jQuery Base 64 加密解密的实现

javascript原生的api本来就支持,Base64,但是由于之前的javascript局限性，导致Base64基本中看不中用。当前html5标准正式化之际，Base64将有较大的转型空间,对于Html5 Api中出现的如FileReader Api, 拖拽上传,甚至是Canvas,Video截图都可以实现。

好了，前言说了一大堆，开发者需要重视：

一.我们来看看，在javascript中如何使用Base64转码

var str = 'javascript';
window.btoa(str)
//转码结果 "amF2YXNjcmlwdA=="
window.atob("amF2YXNjcmlwdA==")
//解码结果 "javascript"

二.对于转码来说，Base64转码的对象只能是字符串，因此来说，对于其他数据还有这一定的局限性，在此特别需要注意的是对Unicode转码。

var str = "China，中国"
window.btoa(str)

Uncaught DOMException: Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.

很明显，这种方式是不行的，那么如何让他支持汉字呢，这就要使用window.encodeURIComponent和window.decodeURIComponent

var str = "China，中国";
window.btoa(window.encodeURIComponent(str))
//"Q2hpbmElRUYlQkMlOEMlRTQlQjglQUQlRTUlOUIlQkQ="
window.decodeURIComponent(window.atob('Q2hpbmElRUYlQkMlOEMlRTQlQjglQUQlRTUlOUIlQkQ='))
//"China，中国"

以下是jQuery.Base64的实现

/**
 * base64加密解密
 */
(function ($) {
    var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
        a256 = '',
        r64 = [256],
        r256 = [256],
        i = 0;

    var UTF8 = {
        encode: function (strUni) {
            var strUtf = strUni.replace(/[\u0080-\u07ff]/g,
                function (c) {
                    var cc = c.charCodeAt(0);
                    return String.fromCharCode(0xc0 | cc >> 6, 0x80 | cc & 0x3f);
                })
                .replace(/[\u0800-\uffff]/g,
                    function (c) {
                        var cc = c.charCodeAt(0);
                        return String.fromCharCode(0xe0 | cc >> 12, 0x80 | cc >> 6 & 0x3F, 0x80 | cc & 0x3f);
                    });
            return strUtf;
        },
        decode: function (strUtf) {
            var strUni = strUtf.replace(/[\u00e0-\u00ef][\u0080-\u00bf][\u0080-\u00bf]/g,
                function (c) {
                    var cc = ((c.charCodeAt(0) & 0x0f) << 12) | ((c.charCodeAt(1) & 0x3f) << 6) | (c.charCodeAt(2) & 0x3f);
                    return String.fromCharCode(cc);
                })
                .replace(/[\u00c0-\u00df][\u0080-\u00bf]/g,
                    function (c) {
                        var cc = (c.charCodeAt(0) & 0x1f) << 6 | c.charCodeAt(1) & 0x3f;
                        return String.fromCharCode(cc);
                    });
            return strUni;
        }
    };

    while (i < 256) {
        var c = String.fromCharCode(i);
        a256 += c;
        r256[i] = i;
        r64[i] = b64.indexOf(c);
        ++i;
    }

    function code(s, discard, alpha, beta, w1, w2) {
        s = String(s);
        var buffer = 0,
            i = 0,
            length = s.length,
            result = '',
            bitsInBuffer = 0;

        while (i < length) {
            var c = s.charCodeAt(i);
            c = c < 256 ? alpha[c] : -1;

            buffer = (buffer << w1) + c;
            bitsInBuffer += w1;

            while (bitsInBuffer >= w2) {
                bitsInBuffer -= w2;
                var tmp = buffer >> bitsInBuffer;
                result += beta.charAt(tmp);
                buffer ^= tmp << bitsInBuffer;
            }
            ++i;
        }
        if (!discard && bitsInBuffer > 0) result += beta.charAt(buffer << (w2 - bitsInBuffer));
        return result;
    }

    var Plugin = $.base64 = function (dir, input, encode) {
        return input ? Plugin[dir](input, encode) : dir ? null : this;
    };

    Plugin.btoa = Plugin.encode = function (plain, utf8encode) {
        plain = Plugin.raw === false || Plugin.utf8encode || utf8encode ? UTF8.encode(plain) : plain;
        plain = code(plain, false, r256, b64, 8, 6);
        return plain + '===='.slice((plain.length % 4) || 4);
    };

    Plugin.atob = Plugin.decode = function (coded, utf8decode) {
        coded = coded.replace(/[^A-Za-z0-9\+\/\=]/g, "");
        coded = String(coded).split('=');
        var i = coded.length;
        do {
            --i;
            coded[i] = code(coded[i], true, r64, a256, 6, 8);
        } while (i > 0);
        coded = coded.join('');
        return Plugin.raw === false || Plugin.utf8decode || utf8decode ? UTF8.decode(coded) : coded;
    };
}(jQuery));

选项：

$.base64.utf8encode = true;
$.base64.utf8decode = true;

使用方法

加密：

$.base64('encode', 'feil.wang');   //ZmVpbC53YW5n

解密：

$.base64('decode', 'ZmVpbC53YW5n');  //feil.wang