To have some sort of privacy while sending/receiving messages (or files) using encryption is the first choice.
Below you can find a very simple PHP web application that allows you to encrypt/decrypt a file using your web browser (and a web server hosting the page).
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<?php $ALGORITHM = 'AES-128-CBC'; $IV = '12dasdq3g5b2434b'; $error = ''; if (isset($_POST) && isset($_POST['action'])) { $password = isset($_POST['password']) && $_POST['password']!='' ? $_POST['password'] : null; $action = isset($_POST['action']) && in_array($_POST['action'],array('c','d')) ? $_POST['action'] : null; $file = isset($_FILES) && isset($_FILES['file']) && $_FILES['file']['error'] == UPLOAD_ERR_OK ? $_FILES['file'] : null; if ($password === null) { $error .= 'Invalid Password<br>'; } if ($action === null) { $error .= 'Invalid Action<br>'; } if ($file === null) { $error .= 'Errors occurred while elaborating the file<br>'; } if ($error === '') { $contenuto = ''; $nomefile = ''; $contenuto = file_get_contents($file['tmp_name']); $filename = $file['name']; switch ($action) { case 'c': $contenuto = openssl_encrypt($contenuto, $ALGORITHM, $password, 0, $IV); $filename = $filename . '.crypto'; break; case 'd': $contenuto = openssl_decrypt($contenuto, $ALGORITHM, $password, 0, $IV); $filename = preg_replace('#\.crypto$#','',$filename); break; } if ($contenuto === false) { $error .= 'Errors occurred while encrypting/decrypting the file '; } if ($error === '') { header("Pragma: public"); header("Pragma: no-cache"); header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0"); header("Cache-Control: post-check=0, pre-check=0", false); header("Expires: 0"); header("Content-Type: application/octet-stream"); header("Content-Disposition: attachment; filename=\"" . $filename . "\";"); $size = strlen($contenuto); header("Content-Length: " . $size); echo $contenuto; die; } } } ?> <html> <head> <title>Encrypt/Decrypt file</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"> <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css"> </head> <body> <div class="container"> <div class="row"> <div class="col-12" > <h1>Utility to encrypt/decrypt a file</h1> </div> </div> <?php if ($error != '') { ?> <div class="row"> <div class="col-12 alert alert-danger" role="alert"> <?php echo ($error); ?> </div> </div> <?php } ?> <form class="form" enctype="multipart/form-data" method="post" id="form1" name="form1" auto-complete="off"> <div class="form-row"> <div class="form-group"> <label for="file">File</label> <input type="file" name="file" id="file" placeholder="Choose a file" required class="form-control-file"/> </div> </div> <div class="form-row"> <div class="form-group"> <label for="password">Password</label> <input type="password" name="password" id="password" placeholder="Insert password" required class="form-control" /> </div> </div> <div class="form-row"> <div class="form-group"> <label for="action">Action</label> <select name="action" id="action" required class="form-control"> <option value="">-- Choose --</option> <option value="c">Encrypt</option> <option value="d">Decrypt</option> </select> </div> </div> <div class="form-row"> <button type="submit" class="btn btn-primary" onclick="setTimeout('document.form1.reset();',1000)">Execute</button> <button type="reset" class="btn btn-reset">Reset</button> </div> </form> </div> <script type="text/javascript" src="https://code.jquery.com/jquery-3.3.1.slim.min.js"></script> <script type="text/javascript" src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.bundle.min.js"></script> </body> </html> |