Someone proposed that one could wipe the memory before power-down, for example during 1 second or something like that. Unfortunately, that wont help, unless I misread the paper. It is effectively the same as if the key had been stored in the cell for 1 second less, nothing else. The only way I can see how to avoid generating "imprints" of more or less static data is to make them non-static. Start circulating them around. One way that springs to mind for keys are to do something like inverting the meaning of the key every x milliseconds. Like this; /* pseudo code */ char master_key[KEYSIZE]; int meaning = ZEROS; void encryption(char *input, char *output); /* implicit master_key */ int using_key = FALSE; main() { input_from_keyboard(master_key); timer(100 ms, flipem()); /* calls flipem every 20 ms */ main_loop(); /* occansionally using encryption() */ } void flipem() { if (using_key) /* risk of never being able to flipem() */ return; /* some kind of semaphored section */ using_key = TRUE; master_key = inverse(master_key); meaning = (!meaning); using_key = FALSE; } void encryption(char *input, char *output) { char real_key[KEYSIZE]; /* must be on stack */ copy_key(real_key, master_key); if (meaning == ONES) invert(real_key); /* recovering real content */ encrypt(input, output, real_key); write_random_key(real_key); /* so "real" key doesn't become imprinted as well. */ } Do don't care about the plaintext in the above. Nor stack content vrey much. Nor about coding style.