Lucky Green wrote :
It is true that methods exist to recover data from RAM even after it has been "erased". First and foremost, there are physical processes taking place in the substrate that cause permanent changes in the cells containing the data. In general, if there is a chip left to analyze, the data that used to be stored within can be obtained. [The particular opponent may of course choose not to spend the funds required to perform the analysis.]
The only way to reliably remove data from RAM is to destroy the substrate. I recently investigated various methods of doing so for a certain high security application. My research showed that the only portable (and truly reliable) solution for this task are micro explosives. Perhaps unsurprisingly, the US uses explosives to protect the electronics in nuclear weapons. The local ATF office informed me that any device using explosives to destroy its contents would be considered a booby trap, even if the explosion would be contained to the inside of device and therefore not pose a danger to the operator.
I have heard about thermite devices being used for this in the sort of applications that might warrent it. Granted that this is a royal fire hazard unless very carefully engineered, but at least it is not an explosive per se.... One can reduce this effect somewhat by implementing software or hardware methods that complement the key or whatever you are protecting every few seconds. But I can testify, as someone who has done hardware design, that the memory effect is real and very pronounced... not a myth. Dave Emery die@die.com