php对文件进行hash运算的方法

发布:smiling　来源: PHP粉丝网　添加日期：2021-05-21 11:33:27　浏览: 评论：0　

这篇文章主要介绍了php对文件进行hash运算的方法,涉及针对文件的hash运算技巧,非常具有实用价值,需要的朋友可以参考下。

本文实例讲述了php对文件进行hash运算的方法，分享给大家供大家参考，具体如下：

这段代码非常有用，如果你下载了一个文件，网站提供了hash结果，你可以对你下载下来的文件进行hash运算，以验证下载的文件是否正确。

<html>

<head>

  <title>Hash (Check) Files</title>

  <style type='text/css'>

   #ok{color:green;}

   #nono{color:red;}

  </style>

</head>

<body>

<?php

   if(!emptyempty($_FILES)){

   if ($_FILES["file"]["error"] > 0){

    switch($_FILES["file"]["error"]){

     case 1:

     echo "<b id='nono'>Error: The uploaded file exceeds the upload_max_filesize directive in php.ini</b><br>";

     break;

     case 2:

     echo "<b id='nono'>Error: The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form.</b><br>";

     break;

     case 3:

     echo "<b id='nono'>Error: The uploaded file was only partially uploaded.</b><br>";

     break;

     case 4:

     echo "<b id='nono'>Error: No file was uploaded.</b><br>";

     break;

     case 6:

     echo "<b id='nono'>Error: Missing a temporary folder.</b><br>";

     break;

     case 7:

     echo "<b id='nono'>Error: Failed to write file to disk.</b><br>";

     break;

     case 8:

     echo "<b id='nono'>Error: A PHP extension stopped the file upload.</b><br>";

     break;

     default:

     echo "<b id='nono'>Unknown error occured.</b><br>";

    }

   } else {

    echo 'Upload: ' . $_FILES['file']['name'] . '<br>';

    echo 'Type: ' . $_FILES['file']['type'] . '<br>';

    echo 'Size: ' . (round($_FILES['file']['size'] / 1024, 2)) . ' Kb<br><br>';

    if(array_search($_POST['algo'], hash_algos())===false){

    echo 'Unknown hashing algorithm requested.<br>';

    } else {

    echo 'Hashing Algorithm: '. $_POST['algo'] . '<br>';

    $hash = hash_file($_POST['algo'], $_FILES['file']['tmp_name']);

    echo 'Calculated hash: ' . $hash . '<br>';

    if($_POST['exphash']!=='none' && !emptyempty($_POST['exphash'])){

      echo 'Expected hash:   ' . $_POST['exphash'] . '<br><br>';

      echo ($hash==$_POST['exphash'])? '<b id="ok">Hash matched expected value.</b>' : '<b id="nono">Hash did not match expected value.</b>';

      echo '<br>';

    }

    }

   }

   ?>

   <br>

   <button onClick="document.location.reload(true)">Again</button>

    <?php

   } else {

  ?>

  <form action="" method="post" enctype="multipart/form-data">

   <input type="hidden" name="exphash" value="none">

   <label for="file">Filename:</label>

   <input type="file" name="file" id="file">

   <input type="submit" name="submit" value="Submit" /><br>

   <label>Expected hash(optional): <input type="text" name="exphash" size="100"></label>

   <br><br>Choose an algorithm (This is the list of all the available algorithms in your php installation)<br>

   <?php

   foreach(hash_algos() as $algo){

    if($algo=='md5'){

    echo "<label><input type='radio' name='algo' value='$algo' checked='checked'>$algo</label><br>";

    } else {

    echo "<label><input type='radio' name='algo' value='$algo'>$algo</label><br>";

    }

   }

   ?>

  </form>

<?php

   }

  ?>

</body>

</html>