[LINK] Stolen Laptop [was Re: Consumer computer security]

Rick Welykochy rick at praxis.com.au
Mon Jan 29 11:33:42 AEDT 2007

Rick Welykochy wrote:

> There is the kicker, in the last result. Note that Johann did not
> notice the AES encryption with normal usage, and the above results
> back that up. The encryption overhead for short copies is overshadowed
> by normal kernel overheads. But when you start doing some Real Work
> on the machine, it can bog down to 1/2 or less of normal throughput.
> That is my consistent finding.

Might I add here that if the entire C: drive is AES encrypted
on Windows, then the entire system is bound to run slower,
perhaps even at 1/2 speed where disk access is concerned, when heavy
loads are applied to the system. This is because when you
run an application, the app is read from an encrypted file system
and then paged into memory in a re-encrypted form. As well,
all the application data is encrypted and thus must be decrypted
as well. I'll stop harping on about the speed penalty, but
trust me. It is there.

Far better to encrypt just the home directories.

As well, since there are GB of known plain text on a Windows
Vista system, having all that plain text available in a form that
is encrypted using your precious secret key is just asking for
trouble. This is because the more encrypted known plain text
you have, the easier it is to break the cipher.


Rick Welykochy || Praxis Services

People who enjoy eating sausage and obey the law should not watch either being made.
      -- Otto von Bismarck

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