CC2430 Datasheet, PDF (139/212 Pages) Texas Instruments – A True System-on-Chip solution for 2.4 GHz IEEE 802.15.4 / ZigBee-TM

CC2430
Peripherals : AES Coprocessor
(7) The software calls a CTR mode decryption
right now on the encrypted message blocks C.
It does not have to reload the IV/CTR.
Reference Authentication tag generation
This phase is identical to the Authentication
Phase of CCM encryption. The only difference
is that the result is named MACTag (instead of
T).
Message Authentication checking Phase
The software compares T with MACTag.
13.12.6 Sharing the AES coprocessor between layers
The AES coprocessor is a common resource
shared by all layers. The AES coprocessor can
only be used by one instance one at a time. It
is therefore necessary to implement some kind
of software semaphore to allocate and de-
allocate the resource.
13.12.7 AES Interrupts
The AES interrupt, ENC, is produced when
encryption or decryption of a block is
completed. The interrupt enable bit is
IEN0.ENCIE and the interrupt flag is
S0CON.ENCIF.
13.12.8 AES DMA Triggers
There are two DMA triggers associated with
the AES coprocessor. These are ENC_DW
which is active when input data needs to be
downloaded to the ENCDI register, and
ENC_UP which is active when output data
needs to be uploaded from the ENCDO register.
The ENCDI and ENCDO registers should be set
as destination and source locations for DMA
channels used to transfer data to or from the
AES coprocessor.
13.12.9 AES Registers
The AES coprocessor registers have the
layout shown in this section.
CC2430 Data Sheet (rev. 2.1) SWRS036F
Page 139 of 211