Not so long ago, I was chatting with a friend on our university's accounts, and the discussion went to an interesting subject: what if the administrators have access to our messages?
So we had the idea to encrypt
.txt files using some software (
7zip for example) and send these files through hangouts securely.
An idea would be to encrypt the file with my key then send it, my friend would encrypt it with his key then send it back to me, I decrypt the file with my key then send it back to my friend who would finally be able to read the contents of the file. The problem here is that the order of encryption keys matters for 7zip's encryption algorithm, so step 3 would fail, because only the last used key can be used for decryption.
So, is there a workaround? (pretty sure there is, cryptography does magic), and is there some simple utility to do such a thing maybe without manually bothering about the details?