The nis-ncc-0.6.91.zip.sig file should contain the block height where a transaction was included and the transaction hash. With that info it was  possible to go to nembex and display the transaction. The transaction has a hex message, where I had to remove the first 4 bytes (8 chars) to get the sha256 hash of the zip file. This procedure worked for nis-ncc-0.6.87.zip. But WTF is going on with the latest version?

Can anyone tell me please how to get the right hash ?

And what crazy dude did invent such stupid procedure that doesn't work anymore ?