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Help Me Understand The Cryptomater Process Please!

So, I want to encrypt my files with Cryptomater before they go to my cloud based backup service. Lets say I use Dropbox.

So I know I create a Cryptomater vault and give the location as a folder in Dropbox.

I can't see that Vault until I open it in Cryptomater, right? This means I can't add anything to that Vault unless its open on my machine. As its open, I'm assuming that the data I'm adding is unencrypted until I close the Vault?

Lets say I add a plain text file to an open Vault.

So, at what point does Dropbox upload that file? Is it the minute its added to the Dropbox environment? Because that would mean its unencrypted.

Or is it not uploaded until the moment the Cryptomater vault is closed? Because that would mean I'd either have to leave the Vault open the entire time I was on my device and possibly have to do one (potentially) big upload at the end of the day maybe or keep opening and closing the Vault every time I wanted to work with the Vault (edit an existing document, add a new one, delete one etc).

Or have I misunderstood the process? I hope so because it either sounds not very secure or not very usable.

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  • at what point does Dropbox upload that file

    You can't know that because it is closed-source but it's irrelevant because the files are encrypted already. Cryptomator is fun because each file has its name and content encrypted separately which means that you only need to upload what changed, compared to Veracrypt that has to send everything every time. I guess Dropbox is smart enough to notice small changes and send them immediately. As a comparison, OneDrive (by Microsoft) is full of bugs and is sometimes stuck and won't sync for days unless you fix the broken mess with a specific obscure command.

    Is it the minute its added to the Dropbox environment

    The file is never added to Dropbox. It is added to the virtual drive of Cryptomator which encrypts everything before saving it. Then Dropbox can see that a change has happened in that file (that is encrypted but it's irrelevant to Dropbox) and it is sent whenever Dropbox wants to.

    Because that would mean its unencrypted

    It's like: open Cryptomator as fake drive -> drag and drop file -> it is encrypted and then saved -> Dropbox sees change -> encrypted file is sent. The file is encrypted in memory before reaching the hard drive. Storing it before would be a huge security bug.

    that would mean I’d either have to leave the Vault open

    I know it's a privacy community, but what's wrong with leaving the vault open in the background? On the phone the application can be protected with a PIN or a fingerprint, and on your desktop you can have a hard drive encrypted locally and a user password. It never crossed my mind to close such "small" vaults because it's only for a small number of files that you use daily. You must never rely on solutions such as Dropbox to store all your files forever.

    And for the record, I do trust Cryptomator because they make Cyberduck and their code is open-source, and also because you can support them by buying a license which is useful for them to keep on working on that. In the past few years, I have never read bad things about them.

    it either sounds not very secure or not very usable

    It is secure because it basically encrypts AND THEN store that in a tree of files, nothing else, and so far they do it well. No plaintext file is stored. It is usable for what it is: synchronization of a lot of small files which expects that the vault stays open, but most people do that anyway, it's still secure as long as you don't give your phone to strangers.

    If you need a stronger solution, use Veracrypt but you will lose the ability to use it easily and fast, and the whole blob (multiple gigabytes for me) will have to be copied every time you need to sync anything. Both usages are legitimate.

7 comments