rotating encryption sub keys

[Robert J. Hansen]

vedaal at hush.com wrote:
> to decrypt any old messages is easy, although somewhat tedious ;-)
> 
> before you destroy your encryption/decryption key,
> decrypt all the messages/files encrypted to that key,
> using the option of --show-session-key
> 
> then copy the session key as a 'comment' into the encypted message
> 
> then zip all the encrypted files with their session keys together,
> and encrypt the zip file to your new encyption key

Of course, this kind of defeats the entire purpose of perfect forward
secrecy by rotating your subkeys...