Texas Instruments CC3235 SimpleLink Series - AES_CTRL Register; AES_CTRL Register Field Descriptions

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SWRU543–January 2019
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Advance Encryption Standard Accelerator (AES)
17.4.21 AES_CTRL Register (Offset = 50h) [reset = X]
AES_CTRL is shown in Figure 17-34 and described in Table 17-24.
Return to Summary Table.
Determines the mode of operation of the AES engine.
Figure 17-34. AES_CTRL Register
31 30 29 28 27 26 25 24
CONTEXT_RE
ADY
SAVE_CONTE
XT_READY
SAVE_CONTE
XT
RESERVED CCM_M
RO-1h RO-0h R/W-0h R-X R/W-0h
23 22 21 20 19 18 17 16
CCM_M CCM_L CCM GCM
R/W-0h R/W-0h R/W-0h R/W-0h
15 14 13 12 11 10 9 8
CBCMAC F9 F8 XTS CFB ICM CTR_WIDTH
R/W-0h R/W-0h R/W-0h R/W-0h R/W-0h R/W-0h R/W-0h
7 6 5 4 3 2 1 0
CTR_WIDTH CTR MODE KEY_SIZE DIRECTION INPUT_READY OUTPUT_REA
DY
R/W-0h R/W-0h R/W-0h R/W-0h R/W-0h RO-0h RO-0h
LEGEND: R/W = Read/Write; R = Read only; W1toCl = Write 1 to clear bit; -n = value after reset
Table 17-24. AES_CTRL Register Field Descriptions
Bit Field Type Reset Description
31 CONTEXT_READY RO 1h
If 1, this read-only status bit indicates that the context data registers
can be overwritten, and the host is permitted to write the next
context.
30 SAVE_CONTEXT_READY RO 0h
If 1, this read-only status bit indicates that an AES authentication
TAG or IV blocks are available for the host to retrieve. This bit is only
asserted if the ‘save_context’ bit is set to 1. The bit is mutually
exclusive with the ‘context_ready’ bit.
29 SAVE_CONTEXT R/W 0h
This bit indicates that an authentication TAG or result IV must be
stored as a result context. If this bit is set, context output DMA or
interrupt are asserted if the operation is finished and related signals
are enabled.
28-25 RESERVED R X
24-22 CCM_M R/W 0h
Defines “M” that indicated the length of the authentication field for
CCM operations; the authentication field length equals two times (the
value of CCM-M plus one). The AES engine always returns a 128-bit
authentication field, of which the M least significant bytes are valid.
All values are supported.
21-19 CCM_L R/W 0h
Defines “L” that indicated the width of the length field for CCM
operations; the length field in bytes equals the value of CMM-L plus
one. Supported values for L are (programmed value): 2 (1), 4 (3) and
8 (7).
18 CCM R/W 0h
AES-CCM is selected; this is a combined mode, using AES for both
authentication and encryption. No additional mode selection is
required.
0h = Other mode selected
1h = CCM mode selected