Boston Key Party CTF 2017: prudentialv2-50

参考：
https://github.com/bl4de/ctf/blob/master/2017/BostonKeyParty_2017/Prudentialv2/Prudentialv2_Cloud_50.md

2015

http://127.0.0.1/~caiqiqi/Boston_Key_Party_CTF_2017/prudentialv2-50/2015/?name[]=caiqiqi&password[]=qqc

源码：

<?php

$flag = 'Congratuations!';
if (isset($_GET['name']) and isset($_GET['password'])) {
    if ($_GET['name'] == $_GET['password'])
        print 'Your password can not be your name.';
    else if (sha1($_GET['name']) === sha1($_GET['password']))
      die('Flag: '.$flag);
    else
        print '<p class="alert">Invalid password.</p>';
} else{
    print 'Please input parameters in url';
}

?>

2017

http://127.0.0.1/~caiqiqi/Boston_Key_Party_CTF_2017/prudentialv2-50/2017/?name[]=caiqiqi&password[]=qqc

与2015相比，加入了string强制类型转换，必须构造两个不同的字符串但是sha1值相同。
参考：
http://blog.csdn.net/caiqiiqi/article/details/68953730
源码:

<?php

if (isset($_GET['name']) and isset($_GET['password'])) {
    $name = (string)$_GET['name'];
    $password = (string)$_GET['password'];

    if ($name == $password) {
        print 'Your password can not be your name.';
    } else if (sha1($name) === sha1($password)) {
      die('Flag: '.$flag);
    } else {
        print '<p class="alert">Invalid password.</p>';
    }
}

?>