php对文件进行hash运算的方法

2024-05-04 23:33:53

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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(!empty($_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($_POST['exphash']!=='none' && !empty($_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>