topic Re: S32K CSEC MAC Generation in S32K

S32K CSEC MAC Generation

wanglijun — Tue, 09 Nov 2021 02:48:00 GMT

Hello,

I have a question about the CSEC MAC generation: Is the result same for copy method and pointer method?

Thank you!

Re: S32K CSEC MAC Generation

lukaszadrapa — Tue, 09 Nov 2021 16:11:49 GMT

Hi,

yes, you should get the same result.

Regards,

Lukas

Re: S32K CSEC MAC Generation

wanglijun — Wed, 10 Nov 2021 00:30:35 GMT

Hello Lukas,

The following 2 picture is for the copy method and pointer method:

(1) Copy method:

(2) Pointer method

I found the MAC generation is different. Can you help check the reson? Is it becasue little endian or big endian?

Thank you!

Best Regards,

Wang Lijun

Re: S32K CSEC MAC Generation

lukaszadrapa — Wed, 10 Nov 2021 10:55:20 GMT

Hi Wang,

there's only one corner case when CSEC_DRV_GenerateMAC doesn't work as expected - when the size is a multiple of 256KB. This limitation will be published in next errata release.

But if you use size different from n*256KB, it works as expected.

CSEC_DRV_GenerateMACAddrMode does not have this limitation.

I tested it in the past and I got the same results when calling:

error_code = CSEC_DRV_GenerateMACAddrMode(CSEC_RAM_KEY, 0x50000, size, cmacAddrMode);
error_code = CSEC_DRV_GenerateMAC(CSEC_RAM_KEY, 0x50000, size, cmac, 1000);

Regards,

Lukas