Javascript实现base64的加密解密方法

base64 加密解密

下方是 base64 用 javascript 写出来的函数和方法。

//加密、解密算法封装：
function Base64() {  
  // private property  
  _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";  
  // 公共编码方法 
  this.encode = function (input) {  
    var output = "";  
    var chr1, chr2, chr3, enc1, enc2, enc3, enc4;  
    var i = 0;  
    input = _utf8_encode(input);  
    while (i < input.length) {  
      chr1 = input.charCodeAt(i++);  
      chr2 = input.charCodeAt(i++);  
      chr3 = input.charCodeAt(i++);  
      enc1 = chr1 >> 2;  
      enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);  
      enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);  
      enc4 = chr3 & 63;  
      if (isNaN(chr2)) {  
          enc3 = enc4 = 64;  
      } else if (isNaN(chr3)) {  
          enc4 = 64;  
      }  
      output = output +  
      _keyStr.charAt(enc1) + _keyStr.charAt(enc2) +  
      _keyStr.charAt(enc3) + _keyStr.charAt(enc4);  
    }  
    return output;  
  }  

  // 公共解码方法
  this.decode = function (input) {  
    var output = "";  
    var chr1, chr2, chr3;  
    var enc1, enc2, enc3, enc4;  
    var i = 0;  
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");  
    while (i < input.length) {  
      enc1 = _keyStr.indexOf(input.charAt(i++));  
      enc2 = _keyStr.indexOf(input.charAt(i++));  
      enc3 = _keyStr.indexOf(input.charAt(i++));  
      enc4 = _keyStr.indexOf(input.charAt(i++));  
      chr1 = (enc1 << 2) | (enc2 >> 4);  
      chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);  
      chr3 = ((enc3 & 3) << 6) | enc4;  
      output = output + String.fromCharCode(chr1);  
      if (enc3 != 64) {  
        output = output + String.fromCharCode(chr2);  
      }  
      if (enc4 != 64) {  
        output = output + String.fromCharCode(chr3);  
      }
    }  
    output = _utf8_decode(output);  
    return output;  
  }  

  // UTF-8 编码的私有方法  
  _utf8_encode = function (string) {  
    string = string.replace(/\r\n/g,"\n");  
    var utftext = "";  
    for (var n = 0; n < string.length; n++) {  
      var c = string.charCodeAt(n);  
      if (c < 128) {  
        utftext += String.fromCharCode(c);  
      } else if((c > 127) && (c < 2048)) {  
        utftext += String.fromCharCode((c >> 6) | 192);  
        utftext += String.fromCharCode((c & 63) | 128);  
      } else {  
        utftext += String.fromCharCode((c >> 12) | 224);  
        utftext += String.fromCharCode(((c >> 6) & 63) | 128);  
        utftext += String.fromCharCode((c & 63) | 128);  
      }
    }  
    return utftext;  
  }  

  // UTF-8 解码的私有方法  
  _utf8_decode = function (utftext) {  
    var string = "";  
    var i = 0;  
    var c = c1 = c2 = 0;  
    while ( i < utftext.length ) {  
      c = utftext.charCodeAt(i);  
      if (c < 128) {  
        string += String.fromCharCode(c);  
        i++;  
      } else if((c > 191) && (c < 224)) {  
        c2 = utftext.charCodeAt(i+1);  
        string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));  
        i += 2;  
      } else {  
        c2 = utftext.charCodeAt(i+1);  
        c3 = utftext.charCodeAt(i+2);  
        string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));  
        i += 3;  
      }  
    }  
    return string;  
  }  
}

加密解密方法使用：

1.加密

var str = '码云笔记 mybj123';  
var base = new Base64();  
var result = base.encode(str);  
//document.write(result);

2. 解密

var result2 = base.decode(result);  
document.write(result2);