nrf_ecb_crypt

RE: nrf_ecb_crypt

endnode — Fri, 01 May 2015 07:10:56 GMT

Well if you port some open source C implementation of AES decrypt function then you willl cry because performance will be hardly usable. Better choice is probably designing protocols where you need only AES encryption.

RE: nrf_ecb_crypt

Milan — Fri, 01 May 2015 06:01:21 GMT

clear!! AES block is only for encryption!! Thanks!!

RE: nrf_ecb_crypt

Milan — Fri, 01 May 2015 04:24:42 GMT

I read all posts of earlier topic but I am not getting clear view. Is it possible to decrypt AES ECB data using Nordic API's? or Do I need to port some other library on Nordic?

Please give your valuable comments.

Thanks!!

RE: nrf_ecb_crypt

endnode — Thu, 30 Apr 2015 21:20:55 GMT

Hi Milan, have you read all responses to your previous question on the same topic?

Nordic nRF51 ICs and Soft Device API do not support AES decryption, only encryption. So the result of nrf_ecb_crypt function call are always AES-128 ECB encrypted data. So your test vector is:

AES-128-ECB-ENCRYPT(clear text = 0x3DB77B406B1D5B38A3CF34FB27D83B8E, key = 0x5A34F5F2BB0C6FEF8E9480DEE1316C51) = 0x7ED754853E36C3E3FFCFF4484F56F10D

rather then

AES-128-ECB-DECRYPT(clear text = 0x3DB77B406B1D5B38A3CF34FB27D83B8E, key = 0x5A34F5F2BB0C6FEF8E9480DEE1316C51) = 0x35613334663566326262306336666566 (aka "5a34f5f2bb0c6fef" in ASCII;).

What is definitely confusing is description of AES ECB encryption module in Nordic's documentation but even they say "encryption/decryption" there is no input flag which would determine which operation will be performed and it (obviously) cannot be visible just from the inputs (key or cypher text data).

Cheers Jan