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I have been asked by a relative to encrypt both a USB pen & a Hard-disk folder. My immediate thaught was to use Truecrypt being that its free and relativly decent!

My question is this: is there a way to enter the decryption-password and decrypt both the pen AND the hard-drive volume at the same time? Obviously the solution should hopefully work if the USB Pen is not present or the USB pen is being used in a seperate computer.

Having not used Truecrypt before in anger I would be grateful for any assisstance.

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1 Answer 1

up vote 5 down vote accepted

TrueCrypt has an option to cache the encryption password. If you check it when entering the first password, TrueCrypt will try to use it for future volumes.

For example, my login script looks kinda like this: (converted from Python)

truecrypt /volume foo.tc /letter p /auto /quit /cache y
truecrypt /volume bar.tc /letter q /auto /quit
truecrypt /wipecache /silent /quit background
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Wouldn't this be unsafe (kinda loosing the advantage of the password in the first place)? I trust TrueCrypt to not give unsafe options, so there must be more to this... –  nik Oct 9 '09 at 12:02
    
The cache is only stored in memory, and in my example wiped at the end, using /wipecache –  grawity Oct 9 '09 at 12:42
    
Of course, "only stored in memory" really means "only stored in memory and maybe also in the paging file/swap area". Once the data hits disk, there are advanced forensic tools available to certain classes of adversaries that can recover old bits even after they have been overwritten by newer values. You can mitigate against this by disabling your paging file/swap area. –  Fran May 3 '12 at 17:08
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@Fran: Modern operating systems allow a program to mark certain memory areas as unpageable/unswappable. (In the case of TrueCrypt, the cache is kept by TrueCrypt driver.) –  grawity May 3 '12 at 17:09
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@grawity Yes, but the TrueCrypt passphrase is read by its GUI in user-space and then transferred into the kernel for use by the driver. No matter how quickly the user-space code erases the passphrase from RAM, it may still end up in the paging file/swap area. –  Fran May 4 '12 at 16:10

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