PHP中哪种加密方法最安全？

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加密解密方法 // 字符串解密加密function authcode($string, $operation='DECODE', $key='', $expiry=0) { $ckey_length=8; // 随机密钥长度取值范围0-32; // 加入随机密钥，可令密文无任何规律，即便是原文和密文完全相同，每次加密后的密文也不相同 $key=md5($key ? $key : 'default_key'); $keya=substr($key, 0, 16); $keyb=substr($key, 16, 16); $keyc=$keya.md5($keyb); $cryptkey=$keyc.substr($key, 0, 16); $iv=substr(md5(substr($key, 0, 16)), 0, 16); if ($operation=='DECODE') { $decrypted=mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $cryptkey, base64_decode($string), MCRYPT_MODE_CBC, $iv); if (substr($decrypted, 0, 16)==substr($keyc, 0, 16)) { $decrypted=substr($decrypted, 16); $decrypted=preg_replace(/[^a-zA-Z0-9]/, , $decrypted); return $decrypted; } } else { $string=substr($string, 0, -16); $string=str_pad($string, 16, chr(0)); $string=mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $cryptkey, $string, MCRYPT_MODE_CBC, $iv); $string=base64_encode($string . substr($keyc, 0, 16)); return $string; } }

//字符串解密加密 function authcode($string, $operation = 'DECODE', $key = '', $expiry = 0) { $ckey_length = 8; // 随机密钥长度 取值 0-32; // 加入随机密钥，可以令密文无任何规律，即便是原文和密钥完全相同，加密结果也会每次不同，增大破解难度。 // 取值越大，密文变动规律越大，密文变化 = 16 的 $ckey_length 次方 // 当此值为 0 时，则不产生随机密钥 $CI = &get_instance(); $key = md5($key ? $key : $CI->config->item('encryption_key')); $keya = md5(substr($key, 0, 16)); $keyb = md5(substr($key, 16, 16)); $keyc = $ckey_length ? ($operation == 'DECODE' ? substr($string, 0, $ckey_length) : substr(md5(microtime()), -$ckey_length)):''; $cryptkey = $keya . md5($keya . $keyc); $key_length = strlen($cryptkey); $string = $operation == 'DECODE' ? base64_decode(substr($string, $ckey_length)) : sprintf('%010d', $expiry ? $expiry + time() : 0) . substr(md5($string . $keyb), 0, 16) . $string; $string_length = strlen($string); $result = ''; $box = range(0, 255); $rndkey = array(); for ($i = 0; $i <= 255; $i++) { $rndkey[$i] = ord($cryptkey[$i % $key_length]); } for ($j = $i = 0; $i < 256; $i++) { $j = ($j + $box[$i] + $rndkey[$i]) % 256; $tmp = $box[$i]; $box[$i] = $box[$j]; $box[$j] = $tmp; } for ($a = $j = $i = 0; $i < $string_length; $i++) { $a = ($a + 1) % 256; $j = ($j + $box[$a]) % 256; $tmp = $box[$a]; $box[$a] = $box[$j]; $box[$j] = $tmp; $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256])); } if ($operation == 'DECODE') { if ((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26) . $keyb), 0, 16)) { return substr($result, 26); } else { return ''; } } else { return $keyc . str_replace('=', '', base64_encode($result)); } }