RE: encrypting swap

[Anders M Montonen <ammonton@cc.helsinki.fi>]

On Thu, 17 Aug 2000, Strohm Thomas (FV/SLD) * wrote:

> 1) You switch the laptop completely off (no suspend to disk!). Then 
> there may remain sensitive data on the swap partition.
> Solution: Just overwrite the swap partition with zeroes on shutdown:
> 	swapoff, then dd in=/dev/null out=/dev/hda<whatever> ...

The problem with this method is that with suitable equipment, reading a
drive wiped in this way is pretty easy. A better way would be to write
random data over the drive, but to be sure you have to do it several times
(I believe there is an american directive regarding this that requires you
to write random data six times). This is time-consuming and even then 
might not be completely safe.
 On the other hand, encrypting the swap ensures that whatever data can be
read is useless. Yes, there is a performance hit, but if you need this
level of security it is the price you have to pay.

-anders


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