CODEWITHSUNDEEP
digital-signatureapdu
Igor Aleksic
Igor Aleksic

Reputation: 11

Tachograph smart card .ddd file signature

I have made android app that reads truck driver card (from tachograph) via otg smart card reader. I can read all files on card from tree structure on image bellow.

structure

But when I compare data that I read, and from some other public application, I have noticed that some files are fallowed by something that might be a key or signature signiture

I do not know what underlined part represents nor how to read or generate it.

Without those "signatures" all data that I have is useless, but if I hard code those underlined parts (from other apps) in my ddd file, everything works fine

The most I have found is that 05 04 - Current usage Data 01 - means there is still a signature (gen 1) 00 80 - 0x0080 = 128 dec

Also I have read card certificate and ca certificate from card but didn't find is there any correlation with underlined part of problem.

Upvotes: 0

Views: 1224

Answers (1)

Igor Aleksic
Igor Aleksic

Reputation: 11

Thanks to @nvf I found explication and solution in document

Part of responses .ddd that start with "01 00 80" represent digital signature of hash value on previously selected file. To get digital signature you should select file, execute command to perform hash of file, and then execute command to get 128 bytes digital signature.

Upvotes: 1

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