A83: Ti Certificates
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A83: Ti Certificates
If you care to look at the TI-83+ SDK, the certificate area (i.e. page 1E)
contains 2 public keys, which does insinuate TI's using RSA cryptology. But
for MD5 fingerprinting, I'm not really that convinced, the algorithm is
composed of 4 steps and uses some precalculated sinus tables and 16 words
(32 bytes) are processed at once. Fingerprinting 507904 bytes should take
far longer than ten seconds. Also MD5 produces 128 bit fingerprints,
application headers are slightly larger even if that's influenced by the RSA
crypting.
Also, you must have noticed that on link error while installing base code
you get the following message:
ERROR!
Press any key to turn unit off.
Then turn unit
back on.
Well, the SDK says that the boot area is unalterable but if you just care to
look at a compiled base code file (VTI *.ROM or TI debugger *.clc), you'll
find that piece of code, with lots of luck maybe the algorithm is coded
there.
Links related to MD5:
the algorithm - rfc1321
(http://www.cis.ohio-state.edu/htbin/rfc/rfc1321.html)
MD5 performances - rfc1810
(http://www.cis.ohio-state.edu/htbin/rfc/rfc1810.html)
Solignac Julien
x1cygnus@xcalc.org
http://xcalc.org
Piracy is a victimless crime, like punching someone in the dark