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其他语言如何解密PHP多字符串的异或加密-php字符串异或运算原理

Jun 06, 2016 pm 07:37 PM
php encryption how string XOR Decrypt language

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

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

    注:如果在PHP下欲将二进制11转换为此结果需要使用附录一的函数bin2str,网上也有其他字符串转二进制的方法,但有的在此处使用结果不一致,需注意

上面是两个单个字符串的简单异或运算,网上也有介绍,但是关于多个字符串的异或运算,网上没查到相关资料,楼主在这儿大致解释一下PHP这么搞的原理,其他语言照这个思路和逻辑一样能解密PHP的^

'abc' ^ 'def':
     a,b,c的ASCII分别为97,98,99,转换2进制后分别为:1100001,1100010,1100011
     d,e,f的ASCII分别为100,101,102,转换2进制后分别为:1100100,1100101,1100110
    按左边对其,分别比较a和d,b和e,c和f的ASCII码二进制的异或值:101 111 101
    然后对这三个分别二进制转字符串进行拼接

'abc' ^ 'defgh':
    有的语言也能实现上面的字符串异或运算,当看到这个就会愣了一下,因为发现为啥两边字符数不一样也能异或运算
    很简单 php按左对齐只比较两者的短的字符串的那个长度,后面的都舍去了

楼主个人网站:https://www.riji.info
function str2bin($str = ''){
    $bin_arr = array();
    $str_arr = preg_split('//u', $str, 0, PREG_SPLIT_NO_EMPTY);
    foreach ($str_arr as $val) {
        if (ord($val) > 127) {
            $bin_arr[] = hex2bin(str_replace('%', '', urlencode($val)));
        } else {
            $bin_arr[] = decbin(ord($val));
        }
    }
    return implode(' ', $bin_arr);
}
 
function bin2str($bin_str = ''){
    $str = '';
    $bin_str = explode(' ', $bin_str);
    foreach ($bin_str as $val) {
        if (bindec($val) < 127) {
            $str .= chr(bindec($val));
        } else {
            $str .= urldecode('%' . implode('%', str_split(bin2hex($val), 2)));
        }
    }
    return $str;
}
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