Hi, is there anyone here who uses the Auth and AuthCompute Commands? If so, then please describe me the procedure of Inbound Only Authentication.
I use Auth in Mutual Authentication mode, which is basically inbound + outbound and it works OK.
I don't use AuthCompute though as I evaluate the MAC myself in C as described in the datasheet in sections I.3 & I.6
What response code error do you get
ERROR CODE 0x40 (Bad MAC), can you share your code to calculate MAC?
Sadly it's not my code, it belongs to work, so I'm afraid I can't let you have a copy.
I can tell you a few of the 'gotchas' I stumbled over writing it...
The mac_flag byte in the ADATA block. Make sure the Random bit and the Input bit are set correctly for your MAC.
Check the endian-ness of all your parameters, and the length fields in the A_0 and B_0 blocks.
Using a constant nonce makes things much easier and will ensure MacCount=1 for the InMAC calculation used in the Auth command immediately after (re)loading the nonce.
Auth was the first command I got working because it has no payload and so is the simplest MAC calculation, thoug it still took a week of fiddling to get it going.
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