PHP 加密解密

范例 

$txt = "This is confidential text";
$key = "2023";

$encrypt = passport_encrypt($txt, $key);
echo "加密：" . $encrypt;
echo "
";

$decrypt = passport_decrypt($encrypt, $key);
echo "解密：" . $decrypt;

 输出

加密：VgJWPAU4XSVWelM9BHdXdwBrUWoCOFdlU2VWbgw6VDVQJFU+WWxbPAcrVyQLbgN7AX0=
--------------------------------------------------------------------------
解密：This is confidential text

/**
 * 解密函数
 *
 * @param string $txt
 * @param string $key
 * @return string
 */
function passport_decrypt($txt, $key)
{
    $txt = passport_key(base64_decode($txt), $key);
    $tmp = '';
    for ($i = 0;$i < strlen($txt); $i++) {
        $md5 = $txt[$i];
        $tmp .= $txt[++$i] ^ $md5;
    }
    return $tmp;
}

/**
 * 加密函数
 *
 * @param string $txt
 * @param string $key
 * @return string
 */
function passport_encrypt($txt, $key)
{
    srand((double)microtime() * 1000000);
    $encrypt_key = md5(rand(0, 32000));
    $ctr = 0;
    $tmp = '';
    for($i = 0; $i < strlen($txt); $i++ )
    {
        $ctr = $ctr == strlen($encrypt_key) ? 0 : $ctr;
        $tmp .= $encrypt_key[$ctr].($txt[$i] ^ $encrypt_key[$ctr++]);
    }
    return base64_encode(passport_key($tmp, $key));
}

/**
 * 编码函数
 *
 * @param string $txt
 * @param string $key
 * @return string
 */
function passport_key($txt, $encrypt_key)
{
    $encrypt_key = md5($encrypt_key);
    $ctr = 0;
    $tmp = '';
    for($i = 0; $i < strlen($txt); $i++)
    {
        $ctr = $ctr == strlen($encrypt_key) ? 0 : $ctr;
        $tmp .= $txt[$i] ^ $encrypt_key[$ctr++];
    }
    return $tmp;
}