Would this be incorrect?

[Juf]

After my buisness and IT teacher told me that when powering off a computer the RAM 'dissappears'. Then I recalled the cold-boot attack series and I'm wondering, would this phrase be incorrect?

RAM data disappears when you turn off the computer.

I presume it is but just want to make sure.

Thanks in advance,

Juf

[Sparda]

RAM chips lose there data after a few seconds after losing power. In some cases it is possible for the data in the RAM can be maintained by ensuring the motherboard has power (not necessarily switch on however), this is motherboard dependant however.

[Juf]

RAM chips lose there data after a few seconds after losing power. In some cases it is possible for the data in the RAM can be maintained by ensuring the motherboard has power (not necessarily switch on however), this is motherboard dependant however.

If I were to apply a coldboot attack against program data, not for examole saved texts files. Would I potentially be able to restore that state if I were to restore power within milleseconds? My teacher does'nt understands the coldboot attack and she wants to apply it to program data.

[dallaskorben]

The time that RAM will hold data without power can be affected by a few factors. Some variables may include the type of memory and temperature. The 'data remanence' article on Wikipedia has a very brief description.

I haven't done any experiments with DRAM in a PC, so I don't know firsthand how long data might last and under what circumstances. I have experimented a little bit with SRAM (in my case a smaller capacity chip used with a microcontroller) and in some cases data can last for a while (even seconds), though as time goes on more and more bits become corrupted. Cooling the chip can make a big difference - Sergei Skorobogatov published a paper about some experiments he did with cooling SRAM chips to retain their data (footnote #7 on the wikipedia article is a link to Skorobogatov's paper - http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-536.html)

DRAM will have different characteristics than SRAM - the DRAM should have much shorter retention time because it has to be frequently refreshed - but I have no idea of actual numbers.

If you do some experiments with this, it would be interesting if you recorded and posted your results!