Re: Tramp and crypted files

[Deus Max <deusmax@gmx.com>]

On Fri, May 29 2020, Michael Albinus wrote:

> Deus Max <deusmax@gmx.com> writes:
>
>> EncFs adds file name encryption and obsfucation, making in hard to guess
>> the encrypted file, even if you know the file name. So you have to
>> temporarily mount somewhere, in order to see the decrypted filenames.
>
> No. The new tramp-crypt file name handler makes this transparent to
> you. Given, you have declared "/nextcloud:host:/crypted/" as crypted
> remote directory. If you call for example
>
> (directory-file "/nextcloud:host:/crypted/subdir")
>
> this file name handler will transform "/nextcloud:host:/crypted/subdir"
> to "/nextcloud:host:/crypted/XXX", in case you have created a
> subdirectory "subdir" and it has the name "XXX" on the nextcloud
> server. Then the vanilla Tramp command is called as
>
> (directory-file "/nextcloud:host:/crypted/XXX")
>
> using the encrypted file name. It returns the list ("." ".." "YYY" "ZZZ"),
> with "YYY" and "ZZZ" being encrypted file names on the server. This
> result is received by the file name handler, and it transforms this list
> to ("." ".." "foo" "bar"), with "foo" and "bar" being the plain text
> file names of "YYY" and "ZZZ". So, finally you see
>
> (directory-file "/nextcloud:host:/crypted/subdir")
> => ("." ".." "foo" "bar")
>
> without even thinking about that this is a crypted remote
> directory. Same scenario for all other magic primitives, which are
> implemented by Tramp.
>
Great! I  need to reed up on the new tramp-crypt handler.

>> Yes, the .encfs6.xml is very importantf for EncFS.
>> I think encfs needs a temprorary mount point, to function. This can be a
>> weakness in a network situation, as any interruption could leave the
>> files open or in a strange state, inviting the case to be compromised.
>
> No. An encfs mount point is needed only in case you create a new
> .encfs6.xml file. Tramp would do this transparently by calling "encfs
> tmpdir1 tmpdir2". Then it saves tmpdir1/.encfs6.xml, unmounts the encfs
> mountpoint, and removes the temporary directories.
>
True. Thanks for correcting that.

DeusM