A89: rom checksum
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A89: rom checksum
The calculator uses MD5 to compute the ROM checksum when it recieves a
ROM, right?
The general opinion is that it uses RSA, but has TI verified this?
There -are- MD5 romcalls, though...
Well... MD5 is not a public/private key algorythm.
MD5 is a hashing algorythm.
With a single key. (Not public/private)
Guess what that means...
s
p
o
i
l
e
r
s
p
a
c
e
It means the key is in the ROM already!
You just have to step through it, find the routine in the boot loader
that does the actual MD5 hashing, and the key will be there too!
Hehe, this means free app signing... ;)
A bit for the crypto nuts:
MD5 produces a 128bit checksum, whereas the 89 is rumored to have a 512
bit one.
Well, what's to stop TI from having FOUR 128bit checksums? That comes
out to 512.
Sneaky, eh?
Well, i'll be off to go look for code which resembles MD5.
Anybody who wants to join, feel free!
--robin
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