php,js 对字符串按位异或运算加密解密

异或的符号是^。按位异或运算, 对等长二进制模式按位或二进制数的每一位执行逻辑按位异或操作. 操作的结果是如果某位不同则该位为1, 否则该位为0.

xor运算的逆运算是它本身，也就是说两次异或同一个数最后结果不变，即（a xor b) xor b = a。xor运算可以用于简单的加密，比如我想对我MM说1314520，但怕别人知道，于是双方约定拿我的生日19880516作为密钥。1314520 xor 19880516 = 20665500，我就把20665500告诉MM。MM再次计算20665500 xor 19880516的值，得到1314520，于是她就明白了我的企图。

相同位不同则为1，相同则为0。

00101

11100

（^或者xor）

----------------

11001

运算结果

x <- x # y

y <- x @ y

x <- x @ y

执行了第一句后x变成了x # y。那么第二句实质就是y <- x # y @ y，由于#和@互为逆运算，那么此时的y变成了原来的x。第三句中x实际上被赋值为（x # y) @ x，如果#运算具有交换律，那么赋值后x就变成最初的y了。这三句话的结果是，x和y的位置互换了。

通过这个原理运用PHP可实现简单高效的加密

注意：

PHP语言的^运算符经常用来做加密的运算，解密也直接用^就行，但是和其他语言通信时，其他语言例如objective-c未必能解的出来PHP的^，尤其是当php使用多个字符串如：'abc'^'def',这样的运算时，其他语言少有这种直接可运算的，更不能解的出来
计算原理：
'a'^'b' :
    a和b的ASCII分别为97和98，转换2进制后分别为：1100001,1100010
    然后使用此二位进行异或运算,得到结果：11
    再用把二进制数11转换为字符串
    在windon命令行下计算结果会显示一个乱码

以下为实现方法：

<?php
$k = 'app';
$v = '321';
echo '秘钥：'.$k;
echo '</br>';
echo '明文：'.$v;
echo '</br>';
$key = sha1($k);
echo 'sha1加密秘钥：'.$key;
echo '</br>';
$yihuo = $v ^ $key;
echo '异或运算：'.$yihuo;
echo '</br>';
echo 'base64_encode编码：'.base64_encode($yihuo);

//按位异或运算加密
function xorencrypt( $str, $key ){
    $slen = strlen( $str );
    $klen = strlen( $key );
    $cipher = '';
    for ($i=0;$i<$slen;$i=$i+$klen) {
        $cipher .= substr( $str, $i, $klen )^$key;
    }
    return $cipher;
}

//接收端实现简单的解密
function xordecrypt( $str, $key ){
    $slen = strlen( $str );
    $klen = strlen( $key );
    $plain = '';
    for ($i=0;$i<$slen;$i=$i+$klen) {
        $plain .= $key^substr( $str, $i, $klen );
    }
    return $plain;
}

?>

<script>
    function encodeUTF8(s) {
        var i, r = [], c, x;
        for (i = 0; i < s.length; i++)
            if ((c = s.charCodeAt(i)) < 0x80) r.push(c);
            else if (c < 0x800) r.push(0xC0 + (c >> 6 & 0x1F), 0x80 + (c & 0x3F));
            else {
                if ((x = c ^ 0xD800) >> 10 == 0) //对四字节UTF-16转换为Unicode
                    c = (x << 10) + (s.charCodeAt(++i) ^ 0xDC00) + 0x10000,
                        r.push(0xF0 + (c >> 18 & 0x7), 0x80 + (c >> 12 & 0x3F));
                else r.push(0xE0 + (c >> 12 & 0xF));
                r.push(0x80 + (c >> 6 & 0x3F), 0x80 + (c & 0x3F));
            };
        return r;
    }

    // 字符串加密成 hex 字符串
    function sha1(s) {
        var data = new Uint8Array(encodeUTF8(s))
        var i, j, t;
        var l = ((data.length + 8) >>> 6 << 4) + 16, s = new Uint8Array(l << 2);
        s.set(new Uint8Array(data.buffer)), s = new Uint32Array(s.buffer);
        for (t = new DataView(s.buffer), i = 0; i < l; i++)s[i] = t.getUint32(i << 2);
        s[data.length >> 2] |= 0x80 << (24 - (data.length & 3) * 8);
        s[l - 1] = data.length << 3;
        var w = [], f = [
                function () { return m[1] & m[2] | ~m[1] & m[3]; },
                function () { return m[1] ^ m[2] ^ m[3]; },
                function () { return m[1] & m[2] | m[1] & m[3] | m[2] & m[3]; },
                function () { return m[1] ^ m[2] ^ m[3]; }
            ], rol = function (n, c) { return n << c | n >>> (32 - c); },
            k = [1518500249, 1859775393, -1894007588, -899497514],
            m = [1732584193, -271733879, null, null, -1009589776];
        m[2] = ~m[0], m[3] = ~m[1];
        for (i = 0; i < s.length; i += 16) {
            var o = m.slice(0);
            for (j = 0; j < 80; j++)
                w[j] = j < 16 ? s[i + j] : rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1),
                    t = rol(m[0], 5) + f[j / 20 | 0]() + m[4] + w[j] + k[j / 20 | 0] | 0,
                    m[1] = rol(m[1], 30), m.pop(), m.unshift(t);
            for (j = 0; j < 5; j++)m[j] = m[j] + o[j] | 0;
        };
        t = new DataView(new Uint32Array(m).buffer);
        for (var i = 0; i < 5; i++)m[i] = t.getUint32(i << 2);

        var hex = Array.prototype.map.call(new Uint8Array(new Uint32Array(m).buffer), function (e) {
            return (e < 16 ? "0" : "") + e.toString(16);
        }).join("");
        return hex;
    }

</script>
<script>
    /**
     *
     *  Base64 encode / decode
     *  http://www.webtoolkit.info
     *
     **/
    var Base64 = {

        // private property
        _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="

        // public method for encoding
        , encode: function (input)
        {
            var output = "";
            var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
            var i = 0;

            input = Base64._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 +
                    this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
                    this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);
            } // Whend

            return output;
        } // End Function encode

        // public method for decoding
        ,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 = this._keyStr.indexOf(input.charAt(i++));
                enc2 = this._keyStr.indexOf(input.charAt(i++));
                enc3 = this._keyStr.indexOf(input.charAt(i++));
                enc4 = this._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);
                }

            } // Whend

            output = Base64._utf8_decode(output);

            return output;
        } // End Function decode

        // private method for UTF-8 encoding
        ,_utf8_encode: function (string)
        {
            var utftext = "";
            string = string.replace(/\r\n/g, "\n");

            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);
                }

            } // Next n

            return utftext;
        } // End Function _utf8_encode

        // private method for UTF-8 decoding
        ,_utf8_decode: function (utftext)
        {
            var string = "";
            var i = 0;
            var c, c1, c2, c3;
            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;
                }

            } // Whend

            return string;
        } // End Function _utf8_decode

    }
</script>

<script>
    function xor_enc(str, key) {
        var crytxt = '';
        var k, keylen = key.length;
        for(var i=0; i<str.length; i++) {
            k = i % keylen;
            crytxt += String.fromCharCode(str.charCodeAt(i) ^ key.charCodeAt(k));
        }
        return crytxt;
    }
</script>
<script>
    var k = 'app';
    var key = sha1('app');
    var v = '321';
    var yihuo = xor_enc(v,key);

    console.log('秘钥：'+k);
    console.log('明文：'+v);
    console.log('sha1加密秘钥：'+key);
    console.log('异或运算：'+yihuo);
    console.log('base64_encode编码：'+Base64.encode(yihuo));

</script>

运行效果图：