Release: gpg (GnuPG) 1.2.1
Environment
Red Hat Linux 9.0
Description
Decrypting a file that's been encrypted with "gpg -c" (symmetric encryption with a passphrase) prints a warning message after decrypting: "gpg: WARNING: message was not integrity protected".
Properly designed symmetric encryption should always include a MAC keyed on the encryption passphrase, appended to the ciphertext. That serves as an integrity check in that it shows that whoever encrypted the file had the secret key.
There's two possibilities:
- gpg -c includes a MAC and therefore this warning message is spurious; the fix is to remove it.
- gpg -c doesn't include a MAC and therefore isn't well designed. Some kind of extension should be developed that adds a MAC that does NOT depend on a stored private key on a key ring. Preferably, the extension can be designed so that ciphertexts with the MAC will still decrypt with old versions of gpg, even if the old versions don't check the MAC. That would allow the extension to be enabled by default in new versions. However, that may not be possible.
Either way, some type of fix is adviseable.
Fix
Unknown