Detailed explanation of usage and examples of cookie information security for PHP user login

This article mainly introduces the cookie information security of PHP user login, and introduces the two cookie information security protection techniques of cookie encryption and token protection. Friends in need can refer to it

Everyone knows the user After logging in, user information will generally be saved in cookies, because cookies are saved on the client side, and cookies can be freely changed on the client side using the browser. This will cause the risk of user cookies being forged, which may allow forgery cookies to log in. Any user's account.

Let’s talk about some common methods to prevent users from logging in cookie information security:

1. Cookie information encryption method

Cookie information encryption method is Use an encryption method to encrypt user information and then store the cookie. In this way, even if the forger obtains the cookie, he can only use the cookie within the validity period of the cookie and cannot forge additional cookie information.

Attached here is an encryption function:

<?php
function authcode($string, $operation = &#39;DECODE&#39;, $key = &#39;&#39;, $expiry = 0) {
  // 动态密匙长度，相同的明文会生成不同密文就是依靠动态密匙
  $ckey_length = 4;
  // 密匙
  $key = md5($key ? $key : $GLOBALS[&#39;discuz_auth_key&#39;]);
  // 密匙a会参与加解密
  $keya = md5(substr($key, 0, 16));
  // 密匙b会用来做数据完整性验证
  $keyb = md5(substr($key, 16, 16));
  // 密匙c用于变化生成的密文
  $keyc = $ckey_length ? ($operation == &#39;DECODE&#39; ? substr($string, 0, $ckey_length):
substr(md5(microtime()), -$ckey_length)) : &#39;&#39;;
  // 参与运算的密匙
  $cryptkey = $keya.md5($keya.$keyc);
  $key_length = strlen($cryptkey);
  // 明文，前10位用来保存时间戳，解密时验证数据有效性，10到26位用来保存$keyb(密匙b)，
//解密时会通过这个密匙验证数据完整性
  // 如果是解码的话，会从第$ckey_length位开始，因为密文前$ckey_length位保存 动态密匙，以保证解密正确
  $string = $operation == &#39;DECODE&#39; ? base64_decode(substr($string, $ckey_length)) :
sprintf(&#39;%010d&#39;, $expiry ? $expiry + time() : 0).substr(md5($string.$keyb), 0, 16).$string;
  $string_length = strlen($string);
  $result = &#39;&#39;;
  $box = range(0, 255);
  $rndkey = array();
  // 产生密匙簿
  for($i = 0; $i <= 255; $i++) {
    $rndkey[$i] = ord($cryptkey[$i % $key_length]);
  }
  // 用固定的算法，打乱密匙簿，增加随机性，好像很复杂，实际上对并不会增加密文的强度
  for($j = $i = 0; $i < 256; $i++) {
    $j = ($j + $box[$i] + $rndkey[$i]) % 256;
    $tmp = $box[$i];
    $box[$i] = $box[$j];
    $box[$j] = $tmp;
  }
  // 核心加解密部分
  for($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;
    // 从密匙簿得出密匙进行异或，再转成字符
    $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
  }
  if($operation == &#39;DECODE&#39;) {
    // 验证数据有效性，请看未加密明文的格式
    if((substr($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 &#39;&#39;;
    }
  } else {
    // 把动态密匙保存在密文里，这也是为什么同样的明文，生产不同密文后能解密的原因
    // 因为加密后的密文可能是一些特殊字符，复制过程可能会丢失，所以用base64编码
    return $keyc.str_replace(&#39;=&#39;, &#39;&#39;, base64_encode($result));
  }
}
$str = &#39;abcdef&#39;;
$key = &#39;www.jb51.net&#39;;
echo $jm = authcode($str,&#39;ENCODE&#39;,$key,0); //加密
echo "
";
echo authcode($jm ,&#39;DECODE&#39;,$key,0); //解密
?>

So that when setting cookies for user information, they cannot be forged:

<?php
$user = array("uid"=-->$uid,"username"=>$username);
$user = base64_encode(serialize($user));
$user = authcode($user,&#39;ENCODE&#39;,&#39;www.jb51.net&#39;,0); //加密
setcookie("user",$user,time()+3600*24);
?>

2. Use encryption The token protects the cookie

$hash = md5($uid.time());//加密令牌值
$hash_expire =time()+3600*24;//加密令牌值为一天有效期
$user = array("uid"=>$uid,"username"=>$username,"hash"=>$hash);
$user = base64_encode(serialize($user));
setcookie("user",$user,$hash_expr);

Then store $hash and $hash_expire in the corresponding fields of hash and hash_expire in the member table. It can also be stored in nosql and session

User forgery When using cookies, the hash cannot be forged, and the forged hash is inconsistent with the database.

Every time the user logs in, the hash value will not be updated during the validity period of this hash_expire, and it will be updated when it expires

Summary: That’s it for this article The entire content of the article is hoped to be helpful to everyone's study.

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