#1 Verification in Tachograph signatures

[Rik Oostveen]

Hello Readesm team. Let me start of by thanking you for making this marvelous piece of freeware. I was wondering if you could help me - I'm trying to recreate a program with similair functionality in Oracle's PL/SQL, that reads each file on download. I don't have a single clue, however, on how to verify the signatures of the blocks. Could any of you tell me how I extract the key, and how I use that key to verify blocks? I have the MSC SIGN, the MSC CNDASH, the VU SIGN, and the VU CNDASH, but how do I find the key in it? I intepreted from the documentation that the signatures are SHA1 Hashes, however, those hashes should be 20 bits, not 128. Could anyone explain this to me in laymans terms, as I don't understand the documentation. I am quitte new on Cryptogtaphy, and only know basics. Thanks in advance.