On Thu, Jul 10, 2003 at 04:45:58PM +0200, Thomas Shaddack wrote: > On Wed, 9 Jul 2003, Eric Murray wrote: > > I doubt it as well. DRAM also has power-off memory persistence > > and nearly everyone in security ignores that as well. > > > > But not the spooks : > > > > "The FEI-374i-DRS is a data recovery system that captures and preserved > > digital data, in its original format, directly from the Dynamic Random > > Access Memory (DRAM) of Digital Telephone Answering Machines (DTAMs) > > .. > > The FEI-374i-DRS is an indispensable tool for forensic investigators > > required to evaluate residual audio and tag information retained in > > today's DRAM-based DTAMs." > > > > http://www.nomadics.com/374idrs.htm > > The system doesn't seem to be able to recover data from powered-off DRAM.
[..] It's still interesting. > It is impossible to get access to the voltage on the DRAM cell capacitors > (at least if the chip is in its case and we can access only its pins). We > can only see if it is in the range for H or L. And after a power-down (or > even a sufficiently long period without a refresh of the given cell) the > cell capacitor loses voltage steadily, reaching the level of L (or maybe > H?) within at most couple seconds. I would not bet on that for sensitive data. See Peter Gutmans and Ross Anderson's papers on RAM memory remanance. Eric
