关于base64加密/解密

答案：尚不支持中文，有待完善。 
<script type="text/javascript">  
var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";  
var base64DecodeChars = new Array(  
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  
 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,  
 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,  
 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,  
 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,  
 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,  
 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);  

function base64Encode(str) {  
 var out, i, len;  
 var c1, c2, c3;  

 len = str.length;  
 i = 0;  
 out = "";  
 while(i < len) {  
 c1 = str.charCodeAt(i++) & 0xff;  
 if(i == len)  
 {  
 out += base64EncodeChars.charAt(c1 >> 2);  
 out += base64EncodeChars.charAt((c1 & 0x3) << 4);  
 out += "==";  
 break;  
 }  
 c2 = str.charCodeAt(i++);  
 if(i == len)  
 {  
 out += base64EncodeChars.charAt(c1 >> 2);  
 out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));  
 out += base64EncodeChars.charAt((c2 & 0xF) << 2);  
 out += "=";  
 break;  
 }  
 c3 = str.charCodeAt(i++);  
 out += base64EncodeChars.charAt(c1 >> 2);  
 out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));  
 out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6));  
 out += base64EncodeChars.charAt(c3 & 0x3F);  
 }  
 return out;  
}  

function base64Decode(str) {  
 var c1, c2, c3, c4;  
 var i, len, out;  

 len = str.length;  
 i = 0;  
 out = "";  
 while(i < len) {  
 /* c1 */  
 do {  
 c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];  
 } while(i < len && c1 == -1);  
 if(c1 == -1)  
 break;  

 /* c2 */  
 do {  
 c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];  
 } while(i < len && c2 == -1);  
 if(c2 == -1)  
 break;  

 out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));  

 /* c3 */  
 do {  
 c3 = str.charCodeAt(i++) & 0xff;  
 if(c3 == 61)  
 return out;  
 c3 = base64DecodeChars[c3];  
 } while(i < len && c3 == -1);  
 if(c3 == -1)  
 break;  

 out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));  

 /* c4 */  
 do {  
 c4 = str.charCodeAt(i++) & 0xff;  
 if(c4 == 61)  
 return out;  
 c4 = base64DecodeChars[c4];  
 } while(i < len && c4 == -1);  
 if(c4 == -1)  
 break;  
 out += String.fromCharCode(((c3 & 0x03) << 6) | c4);  
 }  
 return out;  
}  

var sTemp="http://www.cnlei.com";  
alert("原文："+sTemp+"\n加密："+base64Encode(sTemp)+"\n解密："+base64Decode(base64Encode(sTemp)));  
sTemp="我是枫岩";  
alert("原文："+sTemp+"\n加密："+base64Encode(sTemp)+"\n解密："+base64Decode(base64Encode(sTemp)));  
</script>
  [Ctrl+A 全选 注:如需引入外部Js需刷新才能执行]

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