[dm-crypt] Forgot dm-crypt password; suggestions on steps to undertake

Arno Wagner arno at wagner.name
Mon Nov 11 04:13:13 CET 2013

On Mon, Nov 11, 2013 at 03:25:30 CET, John Thoe wrote:
> Hello Arno and Milan

> Thanks very much for your replies. I was not successful in retrieving the
> passphrase but it was a good learning experience.  

> A question about LUKS I have is that I travel a lot and sometimes have to
> leave my laptop unattended and I put it to sleep or lock it.  Is it
> possible for an attacker to retrieve the keys while the laptop is in that
> state.  My question is that should I always shutdown the laptop to be safe
> or is it fine to leave it locked or in sleep mode?  Can the keys be
> recovered from memory?

The keys can be recovered from memory. Also, an attacker could
boot your machine and install malware or could install a physical
key-logger. The usual consent is that if an attacker has 
repeated unnoticed physical access to a machine, no security 
measure will help. Even encryption (shut-down state) will really
only help against an attacker that gets access only once and
steals the machine.

Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno at wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
There are two ways of constructing a software design: One way is to make it
so simple that there are obviously no deficiencies, and the other way is to
make it so complicated that there are no obvious deficiencies. The first
method is far more difficult.  --Tony Hoare

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