JS base64 加密和解密

/***
* 加密 base64encode(utf16to8(str))
* 解密 utf8to16(base64decode(str))
*
*
*/
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);  
/** 
 * base64编码 
 * @param {Object} str 
 */  
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;  
}  
/** 
 * base64解码 
 * @param {Object} str 
 */  
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;  
}  
function utf16to8(str) {
　　var out, i, len, c;
　　out = "";
　　len = str.length;
　　for(i = 0; i < len; i++) {
 c = str.charCodeAt(i);
 if ((c >= 0x0001) && (c <= 0x007F)) {
　　 out += str.charAt(i);
 } else if (c > 0x07FF) {
　　 out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
　　 out += String.fromCharCode(0x80 | ((c >>　6) & 0x3F));
　　 out += String.fromCharCode(0x80 | ((c >>　0) & 0x3F));
 } else {
　　 out += String.fromCharCode(0xC0 | ((c >>　6) & 0x1F));
　　 out += String.fromCharCode(0x80 | ((c >>　0) & 0x3F));
 }
　　}
　　return out;
}
function utf8to16(str) {
　　var out, i, len, c;
　　var char2, char3;
　　out = "";
　　len = str.length;
　　i = 0;
　　while(i < len) {
 c = str.charCodeAt(i++);
 switch(c >> 4)
 {
　 case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
　　 // 0xxxxxxx
　　 out += str.charAt(i-1);
　　 break;
　 case 12: case 13:
　　 // 110x xxxx　 10xx xxxx
　　 char2 = str.charCodeAt(i++);
　　 out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
　　 break;
　 case 14:
　　 // 1110 xxxx　10xx xxxx　10xx xxxx
　　 char2 = str.charCodeAt(i++);
　　 char3 = str.charCodeAt(i++);
　　 out += String.fromCharCode(((c & 0x0F) << 12) |
　　　　((char2 & 0x3F) << 6) |
　　　　((char3 & 0x3F) << 0));
　　 break;
 }
　　}
　　return out;
}