最近搞一点东西要用到对称加密，于是在网上找到一个不错的对称加密方法，分享给大家。

/*** 简单对称加密算法之加密* @param String $string 需要加密的字串* @param String $skey 加密EKY* @return String*/
function encode($string = '', $skey = 'cxphp') {$strArr = str_split(base64_encode($string));$strCount = count($strArr);foreach (str_split($skey) as $key => $value)$key < $strCount && $strArr[$key].=$value;return str_replace(array('=', '+', '/'), array('O0O0O', 'o000o', 'oo00o'), join('', $strArr));
}/*** 简单对称加密算法之解密* @param String $string 需要解密的字串* @param String $skey 解密KEY* @return String*/
function decode($string = '', $skey = 'cxphp') {$strArr = str_split(str_replace(array('O0O0O', 'o000o', 'oo00o'), array('=', '+', '/'), $string), 2);$strCount = count($strArr);foreach (str_split($skey) as $key => $value)$key <= $strCount  && isset($strArr[$key]) && $strArr[$key][1] === $value && $strArr[$key] = $strArr[$key][0];return base64_decode(join('', $strArr));
}echo '<pre>';
echo "encode : " . ($enstring = encode($str)) . '<br />';
echo "decode : " . decode($enstring);
die();

安全URL编码

/*** 安全URL编码* @param string $data* @return string*/
function encode($data) {return str_replace(array('+', '/', '='), array('-', '_', ''), base64_encode(serialize($data)));
}function decode($string) {$data = str_replace(array('-', '_'), array('+', '/'), $string);$mod4 = strlen($data) % 4;($mod4) && $data .= substr('====', $mod4);return unserialize(base64_decode($data));
}

UTF8字符串加密

/*** UTF8字符串加密* @param string $string* @return string*/
function encode($string) {$chars = '';$len = strlen($string = iconv('utf-8', 'gbk', $string));for ($i = 0; $i < $len; $i++) {$chars .= str_pad(base_convert(ord($string[$i]), 10, 36), 2, 0, 0);}return strtoupper($chars);
}function decode($string) {$chars = '';foreach (str_split($string, 2) as $char) {$chars .= chr(intval(base_convert($char, 36, 10)));}return iconv('gbk', 'utf-8', $chars);
}

别的方法

//字符串加密
function lockString($txt,$key)
{$chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-=+";$nh = rand(0,64);$ch = $chars[$nh];$mdKey = md5($key.$ch);$mdKey = substr($mdKey,$nh%8, $nh%8+7);$txt = base64_encode($txt);$tmp = '';$i=0;$j=0;$k = 0;for ($i=0; $i<strlen($txt); $i++) {$k = $k == strlen($mdKey) ? 0 : $k;$j = ($nh+strpos($chars,$txt[$i])+ord($mdKey[$k++]))%64;$tmp .= $chars[$j];}return urlencode($ch.$tmp);
}function unlockString($txt,$key)
{$txt = urldecode($txt);$chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-=+";$ch = $txt[0];$nh = strpos($chars,$ch);$mdKey = md5($key.$ch);$mdKey = substr($mdKey,$nh%8, $nh%8+7);$txt = substr($txt,1);$tmp = '';$i=0;$j=0; $k = 0;for ($i=0; $i<strlen($txt); $i++) {$k = $k == strlen($mdKey) ? 0 : $k;$j = strpos($chars,$txt[$i])-$nh - ord($mdKey[$k++]);while ($j<0) $j+=64;$tmp .= $chars[$j];}return base64_decode($tmp);
}

auth_code优化版

/*** @param string $string  加密字符串内容* @param string $operation 加密或者解密* @param string $key 私钥* @param int $expiry 过期时间/秒 0为永不过期* @return false|string*/
function auth_code(string $string, $operation = 'DECODE', $key = '', $expiry = 0)
{$cakey_length = 4;$key = md5($key);$keys = md5(substr($key, 0, 16));$keytab = md5(substr($key, 16, 16));if ($operation === 'DECODE') {$key_str = substr($string, 0, $cakey_length);} else {$key_str = substr(md5(microtime()), -$cakey_length);}$keycode = $cakey_length ? $key_str : '';$cryptic = $keys . md5($keys . $keycode);$key_length = strlen($cryptic);$string = $operation === 'DECODE' ? base64_decode(substr($string, $cakey_length)) : sprintf('%010d', $expiry ? $expiry + time() : 0) . substr(md5($string . $keytab), 0, 16) . $string;$string_length = strlen($string);$result = '';$box = range(0, 255);$render = array();for ($i = 0; $i <= 255; $i++) {$render[$i] = ord($cryptic[$i % $key_length]);}for ($j = $i = 0; $i < 256; $i++) {$j = ($j + $box[$i] + $render[$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 ($operation === 'DECODE') {if ((strpos($result, 0) === 0 || substr($result, 0, 10) - time() > 0) && strpos(md5(substr($result, 26) . $keytab), substr($result, 10, 16)) === 0) {return substr($result, 26);}return '';}return $keycode . str_replace('=', '', base64_encode($result));
}