Add note about SSE

[juliushaertl]

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[codecov]

Codecov Report

Merging #231 (bb259e2) into master (5ad5843) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #231   +/-   ##
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  Coverage     83.78%   83.78%           
  Complexity      328      328           
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  Files            30       30           
  Lines           925      925           
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  Hits            775      775           
  Misses          150      150           

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php	83.78% <ø> (ø)	328.00 <ø> (ø)

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[robolange]

@rullzer Can you explain what this means? What is incompatible? What is the consequence of running both modules simultaneously? I currently have a test system running NC 21.0.1 with server side encryption (default module) and End-to-End Encryption and everything seems to work correctly. I can see that on the server, the E2EE encrypted files are also encrypted with the server-side module, but they are still named using hashes instead of file names, as when using E2EE alone. If I do not enter the correct E2EE mnemonic on a new client, I cannot see those files. If I do enter the correct mnemonic and resync, then I am able to view the E2EE encrypted files.

My biggest fear when both modules are enabled is that the files are somehow encrypted using only the server side key. But, I can't figure out how this could be the case, because the files should already be encrypted before being sent to the server. I would like to answer this question definitively by manually decrypting a few of these files using the server-side key, to verify that they are indeed still encrypted with the E2EE key as well. Any pointers you have on doing this would be appreciated.

So I guess what I'm asking, is why are these modules considered incompatible? Server-side encryption may be somewhat redundant when E2EE is enabled, but at least with my current testing, they appear to work together properly.

[juliushaertl]

The main issue here is that both encryption modules make use of the encrypted column of the filecache so there might be unexpected behaviour due to that and currently this is neither tested nor supported.