RE: CryptoCell CC310 AES CCM* MAC length other than zero

chris-ho — Thu, 01 Mar 2018 07:46:15 GMT

Jakub Rzeszutko thank you very much, that's what i missed.

the nonce array posted was taken from my test set whereas the CRYS_AESCCMStar_NonceGenerate overwrites that and there i didn't updated the tag_len...

RE: CryptoCell CC310 AES CCM* MAC length other than zero

Jakub Rzeszutko — Thu, 01 Mar 2018 07:31:46 GMT

Hi,

First of all when you are changing size of tag you need to update nonce array well:

tag_len == 0   last value in nonce array == 4
tag_len == 4   last value in nonce array == 5
tag_len == 8   last value in nonce array == 6
tag_len == 16 last value in nonce array == 7

If you will not do it you will receive an error: CRYS_AESCCM_ILLEGAL_PARAMETER_ERROR.

So for tag_len == 0 you shall have following nonce array:

CRYS_AESCCMStar_Nonce_t nonce_n =
{ 0x00, 0x00, 0xf0, 0xe0, 0xd0, 0xc0, 0xb0, 0xa0, 0x00, 0x00, 0x00, 0x00, 0x04 };