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The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:28 ADT
Mark Tillotson (markt@harlequin.co.uk)
Thu, 16 Jul 1998 17:19:26 +0100
| Oskar Pearson writes:
| > [ RAM burnin ]
| >
| > What if we were to simply reverse all ON bits with OFF bits
| > periodically? Very straight forward to do, and since the time periods
| > of on and off would be equal, there shouldn't be a problem... right?
| > we would just have to keep a single bit that said 'we are in the
| > original state' or 'we are not in the original state - xor before
| > using'.
| >
| Why not use a second buffer containing the inverted key and exchange
| the contents every so often?
|
| Any comments?
This RAM-burn-in effect is mentioned in Peter Gutmanns paper
"Secure Deletion of Data from Magnetic and Solid-State Memory"
There might well be a second-order effect, in which case swapping two
inverted copies might not be good enough, if you can determine the XOR
of neighbouring key bits...
Basically ions diffuse through the SiO2 in response to the powerful
electric fields across the gate...
Probably best to move the key around a block reasonably frequently,
rewriting the whole of the rest of the block with (pseudo) random
junk.
__Mark
[ markt@harlequin.co.uk | http://www.harlequin.co.uk/ | +44(0)1954 785433 ]
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:28 ADT