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Date: Fri, 14 Nov 2014 08:31:46 +0100
From: Milan Broz <gmazyland@gmail.com>
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Subject: Re: [dm-crypt] keys from RAM dumps, hibernation files
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To: dm-crypt@saout.de

On 11/14/2014 12:33 AM, Sven Eschenberg wrote:
> On Thu, November 13, 2014 17:35, Michael Enßlin wrote:
>> Hi,
>>
>> LuksClose _should_ wipe all remains of the key from memory.
> 
> Actually unmapping the crypto target in dm-crypt should do that. The
> luksClose operation of cryptsetup is one example that initiates unmapping.

Yes and it does it. As the same as if you use low-level "dmsetup remove".

Anyway, you can try it:
I tested it with the AES key finder (cold boot utilities)
on memory image from suspended virtual machine
(plus you need to find dmcrypt crypt structure with plain key).
After luksClose and luksSuspend all previously visible keys in RAM
must disappear.

Milan