Crypt为两个不同(相似)密码返回相同的哈希值

Question

我有一个使用crypt()的问题,如果用户有密码(本例中为password1),并且将其更改为password2,则哈希返回相同的结果.您可以在此处测试:OLD LINK 键入password1作为当前密码,password2作为新密码并确认密码,您将看到结果.如果输入完全不相似的密码,则没有问题.我知道还有其他方法可以使用哈希密码等.我比任何事都更好奇.我的代码如下:

<?php

$oldpassword="password1";

echo "<form method=\"post\">
<p>Enter Current Password: <input type=\"password\" name=\"currentpassword\" /></p>
<p>Enter New Password: <input type=\"password\" name=\"password\" /></p>
<p>Confirm New Password: <input type=\"password\" name=\"confirmpassword\" /></p>
<p><input type=\"submit\" value=\"Change Password\"></p>
</form>";

$user_id = $_SESSION['user_id'];
$pass=$_POST['password'];
$salt = 'xxxxx';
$currentpassword = crypt($_POST['currentpassword'], $salt);
$oldpassword = crypt($oldpassword, $salt);
if(isset($_POST['password'])) {
    if ($currentpassword !== $oldpassword) {
        echo "The password you entered for current password does not match our records.";
    }
    else {
        if ($_POST['password'] && $_POST['confirmpassword']) {
            if ($_POST['password'] == $_POST['confirmpassword']) {
            $hash = crypt($pass, $salt);
                if ($hash == $currentpassword) {
                    echo "Current Password:&nbsp;";
                    var_dump($_POST['currentpassword']);
                    echo "<br/>";
                    echo "New Password:&nbsp;";
                    var_dump($_POST['password']);
                    echo "<br/>";
                    echo "New Hash:&nbsp";
                    var_dump($hash);
                    echo "<br/>";
                    echo "Current Password Hash:&nbsp";
                    var_dump($currentpassword);
                    echo "<br/>";
                    echo "<hr/>";
                    echo "Your new password cannot be the same as your current password.";
                }
                else {
                    echo "Your password has been changed successfully<br/>";
                }
            } else {
                echo "Your passwords do not match. Please try again.";
            }
        }
    }
}

?>

Answer 1

要使用地穴,你必须提供适当的盐.每种算法都有自己的盐格式.我的猜测是你使用很少的随机字符作为盐,这与任何高级算法都不匹配,因此php将你的盐减少到前2个字符并回退到基本DES算法.DES算法散列最多8个字符和两个password1和password29个字符长,所以只password从两个所使用的,因此相同的散列.

解决方案:使用适当的salt格式获得最强的可用算法,为每个密码生成随机盐

推荐的解决方案:https://github.com/ircmaxell/password_compat(适用于php 5.3.7 - 5.4.x)和切换到php 5.5之后:http://php.net/password_hash