I have some job related files I have already compressed with 7Z.
I have protected each with good 10 character passwords consisting of upper, and lower cases, numbers and special characters.
And I have enabled header encryption of the filenames.
I am not yet concerned about the physical security of my system or side channel attacks, but I have heard that GPUs are getting faster at bruteforcing even complex passwords.
Another lesser concern is that the implementation of AES in 7Z might be vulnerable.
But what if I encrypt the files with another symmetric cipher?
My theory is that such a setup keeps me secure even if an adversary succeeds in bruteforcing the outer envelope or exploits a weakness in 7Z's implementation of AES.
What's your take on the following method:
7za a -p -mhe myarchive.7z myfiles
gpg --output myarchive.pgp --symmetric myarchive.7z
I have read about meet in the middle attacks, but so far I understand the risk, it's only an issue if the adversary is able to reduce the key space by trying to decrypt key1 and key2 simultaneously.
But will this be an issue if the outer envelope doesn't give any clues as to how the next layer is encrypted?