Javascript实现base64的加密解密

//1.加密解密方法使用：//1.加密  
var str = '124中文内容';  
var base = new Base64();  
var result = base.encode(str);  
//document.write(result);  //2.解密  
var result2 = base.decode(result);  
document.write(result2);  
//2.加密、解密算法封装：function Base64() {  // private property  _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";  // public method for encoding  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;  }  // public method for decoding  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;  }  // private method for UTF-8 encoding  _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;  }  // private method for UTF-8 decoding  _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;  }  
}