How to set and verify file's origin? - cryptography

Can you guys suggest any method for my below problem?
I am developing an application which requires users to download an excel file, modify some content and upload exactly the same file they just download.
The requirement started from the fact that there is macro inside the excel file (which can be changed often), hence I try to make sure they always download and do works with the latest version. Then have to upload that file again.
My system is a web-based application for your reference.

Related

How to read files from anywhere with vue.js

I am trying to read files from my music directory on my PC.
I have tried doing it with the node.js file system module, but it is not working. How do I get it to work?😢
Just a late follow-up. It is possible to read and write files using HTML5 with the FileReader and saveAs(). The browser will open a file dialogue and let the user choose the file, so the user is aware of the file access. It is not possible to read or write to a file without the user's attention.
https://developer.mozilla.org/en-US/docs/Web/API/FileReader
As said by #flame in a comment, it's just impossible, because the browser never have access to the visitor's disk (do you imagine the security issue if it was the case ?).
Vue.js is a Front-end framework, so the application it produces only have access to what the browser has access to.

Uploading image file from VBA Excel

I know this question has been asked a lot of times already but unfortunately none of the answers have helped me. I want to upload an image file to my remote Web server (Apache). In my Excel cell, I have the file path of an image and want to use VBA to upload that file to a remote server.
I can't use any 3rd party tool in conjunction (like WinSCP), because that will make my product not very "portable-friendly". I was fine with Windows FTP, but it doesn't seems to be supporting passive mode and hence I also can't use that.
There are some threads which used IE to upload the file, and some which I believe are uploading via POST request by reading file in binary mode.
I want to replicate something similar to uploading files via HTTP POST on a website.

WebDav Pdf Saving error

I have set up a webdav folder that I can access thorugh chrome and edit files and save them back to the server, for example, I can open a word doc, edit it and save it back.
When I come to open a pdf, it wont save back to the server and downloads a copy of the pdf instead of the original.
Is there a way of enabling this to edit a pdf?
My end goal is to be able to open a pdf, add comments/highlights and save it back to the server, through my browser.
Thank you
Edit:
I have set this up through Apache 2.4, no plug ins through chrome, I have mapped a network drive to the server folder where I can open and edit files. Except PDFs, I would like to add comments to a off but when I open one the option is greyed out and when I try and save it after opening it tries to save to my desktop.
I'm not sure i've got your use case right, but if i've understood you correctly you have a link in a web page to a PDF which you're viewing in chrome. You click on that link and the PDF downloads to a temp file from which it is opened. If you edit and save those changes are simply saved to the temp file on your local PC. Is that correct?
If so, then this is simply normal behaviour for links in web pages. There is absolutely nothing in the HTML standard which suggests links should be opened by an editor with knowledge of the source location.
What you really want is for the link to launch an editor program which retrieves the remote document in edit mode (probably locking the remote resource) and then have edits saved back to the server. For this to happen there generally needs to be some special interaction in the browser. In Internet Explorer this is provided by the sharepoint dll and special script code. I think there's a plugin for Chrome which does the same thing, although differently.
I havent used the Chrome plugin, but i think this might help - https://code.google.com/p/npapi-msdocs/

Filelauncher save files

Let's say i have a list of files. When I click on one it will get downloaded and saved into the app's isostore. Then it's opened in the default viewer/editor on the windows phone like this:
Windows.System.Launcher.LaunchFileAsync(file);
But when I make some changes to the file and want to save it, it can't, because it's a read-only copy of the file. Is there some way to get write-access to the file or else some public/shared (iso)store that every app has access to? The goal is to download the file, edit it and upload it back to the server.
Per the Windows Phone documentation, the Windows.System.Launcher.LaunchFileAsync API is not implemented for the Windows Phone platform:
Windows Phone 8: This API is not implemented and will throw an
exception if called.
In regards to saving the file so that it can be accessed by other applications, this is not possible, unless the file you are dealing with is a photo, in which case you could use the Media Library API.

Transfer/Copy files from one iPad app to another iPad app for Editing

I am wondering if there is a way in objective c to have my iPad app copy a file in it's documents folder to another app's documents folder and have that app open the file for editing and finally copy the file back to my documents folder. Or better yet, can I have another app open a file from my documents folder, edit the file, and save it back to my documents folder?
So far I know I can have another app open a file in my documents folder but the app that I'm handing the document off to seems to be making a local copy and editing the copy. I also know that each app's document folder is a shared folder that users can drag and drop stuff from itunes but I'm not sure if the same can be done in code.
I am pretty sure what you are trying to do is impossible. iOS applications are "sandboxed" which means that each app has its own documents directory. No application has access to the file system outside its own "sandbox" i.e. outside its own local documents directory.
For more on the iOS application sandbox, Read here.
Though a sandbox exists, I found a way to work around it (it's a trick being used by other File Manager apps like GoAruna). I would first register my app as an app that can open the type of files that I plan to work with. Then I use the Open In functionality to have my users open up my apps local documents in the second app, an app like iAnnotate. Then, because my app is registered as an app that can open the current file type, I can instruct my users to use Open In from iAnnotate to move the modified document back to my app. Sorry but I could not accept "no" as an answer. If anyone is interested in this approach, go here
If your iPad is jail broken, try this:
On the app iFile, type in the document name in the search box located at the top. Once you find the document, click on it and options would be showed to you. From here you can choose the app you want to open the file with.
Hope this helps.