how to do a digest on a flashed uImage ?

Philippe Leduc ledphilippe at
Wed Jul 1 00:02:28 PDT 2015


I have a uImage saved in a memory partition and I am able to boot on
it with bootm command. I would like to add a digest (like a
hmac(sha1)) in order to check the integrity of the binary before
booting on it.

Because my partition is bigger than my uImage, I don't know how to use
digest on it.
In fact there are two problems that I don't know how to solve: I can't
get the size of my file and I can't ask digest to work on COUNT bytes.

For the size problem: I can extract the size of the uImage in binary
form since this information is present in the uImage header (via
memcpy), but I don't know how to convert it in a format compatible
with Hush.

For digest, I can copy the binary in the RAM, but I fear that it is
longer than working on the flash: it takes 4,8s to memcpy the uImage
in a RAM file, and less than 3s to bootm on the flash. But

Do you know a way to get the size of a file? Or to convert a binary
size into a "human readable format" for Hush? Or should I develop a
kind of "stat" utility for barebox?
Thank you in advance,

I hope my explanation is not too convoluted :)

Thank you in advance,

Best regards,

Philippe LEDUC
ledphilippe at

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