Two keys for the same encrypted file

[kinto <kintho@xxxxxxxxx>]

Hi all, I've a question for you.
This is how I encrypt a file:

head -c 2925 /dev/random | uuencode -m - | head -n 66 | tail -n 65 \
        | gpg --symmetric -a >/tmp/keyfile.gpg


dd if=/dev/zero of=/tmp/file.img bs=1M count=10


head -c 15 /dev/urandom | uuencode -m - | head -n 2 | tail -n 1 \
        | losetup -e AES256 -K /tmp/keyfile.gpg /dev/loop1 /tmp/file.img


mkfs.ext2 /dev/loop1

mount /dev/loop1 /mnt/crypt

(This is my complete procedure, please check it out :) )


I want to use two different keys for encryption the single file, but one 
key must be have a time-limit validity.
Is it possibile?
Thanks in advance for the help.

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Linux-crypto:  cryptography in and on the Linux system
Archive:       http://mail.nl.linux.org/linux-crypto/