993,
              -1841331548, -1424204075, -670586216, 310598401, 607225278, 1426881987,
              1925078388, -2132889090, -1680079193, -1046744716, -459576895, -272742522,
              264347078, 604807628, 770255983, 1249150122, 1555081692, 1996064986,
              -1740746414, -1473132947, -1341970488, -1084653625, -958395405, -710438585,
              113926993, 338241895, 666307205, 773529912, 1294757372, 1396182291,
              1695183700, 1986661051, -2117940946, -1838011259, -1564481375, -1474664885,
              -1035236496, -949202525, -778901479, -694614492, -200395387, 275423344,
              430227734, 506948616, 659060556, 883997877, 958139571, 1322822218,
              1537002063, 1747873779, 1955562222, 2024104815, -2067236844, -1933114872,
              -1866530822, -1538233109, -1090935817, -965641998
          );
  
      function binb_sha256(m, l)
      {
          var HASH = new Array(1779033703, -1150833019, 1013904242, -1521486534,
              1359893119, -1694144372, 528734635, 1541459225);
          var W = new Array(64);
          var a, b, c, d, e, f, g, h;
          var i, j, T1, T2;
  
          /* append padding */
          m[l >> 5] |= 0x80 << (24 - l % 32);
          m[((l + 64 >> 9) << 4) + 15] = l;
  
          for(i = 0; i < m.length; i += 16)
          {
              a = HASH[0];
              b = HASH[1];
              c = HASH[2];
              d = HASH[3];
              e = HASH[4];
              f = HASH[5];
              g = HASH[6];
              h = HASH[7];
  
              for(j = 0; j < 64; j++)
              {
                  if (j < 16) W[j] = m[j + i];
                  else W[j] = safe_add(safe_add(safe_add(sha256_Gamma1256(W[j - 2]), W[j - 7]),
                      sha256_Gamma0256(W[j - 15])), W[j - 16]);
  
                  T1 = safe_add(safe_add(safe_add(safe_add(h, sha256_Sigma1256(e)), sha256_Ch(e, f, g)),
                      sha256_K[j]), W[j]);
                  T2 = safe_add(sha256_Sigma0256(a), sha256_Maj(a, b, c));
                  h = g;
                  g = f;
                  f = e;
                  e = safe_add(d, T1);
                  d = c;
                  c = b;
                  b = a;
                  a = safe_add(T1, T2);
              }
  
              HASH[0] = safe_add(a, HASH[0]);
              HASH[1] = safe_add(b, HASH[1]);
              HASH[2] = safe_add(c, HASH[2]);
              HASH[3] = safe_add(d, HASH[3]);
              HASH[4] = safe_add(e, HASH[4]);
              HASH[5] = safe_add(f, HASH[5]);
              HASH[6] = safe_add(g, HASH[6]);
              HASH[7] = safe_add(h, HASH[7]);
          }
          return HASH;
      }
  
      function safe_add (x, y)
      {
          var lsw = (x & 0xFFFF) + (y & 0xFFFF);
          var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
          return (msw << 16) | (lsw & 0xFFFF);
      }
  
      exp.sha256Encode = hex_sha256;
  })(("function"===typeof require&&"object"===typeof exports)?exports:window);
  