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JS实现3des+base64加密解密算法步骤详解

php中世界最好的语言原创: 2018-05-23 10:08:302508浏览

这次给大家带来JS实现3des+base64加密解密算法，JS实现3des+base64加密解密算法的注意事项有哪些，下面就是实战案例，一起来看一下。

1. index.html：

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>BASE64编码</title>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <script type="text/javascript" src="Base64.js"></script>
  <script type="text/javascript" src="DES3.js"></script>
</head>
<body>
<script type="text/javascript">
var str = "网址：http://www.jb51.net";
document.write("原始字符串:</br>"+str);
var base64 = BASE64.encoder(str);//返回编码后的字符
document.write("</br>BASE64后:</br>"+base64);
//alert(base64);
var unicode= BASE64.decoder(base64);//返回会解码后的字符串。
//alert(unicode);
document.write("</br>还原:</br>"+unicode);
//var str= "你好123hello";
var key = "qXSdHWfbSZaaLeHBRhLgxBiG";
//alert(decrypt_3des);
var des3en = DES3.encrypt(key,str);
document.write("</br>des3加密:</br>"+des3en);
document.write("</br>des3解密:</br>"+DES3.decrypt(key,des3en));
</script>
</body>

2. DES3.js文件：

/** 
 * DES 加密算法 
 * 
 * 该函数接受一个 8 字节字符串作为普通 DES 算法的密钥（也就是 64 位，但是算法只使用 56 位），或者接受一个 24 字节字符串作为 3DES 
 * 算法的密钥；第二个参数是要加密或解密的信息字符串；第三个布尔值参数用来说明信息是加密还是解密；接下来的可选参数 mode 如果是 0 表示 ECB 
 * 模式，1 表示 CBC 模式，默认是 ECB 模式；最后一个可选项是一个 8 字节的输入向量字符串（在 ECB 模式下不使用）。返回的密文是字符串。 
 * 
 * 参数： <br> 
 * key: 8字节字符串作为普通 DES 算法的密钥,或 24 字节字符串作为 3DES <br> 
 * message： 加密或解密的信息字符串<br> 
 * encrypt: 布尔值参数用来说明信息是加密还是解密<br> 
 * mode: 1:CBC模式，0:ECB模式(默认)<br> 
 * iv:<br> 
 * padding: 可选项, 8字节的输入向量字符串（在 ECB 模式下不使用） 
 */
//this takes the key, the message, and whether to encrypt or decrypt
function des (key, message, encrypt, mode, iv, padding) {
  if(encrypt) //如果是加密的话，首先转换编码
    message = unescape(encodeURIComponent(message));
  //declaring this locally speeds things up a bit
  var spfunction1 = new Array (0x1010400,0,0x10000,0x1010404,0x1010004,0x10404,0x4,0x10000,0x400,0x1010400,0x1010404,0x400,0x1000404,0x1010004,0x1000000,0x4,0x404,0x1000400,0x1000400,0x10400,0x10400,0x1010000,0x1010000,0x1000404,0x10004,0x1000004,0x1000004,0x10004,0,0x404,0x10404,0x1000000,0x10000,0x1010404,0x4,0x1010000,0x1010400,0x1000000,0x1000000,0x400,0x1010004,0x10000,0x10400,0x1000004,0x400,0x4,0x1000404,0x10404,0x1010404,0x10004,0x1010000,0x1000404,0x1000004,0x404,0x10404,0x1010400,0x404,0x1000400,0x1000400,0,0x10004,0x10400,0,0x1010004);
  var spfunction2 = new Array (-0x7fef7fe0,-0x7fff8000,0x8000,0x108020,0x100000,0x20,-0x7fefffe0,-0x7fff7fe0,-0x7fffffe0,-0x7fef7fe0,-0x7fef8000,-0x80000000,-0x7fff8000,0x100000,0x20,-0x7fefffe0,0x108000,0x100020,-0x7fff7fe0,0,-0x80000000,0x8000,0x108020,-0x7ff00000,0x100020,-0x7fffffe0,0,0x108000,0x8020,-0x7fef8000,-0x7ff00000,0x8020,0,0x108020,-0x7fefffe0,0x100000,-0x7fff7fe0,-0x7ff00000,-0x7fef8000,0x8000,-0x7ff00000,-0x7fff8000,0x20,-0x7fef7fe0,0x108020,0x20,0x8000,-0x80000000,0x8020,-0x7fef8000,0x100000,-0x7fffffe0,0x100020,-0x7fff7fe0,-0x7fffffe0,0x100020,0x108000,0,-0x7fff8000,0x8020,-0x80000000,-0x7fefffe0,-0x7fef7fe0,0x108000);
  var spfunction3 = new Array (0x208,0x8020200,0,0x8020008,0x8000200,0,0x20208,0x8000200,0x20008,0x8000008,0x8000008,0x20000,0x8020208,0x20008,0x8020000,0x208,0x8000000,0x8,0x8020200,0x200,0x20200,0x8020000,0x8020008,0x20208,0x8000208,0x20200,0x20000,0x8000208,0x8,0x8020208,0x200,0x8000000,0x8020200,0x8000000,0x20008,0x208,0x20000,0x8020200,0x8000200,0,0x200,0x20008,0x8020208,0x8000200,0x8000008,0x200,0,0x8020008,0x8000208,0x20000,0x8000000,0x8020208,0x8,0x20208,0x20200,0x8000008,0x8020000,0x8000208,0x208,0x8020000,0x20208,0x8,0x8020008,0x20200);
  var spfunction4 = new Array (0x802001,0x2081,0x2081,0x80,0x802080,0x800081,0x800001,0x2001,0,0x802000,0x802000,0x802081,0x81,0,0x800080,0x800001,0x1,0x2000,0x800000,0x802001,0x80,0x800000,0x2001,0x2080,0x800081,0x1,0x2080,0x800080,0x2000,0x802080,0x802081,0x81,0x800080,0x800001,0x802000,0x802081,0x81,0,0,0x802000,0x2080,0x800080,0x800081,0x1,0x802001,0x2081,0x2081,0x80,0x802081,0x81,0x1,0x2000,0x800001,0x2001,0x802080,0x800081,0x2001,0x2080,0x800000,0x802001,0x80,0x800000,0x2000,0x802080);
  var spfunction5 = new Array (0x100,0x2080100,0x2080000,0x42000100,0x80000,0x100,0x40000000,0x2080000,0x40080100,0x80000,0x2000100,0x40080100,0x42000100,0x42080000,0x80100,0x40000000,0x2000000,0x40080000,0x40080000,0,0x40000100,0x42080100,0x42080100,0x2000100,0x42080000,0x40000100,0,0x42000000,0x2080100,0x2000000,0x42000000,0x80100,0x80000,0x42000100,0x100,0x2000000,0x40000000,0x2080000,0x42000100,0x40080100,0x2000100,0x40000000,0x42080000,0x2080100,0x40080100,0x100,0x2000000,0x42080000,0x42080100,0x80100,0x42000000,0x42080100,0x2080000,0,0x40080000,0x42000000,0x80100,0x2000100,0x40000100,0x80000,0,0x40080000,0x2080100,0x40000100);
  var spfunction6 = new Array (0x20000010,0x20400000,0x4000,0x20404010,0x20400000,0x10,0x20404010,0x400000,0x20004000,0x404010,0x400000,0x20000010,0x400010,0x20004000,0x20000000,0x4010,0,0x400010,0x20004010,0x4000,0x404000,0x20004010,0x10,0x20400010,0x20400010,0,0x404010,0x20404000,0x4010,0x404000,0x20404000,0x20000000,0x20004000,0x10,0x20400010,0x404000,0x20404010,0x400000,0x4010,0x20000010,0x400000,0x20004000,0x20000000,0x4010,0x20000010,0x20404010,0x404000,0x20400000,0x404010,0x20404000,0,0x20400010,0x10,0x4000,0x20400000,0x404010,0x4000,0x400010,0x20004010,0,0x20404000,0x20000000,0x400010,0x20004010);
  var spfunction7 = new Array (0x200000,0x4200002,0x4000802,0,0x800,0x4000802,0x200802,0x4200800,0x4200802,0x200000,0,0x4000002,0x2,0x4000000,0x4200002,0x802,0x4000800,0x200802,0x200002,0x4000800,0x4000002,0x4200000,0x4200800,0x200002,0x4200000,0x800,0x802,0x4200802,0x200800,0x2,0x4000000,0x200800,0x4000000,0x200800,0x200000,0x4000802,0x4000802,0x4200002,0x4200002,0x2,0x200002,0x4000000,0x4000800,0x200000,0x4200800,0x802,0x200802,0x4200800,0x802,0x4000002,0x4200802,0x4200000,0x200800,0,0x2,0x4200802,0,0x200802,0x4200000,0x800,0x4000002,0x4000800,0x800,0x200002);
  var spfunction8 = new Array (0x10001040,0x1000,0x40000,0x10041040,0x10000000,0x10001040,0x40,0x10000000,0x40040,0x10040000,0x10041040,0x41000,0x10041000,0x41040,0x1000,0x40,0x10040000,0x10000040,0x10001000,0x1040,0x41000,0x40040,0x10040040,0x10041000,0x1040,0,0,0x10040040,0x10000040,0x10001000,0x41040,0x40000,0x41040,0x40000,0x10041000,0x1000,0x40,0x10040040,0x1000,0x41040,0x10001000,0x40,0x10000040,0x10040000,0x10040040,0x10000000,0x40000,0x10001040,0,0x10041040,0x40040,0x10000040,0x10040000,0x10001000,0x10001040,0,0x10041040,0x41000,0x41000,0x1040,0x1040,0x40040,0x10000000,0x10041000);
  //create the 16 or 48 subkeys we will need
  var keys = des_createKeys (key);
  var m=0, i, j, temp, temp2, right1, right2, left, right, looping;
  var cbcleft, cbcleft2, cbcright, cbcright2
  var endloop, loopinc;
  var len = message.length;
  var chunk = 0;
  //set up the loops for single and triple des
  var iterations = keys.length == 32 ? 3 : 9; //single or triple des
  if (iterations == 3) {looping = encrypt ? new Array (0, 32, 2) : new Array (30, -2, -2);}
  else {looping = encrypt ? new Array (0, 32, 2, 62, 30, -2, 64, 96, 2) : new Array (94, 62, -2, 32, 64, 2, 30, -2, -2);}
  //pad the message depending on the padding parameter
  if (padding == 2) message += "    "; //pad the message with spaces
  else if (padding == 1) {
    if(encrypt) {
      temp = 8-(len%8);
      message += String.fromCharCode(temp,temp,temp,temp,temp,temp,temp,temp);
      if (temp===8) len+=8;
    }
  } //PKCS7 padding
  else if (!padding) message += "\0\0\0\0\0\0\0\0"; //pad the message out with null bytes
  //store the result here
  var result = "";
  var tempresult = "";
  if (mode == 1) { //CBC mode
    cbcleft = (iv.charCodeAt(m++) << 24) | (iv.charCodeAt(m++) << 16) | (iv.charCodeAt(m++) << 8) | iv.charCodeAt(m++);
    cbcright = (iv.charCodeAt(m++) << 24) | (iv.charCodeAt(m++) << 16) | (iv.charCodeAt(m++) << 8) | iv.charCodeAt(m++);
    m=0;
  }
  //loop through each 64 bit chunk of the message
  while (m < len) {
    left = (message.charCodeAt(m++) << 24) | (message.charCodeAt(m++) << 16) | (message.charCodeAt(m++) << 8) | message.charCodeAt(m++);
    right = (message.charCodeAt(m++) << 24) | (message.charCodeAt(m++) << 16) | (message.charCodeAt(m++) << 8) | message.charCodeAt(m++);
    //for Cipher Block Chaining mode, xor the message with the previous result
    if (mode == 1) {if (encrypt) {left ^= cbcleft; right ^= cbcright;} else {cbcleft2 = cbcleft; cbcright2 = cbcright; cbcleft = left; cbcright = right;}}
    //first each 64 but chunk of the message must be permuted according to IP
    temp = ((left >>> 4) ^ right) & 0x0f0f0f0f; right ^= temp; left ^= (temp << 4);
    temp = ((left >>> 16) ^ right) & 0x0000ffff; right ^= temp; left ^= (temp << 16);
    temp = ((right >>> 2) ^ left) & 0x33333333; left ^= temp; right ^= (temp << 2);
    temp = ((right >>> 8) ^ left) & 0x00ff00ff; left ^= temp; right ^= (temp << 8);
    temp = ((left >>> 1) ^ right) & 0x55555555; right ^= temp; left ^= (temp << 1);
    left = ((left << 1) | (left >>> 31));
    right = ((right << 1) | (right >>> 31));
    //do this either 1 or 3 times for each chunk of the message
    for (j=0; j<iterations; j+=3) {
      endloop = looping[j+1];
      loopinc = looping[j+2];
      //now go through and perform the encryption or decryption
      for (i=looping[j]; i!=endloop; i+=loopinc) { //for efficiency
        right1 = right ^ keys[i];
        right2 = ((right >>> 4) | (right << 28)) ^ keys[i+1];
        //the result is attained by passing these bytes through the S selection functions
        temp = left;
        left = right;
        right = temp ^ (spfunction2[(right1 >>> 24) & 0x3f] | spfunction4[(right1 >>> 16) & 0x3f]
          | spfunction6[(right1 >>> 8) & 0x3f] | spfunction8[right1 & 0x3f]
          | spfunction1[(right2 >>> 24) & 0x3f] | spfunction3[(right2 >>> 16) & 0x3f]
          | spfunction5[(right2 >>> 8) & 0x3f] | spfunction7[right2 & 0x3f]);
      }
      temp = left; left = right; right = temp; //unreverse left and right
    } //for either 1 or 3 iterations
    //move then each one bit to the right
    left = ((left >>> 1) | (left << 31));
    right = ((right >>> 1) | (right << 31));
    //now perform IP-1, which is IP in the opposite direction
    temp = ((left >>> 1) ^ right) & 0x55555555; right ^= temp; left ^= (temp << 1);
    temp = ((right >>> 8) ^ left) & 0x00ff00ff; left ^= temp; right ^= (temp << 8);
    temp = ((right >>> 2) ^ left) & 0x33333333; left ^= temp; right ^= (temp << 2);
    temp = ((left >>> 16) ^ right) & 0x0000ffff; right ^= temp; left ^= (temp << 16);
    temp = ((left >>> 4) ^ right) & 0x0f0f0f0f; right ^= temp; left ^= (temp << 4);
    //for Cipher Block Chaining mode, xor the message with the previous result
    if (mode == 1) {if (encrypt) {cbcleft = left; cbcright = right;} else {left ^= cbcleft2; right ^= cbcright2;}}
    tempresult += String.fromCharCode ((left>>>24), ((left>>>16) & 0xff), ((left>>>8) & 0xff), (left & 0xff), (right>>>24), ((right>>>16) & 0xff), ((right>>>8) & 0xff), (right & 0xff));
    chunk += 8;
    if (chunk == 512) {result += tempresult; tempresult = ""; chunk = 0;}
  } //for every 8 characters, or 64 bits in the message
  //return the result as an array
  result += tempresult;
  result = result.replace(/\0*$/g, "");
  if(!encrypt ) { //如果是解密的话，解密结束后对PKCS7 padding进行解码，并转换成utf-8编码
    if(padding === 1) { //PKCS7 padding解码
      var len = result.length, paddingChars = 0;
      len && (paddingChars = result.charCodeAt(len-1));
      (paddingChars <= 8) && (result = result.substring(0, len - paddingChars));
    }
    //转换成UTF-8编码
    result = decodeURIComponent(escape(result));
  }
  return result;
} //end of des
//des_createKeys
//this takes as input a 64 bit key (even though only 56 bits are used)
//as an array of 2 integers, and returns 16 48 bit keys
function des_createKeys (key) {
  //declaring this locally speeds things up a bit
  var pc2bytes0 = new Array (0,0x4,0x20000000,0x20000004,0x10000,0x10004,0x20010000,0x20010004,0x200,0x204,0x20000200,0x20000204,0x10200,0x10204,0x20010200,0x20010204);
  var pc2bytes1 = new Array (0,0x1,0x100000,0x100001,0x4000000,0x4000001,0x4100000,0x4100001,0x100,0x101,0x100100,0x100101,0x4000100,0x4000101,0x4100100,0x4100101);
  var pc2bytes2 = new Array (0,0x8,0x800,0x808,0x1000000,0x1000008,0x1000800,0x1000808,0,0x8,0x800,0x808,0x1000000,0x1000008,0x1000800,0x1000808);
  var pc2bytes3 = new Array (0,0x200000,0x8000000,0x8200000,0x2000,0x202000,0x8002000,0x8202000,0x20000,0x220000,0x8020000,0x8220000,0x22000,0x222000,0x8022000,0x8222000);
  var pc2bytes4 = new Array (0,0x40000,0x10,0x40010,0,0x40000,0x10,0x40010,0x1000,0x41000,0x1010,0x41010,0x1000,0x41000,0x1010,0x41010);
  var pc2bytes5 = new Array (0,0x400,0x20,0x420,0,0x400,0x20,0x420,0x2000000,0x2000400,0x2000020,0x2000420,0x2000000,0x2000400,0x2000020,0x2000420);
  var pc2bytes6 = new Array (0,0x10000000,0x80000,0x10080000,0x2,0x10000002,0x80002,0x10080002,0,0x10000000,0x80000,0x10080000,0x2,0x10000002,0x80002,0x10080002);
  var pc2bytes7 = new Array (0,0x10000,0x800,0x10800,0x20000000,0x20010000,0x20000800,0x20010800,0x20000,0x30000,0x20800,0x30800,0x20020000,0x20030000,0x20020800,0x20030800);
  var pc2bytes8 = new Array (0,0x40000,0,0x40000,0x2,0x40002,0x2,0x40002,0x2000000,0x2040000,0x2000000,0x2040000,0x2000002,0x2040002,0x2000002,0x2040002);
  var pc2bytes9 = new Array (0,0x10000000,0x8,0x10000008,0,0x10000000,0x8,0x10000008,0x400,0x10000400,0x408,0x10000408,0x400,0x10000400,0x408,0x10000408);
  var pc2bytes10 = new Array (0,0x20,0,0x20,0x100000,0x100020,0x100000,0x100020,0x2000,0x2020,0x2000,0x2020,0x102000,0x102020,0x102000,0x102020);
  var pc2bytes11 = new Array (0,0x1000000,0x200,0x1000200,0x200000,0x1200000,0x200200,0x1200200,0x4000000,0x5000000,0x4000200,0x5000200,0x4200000,0x5200000,0x4200200,0x5200200);
  var pc2bytes12 = new Array (0,0x1000,0x8000000,0x8001000,0x80000,0x81000,0x8080000,0x8081000,0x10,0x1010,0x8000010,0x8001010,0x80010,0x81010,0x8080010,0x8081010);
  var pc2bytes13 = new Array (0,0x4,0x100,0x104,0,0x4,0x100,0x104,0x1,0x5,0x101,0x105,0x1,0x5,0x101,0x105);
  //how many iterations (1 for des, 3 for triple des)
  var iterations = key.length > 8 ? 3 : 1; //changed by Paul 16/6/2007 to use Triple DES for 9+ byte keys
  //stores the return keys
  var keys = new Array (32 * iterations);
  //now define the left shifts which need to be done
  var shifts = new Array (0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0);
  //other variables
  var lefttemp, righttemp, m=0, n=0, temp;
  for (var j=0; j<iterations; j++) { //either 1 or 3 iterations
    var left = (key.charCodeAt(m++) << 24) | (key.charCodeAt(m++) << 16) | (key.charCodeAt(m++) << 8) | key.charCodeAt(m++);
    var right = (key.charCodeAt(m++) << 24) | (key.charCodeAt(m++) << 16) | (key.charCodeAt(m++) << 8) | key.charCodeAt(m++);
    temp = ((left >>> 4) ^ right) & 0x0f0f0f0f; right ^= temp; left ^= (temp << 4);
    temp = ((right >>> -16) ^ left) & 0x0000ffff; left ^= temp; right ^= (temp << -16);
    temp = ((left >>> 2) ^ right) & 0x33333333; right ^= temp; left ^= (temp << 2);
    temp = ((right >>> -16) ^ left) & 0x0000ffff; left ^= temp; right ^= (temp << -16);
    temp = ((left >>> 1) ^ right) & 0x55555555; right ^= temp; left ^= (temp << 1);
    temp = ((right >>> 8) ^ left) & 0x00ff00ff; left ^= temp; right ^= (temp << 8);
    temp = ((left >>> 1) ^ right) & 0x55555555; right ^= temp; left ^= (temp << 1);
    //the right side needs to be shifted and to get the last four bits of the left side
    temp = (left << 8) | ((right >>> 20) & 0x000000f0);
    //left needs to be put upside down
    left = (right << 24) | ((right << 8) & 0xff0000) | ((right >>> 8) & 0xff00) | ((right >>> 24) & 0xf0);
    right = temp;
    //now go through and perform these shifts on the left and right keys
    for (var i=0; i < shifts.length; i++) {
      //shift the keys either one or two bits to the left
      if (shifts[i]) {left = (left << 2) | (left >>> 26); right = (right << 2) | (right >>> 26);}
      else {left = (left << 1) | (left >>> 27); right = (right << 1) | (right >>> 27);}
      left &= -0xf; right &= -0xf;
      //now apply PC-2, in such a way that E is easier when encrypting or decrypting
      //this conversion will look like PC-2 except only the last 6 bits of each byte are used
      //rather than 48 consecutive bits and the order of lines will be according to
      //how the S selection functions will be applied: S2, S4, S6, S8, S1, S3, S5, S7
      lefttemp = pc2bytes0[left >>> 28] | pc2bytes1[(left >>> 24) & 0xf]
        | pc2bytes2[(left >>> 20) & 0xf] | pc2bytes3[(left >>> 16) & 0xf]
        | pc2bytes4[(left >>> 12) & 0xf] | pc2bytes5[(left >>> 8) & 0xf]
        | pc2bytes6[(left >>> 4) & 0xf];
      righttemp = pc2bytes7[right >>> 28] | pc2bytes8[(right >>> 24) & 0xf]
        | pc2bytes9[(right >>> 20) & 0xf] | pc2bytes10[(right >>> 16) & 0xf]
        | pc2bytes11[(right >>> 12) & 0xf] | pc2bytes12[(right >>> 8) & 0xf]
        | pc2bytes13[(right >>> 4) & 0xf];
      temp = ((righttemp >>> 16) ^ lefttemp) & 0x0000ffff;
      keys[n++] = lefttemp ^ temp; keys[n++] = righttemp ^ (temp << 16);
    }
  } //for each iterations
  //return the keys we&#39;ve created
  return keys;
} //end of des_createKeys
function genkey(key, start, end) {
  //8 byte / 64 bit Key (DES) or 192 bit Key
  return {key:pad(key.slice(start, end)),vector: 1};
}
function pad(key) {
  for (var i = key.length; i<24; i++) {
    key+="0";
  }
  return key;
}
var des3iv = &#39;12345678&#39;;
var DES3 = {
  //3DES加密，CBC/PKCS5Padding
  encrypt:function(key,input){
    var genKey = genkey(key, 0, 24);
    return btoa(des(genKey.key, input, 1, 1, des3iv, 1));
  },
  ////3DES解密，CBC/PKCS5Padding
  decrypt:function(key,input){
    var genKey = genkey(key, 0, 24); 
    return des(genKey.key, atob(input), 0, 1, des3iv, 1); 
  }
};

3. Base64.js文件：

/**
 *create by 2014年7月9日 http://javascript.css-js.com/
 *BASE64 Encode and Decode By UTF-8 unicode
 *可以和java的BASE64编码和解码互相转化
 */
  var BASE64_MAPPING = [
    &#39;A&#39;,&#39;B&#39;,&#39;C&#39;,&#39;D&#39;,&#39;E&#39;,&#39;F&#39;,&#39;G&#39;,&#39;H&#39;,
    &#39;I&#39;,&#39;J&#39;,&#39;K&#39;,&#39;L&#39;,&#39;M&#39;,&#39;N&#39;,&#39;O&#39;,&#39;P&#39;,
    &#39;Q&#39;,&#39;R&#39;,&#39;S&#39;,&#39;T&#39;,&#39;U&#39;,&#39;V&#39;,&#39;W&#39;,&#39;X&#39;,
    &#39;Y&#39;,&#39;Z&#39;,&#39;a&#39;,&#39;b&#39;,&#39;c&#39;,&#39;d&#39;,&#39;e&#39;,&#39;f&#39;,
    &#39;g&#39;,&#39;h&#39;,&#39;i&#39;,&#39;j&#39;,&#39;k&#39;,&#39;l&#39;,&#39;m&#39;,&#39;n&#39;,
    &#39;o&#39;,&#39;p&#39;,&#39;q&#39;,&#39;r&#39;,&#39;s&#39;,&#39;t&#39;,&#39;u&#39;,&#39;v&#39;,
    &#39;w&#39;,&#39;x&#39;,&#39;y&#39;,&#39;z&#39;,&#39;0&#39;,&#39;1&#39;,&#39;2&#39;,&#39;3&#39;,
    &#39;4&#39;,&#39;5&#39;,&#39;6&#39;,&#39;7&#39;,&#39;8&#39;,&#39;9&#39;,&#39;+&#39;,&#39;/&#39;
  ];
  /**
   *ascii convert to binary
   */
  var _toBinary = function(ascii){
    var binary = new Array();
    while(ascii > 0){
      var b = ascii%2;
      ascii = Math.floor(ascii/2);
      binary.push(b);
    }
    /*
    var len = binary.length;
    if(6-len > 0){
      for(var i = 6-len ; i > 0 ; --i){
        binary.push(0);
      }
    }*/
    binary.reverse();
    return binary;
  };
  /**
   *binary convert to decimal
   */
  var _toDecimal = function(binary){
    var dec = 0;
    var p = 0;
    for(var i = binary.length-1 ; i >= 0 ; --i){
      var b = binary[i];
      if(b == 1){
        dec += Math.pow(2 , p);
      }
      ++p;
    }
    return dec;
  };
  /**
   *unicode convert to utf-8
   */
  var _toUTF8Binary = function(c , binaryArray){
    var mustLen = (8-(c+1)) + ((c-1)*6);
    var fatLen = binaryArray.length;
    var diff = mustLen - fatLen;
    while(--diff >= 0){
      binaryArray.unshift(0);
    }
    var binary = [];
    var _c = c;
    while(--_c >= 0){
      binary.push(1);
    }
    binary.push(0);
    var i = 0 , len = 8 - (c+1);
    for(; i < len ; ++i){
      binary.push(binaryArray[i]);
    }
    for(var j = 0 ; j < c-1 ; ++j){
      binary.push(1);
      binary.push(0);
      var sum = 6;
      while(--sum >= 0){
        binary.push(binaryArray[i++]);
      }
    }
    return binary;
  };
  var BASE64 = {
      /**
       *BASE64 Encode
       */
      encoder:function(str){
        var base64_Index = [];
        var binaryArray = [];
        for(var i = 0 , len = str.length ; i < len ; ++i){
          var unicode = str.charCodeAt(i);
          var _tmpBinary = _toBinary(unicode);
          if(unicode < 0x80){
            var _tmpdiff = 8 - _tmpBinary.length;
            while(--_tmpdiff >= 0){
              _tmpBinary.unshift(0);
            }
            binaryArray = binaryArray.concat(_tmpBinary);
          }else if(unicode >= 0x80 && unicode <= 0x7FF){
            binaryArray = binaryArray.concat(_toUTF8Binary(2 , _tmpBinary));
          }else if(unicode >= 0x800 && unicode <= 0xFFFF){//UTF-8 3byte
            binaryArray = binaryArray.concat(_toUTF8Binary(3 , _tmpBinary));
          }else if(unicode >= 0x10000 && unicode <= 0x1FFFFF){//UTF-8 4byte
            binaryArray = binaryArray.concat(_toUTF8Binary(4 , _tmpBinary));  
          }else if(unicode >= 0x200000 && unicode <= 0x3FFFFFF){//UTF-8 5byte
            binaryArray = binaryArray.concat(_toUTF8Binary(5 , _tmpBinary));
          }else if(unicode >= 4000000 && unicode <= 0x7FFFFFFF){//UTF-8 6byte
            binaryArray = binaryArray.concat(_toUTF8Binary(6 , _tmpBinary));
          }
        }
        var extra_Zero_Count = 0;
        for(var i = 0 , len = binaryArray.length ; i < len ; i+=6){
          var diff = (i+6)-len;
          if(diff == 2){
            extra_Zero_Count = 2;
          }else if(diff == 4){
            extra_Zero_Count = 4;
          }
          //if(extra_Zero_Count > 0){
          // len += extra_Zero_Count+1;
          //}
          var _tmpExtra_Zero_Count = extra_Zero_Count;
          while(--_tmpExtra_Zero_Count >= 0){
            binaryArray.push(0);
          }
          base64_Index.push(_toDecimal(binaryArray.slice(i , i+6)));
        }
        var base64 = '';
        for(var i = 0 , len = base64_Index.length ; i < len ; ++i){
          base64 += BASE64_MAPPING[base64_Index[i]];
        }
        for(var i = 0 , len = extra_Zero_Count/2 ; i < len ; ++i){
          base64 += &#39;=&#39;;
        }
        return base64;
      },
      /**
       *BASE64 Decode for UTF-8 
       */
      decoder : function(_base64Str){
        var _len = _base64Str.length;
        var extra_Zero_Count = 0;
        /**
         *计算在进行BASE64编码的时候，补了几个0
         */
        if(_base64Str.charAt(_len-1) == &#39;=&#39;){
          //alert(_base64Str.charAt(_len-1));
          //alert(_base64Str.charAt(_len-2));
          if(_base64Str.charAt(_len-2) == &#39;=&#39;){//两个等号说明补了4个0
            extra_Zero_Count = 4;
            _base64Str = _base64Str.substring(0 , _len-2);
          }else{//一个等号说明补了2个0
            extra_Zero_Count = 2;
            _base64Str = _base64Str.substring(0 , _len - 1);
          }
        }
        var binaryArray = [];
        for(var i = 0 , len = _base64Str.length; i < len ; ++i){
          var c = _base64Str.charAt(i);
          for(var j = 0 , size = BASE64_MAPPING.length ; j < size ; ++j){
            if(c == BASE64_MAPPING[j]){
              var _tmp = _toBinary(j);
              /*不足6位的补0*/
              var _tmpLen = _tmp.length;
              if(6-_tmpLen > 0){
                for(var k = 6-_tmpLen ; k > 0 ; --k){
                  _tmp.unshift(0);
                }
              }
              binaryArray = binaryArray.concat(_tmp);
              break;
            }
          }
        }
        if(extra_Zero_Count > 0){
          binaryArray = binaryArray.slice(0 , binaryArray.length - extra_Zero_Count);
        }
        var unicode = [];
        var unicodeBinary = [];
        for(var i = 0 , len = binaryArray.length ; i < len ; ){
          if(binaryArray[i] == 0){
            unicode=unicode.concat(_toDecimal(binaryArray.slice(i,i+8)));
            i += 8;
          }else{
            var sum = 0;
            while(i < len){
              if(binaryArray[i] == 1){
                ++sum;
              }else{
                break;
              }
              ++i;
            }
            unicodeBinary = unicodeBinary.concat(binaryArray.slice(i+1 , i+8-sum));
            i += 8 - sum;
            while(sum > 1){
              unicodeBinary = unicodeBinary.concat(binaryArray.slice(i+2 , i+8));
              i += 8;
              --sum;
            }
            unicode = unicode.concat(_toDecimal(unicodeBinary));
            unicodeBinary = [];
          }
        }
        //---------直接转换为结果
        var strResult = ''; 
        for(var i = 0 , len = unicode.length ; i < len ;++i){ 
           strResult += String.fromCharCode(unicode[i]); 
        }
        return strResult;
      }
  };

运行结果：

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