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I'm aware that the plaintext password is used to decrypt the header which stores all the decryption details for the actual data.

So there is no reason to store the actual password in memory once the decrypted header is copied into there.

So my question is:

  • Assume an attacker has access to your PC while a TrueCrypt volume is mounted.
  • Assume the attacker has the ability to dump driver memory.
  • No keyfiles are used.

Will the attacker be able to recover the password you entered? Or will he only be able to recover the decrypted header?

A higher level of this question would be: Will the attacker be able to compromise other unmounted encrypted volumes that use the same password as the mounted one?

  • Assume no other unrelated weaknesses of any sort.

Edit: I'm NOT talking about the cipher key(s) stored inside the header. I'm talking about the password that gets salted and hashed to decrypt the header itself.

3 Answers 3

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NO. it does store the cipher-key however which is just as bad if not worse, and yes there are several "password recovery" tools that will scrape ram, your pagefile, and your hiberfil.sys to find the key.

Also, no it is my understanding that your key is somewhat randomized based on your password input, such that the same password will result in different keys. see more info here: http://www.truecrypt.org/docs/header-key-derivation

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  • Your answer seems to be the only one to address my question. How certain of this are you? And yes I know that the actual cipher keys have nothing to do with your password, they are random. Oct 29, 2013 at 20:17
  • I would normally say 'yes I am sure', but the first lesson in crypto is don't try to roll your own, because this stuff is too complicated for amateurs (which I am). Their use of a 512-bit random salt and PBKDF2 should result in widely different keys, but no one I know could confirm that beyond a common-knowledge level of surety. Oct 29, 2013 at 20:27
  • Seeing as I'm running into a related problem, can you refer me to any of these password recovery tools that'll scrape my running OS RAM to find the key and/or password?
    – qasdfdsaq
    Jan 16, 2019 at 22:20
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As long as the volume is mounted, then the key is sitting in RAM.

From TrueCrypt's site: Unencrypted Data in RAM.

Inherently, unencrypted master keys have to be stored in RAM too. When a non-system TrueCrypt volume is dismounted, TrueCrypt erases its master keys (stored in RAM). When the computer is cleanly restarted (or cleanly shut down), all non-system TrueCrypt volumes are automatically dismounted and, thus, all master keys stored in RAM are erased by the TrueCrypt driver (except master keys for system partitions/drives — see below).

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There was a famous experiment where a university had someone log in and then shut down and then froze the memory of the computer. They then removed the RAM and read it from another system so the attack is theoretically possible. The password was still in RAM. Can't remember if this was for Truecrypt specifically or not, but I believe so. Not sure if more recent versions of Truecrypt tried to wipe the memory of the password or not. More disturbing is the possibility of doing this through a DMA priviledged port. If I remember right, ports like PCMCIA and one particular Mac port had direct DMA access so you could just plug a card in and it could suck the contents of RAM down with no interaction necessary.

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  • No need to bother shutting it down, you just hotswap it onto a UPS and cart it off running. Image memory and drive and play away. Oct 29, 2013 at 20:24
  • Part of the experiment was the question of how long it takes for bits in memory to randomize once the power was removed. Oct 29, 2013 at 20:26
  • The freezing is dicey, the hot swap is here and now and regularly used. George could have saved his Frogger score without the hilarity. Oct 29, 2013 at 23:01

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