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Cryptographic Acceleration Unit (CAU)
24-3
Freescale Semiconductor
•
SHA-1
This selection of algorithms provides excellent support for network security standards (SSL, IPsec).
Additionally, using the CAU efficiently permits the implementation of any higher level functions or modes
of operation (HMAC, CBC, etc.) based on the supported algorithm.
The CAU is an instruction-level ColdFire coprocessor. The cryptographic algorithms are implemented
partially in software with only functions critical to increasing performance implemented in hardware. The
ColdFire coprocessor allows for efficient, fine-grained partitioning of functions between hardware and
software.
•
Implement the innermost round functions by using the coprocessor instructions
•
Implement higher-level functions in software by using the standard ColdFire instructions
This partitioning of functions is key to minimizing size of the CAU while maintaining a high level of
throughput. Using software for some functions also simplifies the CAU design. The CAU implements a
set of 22 coprocessor commands that operate on a register file of eight 32-bit registers. It is tightly coupled
to the ColdFire core and there is no local memory or external interface.
24.1.3
Features
The CAU includes these distinctive features:
•
Supports DES, 3DES, AES, MD5, SHA-1 algorithms
•
Simple, flexible programming model
24.2
Memory Map/Register Definition
The CAU only supports longword operations and register accesses. All registers support read, write, and
ALU operations. However, only bits 1–0 of the CASR are writeable. Bits 31–2 of the CASR must be
written as 0 for compatibility with future versions of the CAU.
Table 24-1. CAU Memory Map
Code
Register
DES
AES
SH
A-
1
MD5
Access
Reset Value
Section/Page
0
CAU status register (CASR)
—
—
—
—
R/W
0x1000_0000
1
CAU accumulator (CAA)
—
—
T
a
R
0x0000_0000
2
General purpose register 0 (CA0)
C
W0
A
—
R
0x0000_0000
3
General purpose register 1 (CA1)
D
W1
B
b
R
0x0000_0000
4
General purpose register 2 (CA2)
L
W2
C
c
R
0x0000_0000
5
General purpose register 3 (CA3)
R
W3
D
d
R
0x0000_0000
6
General purpose register 4 (CA4)
—
—
E
—
R
0x0000_0000
7
General purpose register 5 (CA5)
—
—
W
—
R
0x0000_0000
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...