Is it your AES-CMAC engine is working properly. I'm unable compare the output generated by your engine and other 3rd party engine.

Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

cross mob
srko_2574741
Level 1
Level 1

Hi dear Cypress,

Please, let me know about this.

Thanks

0 Likes
10 Replies
Yugandhar
Moderator
Moderator
Moderator
500 solutions authored 1000 replies posted 5 likes given

Hello,

Could you please explain more on what exactly you are doing? Can you please share your project.

Thanks,

P Yugandhar.

0 Likes

Hi Yugandhar,

I'm using CySmart 1.2 IDE after connecting CySmart as a master to the other 3rd party(Peripheral).

I am using singed write command from the IDE  to send a one byte data. I'm facing the issue with generated signature.

It is not matching with the 3rd party generated signature. Can you please help to resolve the issue or am i doing something wrong?.

Thanks,

Srinivasareddy

0 Likes

Hello Srinivasareddy,

Can you please share your Cysmart log keys?

Thanks,

P Yugandhar.

0 Likes

Hi Yugandhar,

please find the keys below;

LTK :D6:93:E8:A4:23:55:48:99:1D:77:61:E6:63:2B:10:8E

IRK: 0A:2D:F4:65:E3:BD:7B:49:1E:B4:C0:95:95:13:46:73

CSRK: 90:D5:06:95:92:ED:91:D7:A8:9E:2C:DC:4A:93:5B:F9

i'm using CSRK and one byte data (ex : 0x52)  to send the signed command .

check below attached image for clear details.

Thanks,

srinivasareddy.cysmart.png

0 Likes

Hello Srinivasareddy,

In the Cysmart, please save the logs as shown in attached image and share that saved document.

Thanks,

P Yugandhar.

0 Likes

Hi yugandhar,

Please find the log in the attachment.

Thanks,

Srinivasareddy

0 Likes

Hi Yugandhar,

Is there any update?.

Thanks,

Srinivasareddy

0 Likes

Hello Srinivasareddy,

In the peripheral device, can you please read the peer device keys and check whether the stored keys are same or not.

Please check with same security levels and security mode 2 in both central and peripheral device.

Thanks,

P Yugandhar.

0 Likes

Hi Yugandhar,

Thanks for your reply,

I have verified the keys on both the sides and are matching exactly and am using the same security level i.e : mode 2.

Still i am facing the same issue as mentioned in the 1st query?.

For got about the test case.

My intention is that the generated signature output (1st or last 8 bytes key in the signature)should match with the Other 3rd party AES-CMAC engine output.

Can you please confirm me, weather the output generated from the cypress AES-CMAC is matching with the output given by the Bluettoth Spec 5.0 when given the same input key and sign-counter value mentioned in the Bluetooth Spec 5.0 : Vol 3: Part F : 3.4.5.4 signed write command.

waiting for your valuable reply,

Thanks & Regards,

srinivasareddy.

0 Likes

Hello Srinivasareddy,

If you are using CY5677 BLE usb dongle with cysmart IDE, the device used in this dongle is Bluetooth version 4.2 and for the signed write operations you can refer Bluetooth spec 4.2 (Vol 3: Part F : 3.4.5.4 signed write command).

Could you please share the peripheral side logs also when you are performing this signed write operations.

Also, did you sniff the packets and confirmed that signature generated by both of the devices are not matching. Could you please elaborate bit more on how you are checking this?

Yes, the output generated by AES-CMAC is according to the BLE core spec 4.2.

Thanks,

P Yugandhar.

0 Likes