//'*********************************************************
// 利用BASE64加密解密字符串,
//'*********************************************************
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);
//'*********************************************************
// 20.'加密字符串,如字符串:1234567890
// 'Returns：MTIzNDU2Nzg5MA==
//'*********************************************************
function base64encode(str) {
	str = utf16to8(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);
    }
    out = out.replace("+","%2B")
    return out+"&";
}
//'*********************************************************
// '21 解密字符串,如字符串:MTIzNDU2Nzg5MA==
// 'Returns：1234567890
//'*********************************************************
function base64decode(str) {
    str =str.substring(0,str.length-1);
    re = /%2B/g;             // 创建正则表达式模式。
    str = str.replace(re, "+");  
    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)
        {out = utf8to16(out);
        　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)
       { out = utf8to16(out);
        return out;}
        c4 = base64DecodeChars[c4];
    } while(i < len && c4 == -1);
    if(c4 == -1)
        break;
    out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
    }
    out = utf8to16(out)
    return out;
}

//'*********************************************************
// '2２ 字符串由utf8到utf16 
//'*********************************************************
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;
}
//'*********************************************************
// '23 字符串由utf16到utf8 
//'*********************************************************
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;
}