Let's say I have access to multiple computers at several locations, and at least one is secure. I encrypt the plain text on c1, put on a USB key, encrypt the encrypted file again on c2. Then again. Then transfer the file to a new USB key and destroy the original (in case file system there has remnants of other files).
The adversary would have to know all three passwords to decrypt the final file.gpg.gpg.gpg, correct?
