I have used the following command to symmetrically encrypt different files, all with the same passphrase:
$ gpg -c --s2k-cipher-algo AES256 --s2k-digest-algo SHA512 --s2k-count 65536 some_file.txt
The use case is that these encrypted files are never shared, and only meant to be decrypted on my machine. I am using
gpg-agent to cache passphrases for a certain time duration.
First question; am I correct that
gpg-agent caches passphrases per encrypted file? In other words, it seems caching of the passphrase by
gpg-agent works, but only per file, not per passphrase?
To be able to use the same passphrase for encrypting multiple files, without having to re-enter the same passphrase multiple times initially, I now encrypt a single passphrase file, and then use
$ gpg -d ~/.key.gpg | gpg -q -d --batch --passphrase-fd 0 ...
for every encrypted file to ensure I only need to enter the passphrase once per session. Any issues with this approach except for the fact that only one passphrase is used?