On Sun, May 1, 2022 at 3:07 PM David Laight <[email protected]> wrote: > Using the same file twice is better than having nothing at all. > At least different systems use different values. > Unless you have a remote 'dos' attack that can crash the system > at exactly the right point in the boot sequence this is an > entirely 'academic' error. > > What is much more likely is that the file where the entropy > is saved is just a memory overlay on top of a read-only image. > > That is much more likely for an embedded system than any of > the 'failure' cases you've considered. > > I also wonder how sane it is to do 'new_key = f(old_key)'. > That doesn't seem significantly better than using the same key. > > For a really embedded system the only persistent storage > could easily be a small serial EEPROM with a very limited > number of write cycles. > This requires special code to read/write and care to avoid > hitting the write cycle count on a small number of memory cells. > No amount of faffing about with filesystem accesses will > help here at all.
Exactly why I want to hear about real-world cases where it was demonstrably difficult to initialize RNG properly. Need to separate fiction and exaggerations from reality. > There is also the case (that on my systems at least) udev > initialisation reads from /dev/[u]random well before the S20 > script loads any saved entropy. > I've not tried to find out what the value is used for. _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
