CC2510FX Datasheet, PDF (137/253 Pages) List of Unclassifed Manufacturers – True System-on-Chip with Low Power RF Transceiver and 8051 MCU

CC2510Fx / CC2511Fx
The Additional Authentication Data is
appended to the A_Data length field L(a).
The Additional Authentication Blocks is
padded with zeros until the last Additional
Authentication Block is full. There is no
restriction on the length of a.
AUTH-DATA = L(a) + Authentication Data
+ (zero padding)
(4) The last block of the message is
padded with 0s until full (that is if its length
is not a multiple of 128).
(5) The software concatenates the block
B0, the Additional Authentication Blocks if
any, and the message;
Input message = B0 + AUTH-DATA +
Message + (zero padding of message)
(6) Once the input message authentication
by CBC-MAC is finished, the software
leaves the uploaded buffer contents
unchanged (M=16), or keeps only the
buffer’s higher M bytes unchanged, while
setting the lower bits to 0 (M != 16).
The result is called T.
Message Encryption
(7) The software creates the key stream
block A0. Note that L=6, with the current
example of the CTR generation. The
content is shown in Figure 29:
Name
Designation
A0
First CTR value for CCM mode
Byte 0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Name Flag
NONCE
CTR
Figure 29: Message Encryption Phase Block 0
Note that any value but zero works for the
CTR value.
The content of the Encryption Flag byte is
described in Figure 30
Bit
Name
Value
Name
FLAG/A0
7
6
Reserved
0
0
Designation
Encryption Flag Field for CCM mode
5
4
3
2
-
0
0
0
1
1
L-1
0
0
1
Figure 30: Encryption Flag Byte
(8) The software loads A0 by selecting a
Load IV/Nonce command. To do so, it sets
Mode to CFB or OFB at the same time it
selects the Load IV/Nonce command.
(9) The software calls a CFB or an OFB
encryption on the authenticated data T.
The uploaded buffer contents stay
unchanged (M=16), or only its first M bytes
stay unchanged, the others being set to 0
(M-16). The result is U, which will be used
later.
(10) The software calls a CTR mode
encryption right now on the still padded
message blocks. It does not have to
reload the IV/CTR.
(11) The encrypted authentication data U
is appended to the encrypted message.
This gives the final result, c.
Result c = encrypted message(m) + U
Message Decryption
CC2510Fx/CC2511Fx PRELIMINARY Data Sheet (Rev. 1.2) SWRS055A Page 137 of
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