下载时在 Zend 框架中解密文件上传

Question

我正在制作一个具有文件上传功能的 zend 项目，并且客户希望在没有扩展名的情况下加密和上传文件。我使用以下代码完美地做到了这一点：

$upload = new Zend_File_Transfer_Adapter_Http ();
$salt = $upload->getHash('md5', 'file_name');
$upload->addFilter('Rename', array('target' => APPLICATION_PATH . '/../../uploads/presentations/'.$salt));
$upload->addFilter('Encrypt', array('adapter' => 'mcrypt', 'key' => $constants->encryption_key));
$upload->receive ();

现在一切正常，我只需使用以下代码下载文件

$filename = 'example_presentation_file.ppt'; //original name in db. by the way this coming from database
$hash = '85be69db87a43265a44be1482cc6d819'; //changed file name when uploaded with this
$mime = 'application/octet-stream';
$file_path = APPLICATION_PATH . '/../../uploads/presentations/'.$hash;
header('Content-Type: "'.$mime.'"');
header('Content-Disposition: attachment; filename="'.$filename.'"');
header("Content-Transfer-Encoding: binary");
header('Expires: 0');
header('Pragma: no-cache');
$size = filesize($file_path);

if(isset($_SERVER['HTTP_RANGE']))
{
    list($a, $range) = explode("=",$_SERVER['HTTP_RANGE'],2);
    list($range) = explode(",",$range,2);
    list($range, $range_end) = explode("-", $range);
    $range = intval($range);
    if(!$range_end) {
        $range_end = $size-1;
    }
    else {
        $range_end = intval($range_end);
    }
    $new_length = $range_end-$range+1;
    header("HTTP/1.1 206 Partial Content");
    header("Content-Length: $new_length");
    header("Content-Range: bytes $range-$range_end/$size");
}
else {
    $new_length = $size;
    header("Content-Length: ".$size);
}
@ob_end_clean();
$speed = false;
$chunksize = ($speed?($speed * 1024):(1024 * 1024)) ;
$bytes_send = 0;
$buffer = "";
if ($file = fopen($file_path, 'r')) {
    if(isset($_SERVER['HTTP_RANGE'])) {
        fseek($file, $range);
    }
    while(!feof($file) && (!connection_aborted()) && ($bytes_send<$new_length)) {
        $buffer = fread($file, $chunksize);
        print($buffer);
        flush();
        if($speed) {    
            if($type!=2) sleep(1);
        }
        $bytes_send += strlen($buffer);
    }
    fclose($file);
}

这段代码运行良好，可以下载文件，但是当我在 powerpoint 中打开该文件时，它没有打开它并显示错误。

关键是，如果我禁用文件加密，我打开得很好，但这是必要的。我只是想知道如何在运行时解密文件（只是当用户下载它而不是永远）。

谢谢。

Answer 1

我建议以下工作流程：

1. 临时解密加密文件并保存在某处
2. 将此解密文件发送给客户端
3. 从文件系统中删除解密文件

例子：

<?php

/* ... */

$options = array(
'adapter' => 'mcrypt', 
'key'     =>  $constants->encryption_key);


$decrypt = new Zend_Filter_File_Decrypt($options);

// temp. decrypt file and save it on the disc
$decrypted_file_path = APPLICATION_PATH . '/../../uploads/presentations/'. $filename;
$decrypt->setFilename($decrypted_file_path);

// encrypted file location
$decrypt->filter($file_path);

/* your code: Send $decrypted_file_path to the client */

// remove decrypted file
unlink($decrypted_file_path);