I have to define a way for two parties to exchange a folder (files) securely. Encrypted zip format seems to be the most obvious but I have read some accounts of zip encryption being flawed. So I am trying to see if there are any other solutions out there.
My requirements are -
It should be really easy (clicking the mouse and entering the key/passphrase).
Need to be free software (should not mandate the either party to buy software as much as possible)
Of course it has to be secure. If the encrypted file ends up in the wild the parties should be assured that its secure.
The cross platform nature of it comes in because some of the users involved might use a Mac.
Is my only option to use gpg? I am averse to using it but I want to see if there is any other possibility. The only problem with gpg is I will then have to define a way to exchange the public keys and verifying the public keys are properly exchanged. I am looking for a solution where one party can send the file to the other and then get on the phone and say "double click on the file and enter this passphrase".
Thanks for your help!