New DoD encryption mandate

Ivan Krstić krstic at solarsail.hcs.harvard.edu
Sun Aug 19 10:19:47 EDT 2007


On Aug 18, 2007, at 3:30 PM, Ali, Saqib wrote:

> One of the functions provided by the TPM is to wrap/bind and store the
> bulk encryption keys. Now let's us say the mother board or the TPM
> goes bad on your notebook or you simply want to upgrade the computer.
> You need to be able to restore+transfer the information stored in the
> TPM to your new computer. This is where you need TPM management suite
> that support key backup/restore and transfer.

I still don't follow. BitLocker explicitly includes a (optionally  
file-based) recovery password. If you want central management, why  
not centrally manage _that_?


Alex Alten wrote:
> Agreed, for most requirements.  Sometimes one may need to keep keys
> in trusted hardware only.

The reason the TPM is used to wrap the BitLocker key is not because  
people don't want the key to be available outside of hardware -- at  
least I've never heard of that requirement going hand in hand with  
central key backup/migrate. Instead, TPM key wrapping is used so the  
early-boot checks can be enforced. I don't see how a hardware-only  
key that you can migrate to another TPM centrally is any more secure  
than keeping a key in hardware but falling back on a centrally- 
managed spare for enabling data migration.

--
Ivan Krstić <krstic at solarsail.hcs.harvard.edu> | http://radian.org
---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at metzdowd.com



More information about the cryptography mailing list