News for hackers. Stuff that matters.

A comment on Insulin Pumps, Decapped Chips and Software Defined Radios. Parent comment

Re:Insulin Pumps, Decapped Chips and Software Defined Radios by stefan_ on Monday April 29, 2019 @09:57AM (#19778369)
The result of this diligent process, of course, is how a broken CRC16 routine got shipped in this medical product.

It's the most trivial thing. Copy a public domain CRC16 routine, add a unit test with a test vector.

[ Parent | on HN ]
Re:Insulin Pumps, Decapped Chips and Software Defined Radios by joezydeco on Monday April 29, 2019 @06:32PM (#19783229)
Can you be sure it wasn’t a badly implemented form of obsfucatiom?

It certainly slowed down the reverse engineers. If they didn’t get to the object code what would the next step have been? Cryptographic analysis?

[ Parent | on HN ]
Re:Insulin Pumps, Decapped Chips and Software Defined Radios by stefan_ on Monday April 29, 2019 @06:48PM (#19783341)
5 of the bits were never set in their "obfuscated" variant? If you want to obfuscate CRC16 you would just choose a randomized starting value.
[ Parent | on HN ]
Re:Insulin Pumps, Decapped Chips and Software Defined Radios by joezydeco on Monday April 29, 2019 @09:30PM (#19784328)
I didn't say it was implemented well. Perhaps they should changing shift operators would quietly change the values without any disturbance to checksum integrity.
[ Parent | on HN ]