To modify encrypted data on hard disk partition means that attacker has to root the box first. If attacker successfully roots a box, it is "game over" securitywise right there. Only sane option after that is reinstallation and/or restore from known good backup.
well it is a valid argument if you assume the OS has been corrupted.
Nevertheless this assumption isnt mandatory, here is a scenario where it doesnt apply:
1. a user encrypt a whole removable disk with loop-aes
2. he goes in a conference and leave it unattended in a room (bad
practice but it happen)
3. an attacker gets it, insert chosen data in it and put it back
4. the user replugs the removable device
=> with the current loop-aes, the attack succeed
o the modification goes undetected and the user uses attacker's data
as if they were legitimate.
=> with a loop-aes patched with authentication, the attack fails
o it is detected by the authentication and the user can act
appropriatlymy point is to make people aware of the security limit offered by the tool they use. After, they can do the knowledgeable decision to use them or not, depending on their own requirements. Thus they dont loose/leak important informations because they were not aware of those limits.
- Linux-crypto: cryptography in and on the Linux system Archive: http://mail.nl.linux.org/linux-crypto/
