Programming Model
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
26-135
Context should be loaded with the lower bytes in the lowest 64-bit Context Register. The Context
Registers are summarized in Figure 26-10.
Note:
See Section 26.4.3.9, AESU Context Registers, on page 26-44 for details on how to use
and program the Context Registers.
26.5.8.10 AESU Key Registers (AESUKR[1–3])
The AESU key registers hold from 16, 24, or 32 bytes of key data, with the first 8 bytes of key
data written to key 1. Any key data written to bytes beyond the value written to the Key Size
Register are ignored. The Key Data Registers are cleared when the AESU is reset or reinitialized.
If these registers are modified during message processing, a context error is generated.
The Key Data Registers may be read when changing context in decrypt mode. To resume
processing, the value read must be written back to the key registers and the restore decrypt key bit
must be set in the Mode Register. This eliminates the overhead of expanding the key prior to
starting decryption when switching context.
Note:
The AESU key registers are located at the following offsets:
AESUKR1 = Offset 0xC4400.
AESUKR2 = Offset 0xC4408
AESUKR3 = Offset 0xC4410
Context Register
(64 bits each)
Offset
Cipher Mode
ECB
CBC
CTR
SRT
CCM
1
0xC4100
—
IV1
1
—
Counter
1
IV
1
/MAC Tag
2
0xC4108
—
IV2
1
—
3
0xC4110
—
—
—
Counter Modulus
Exponent (M)
1
Encrypted MAC
2
/
Decrypted MAC/
Encrypted Counter
4
0xC4118
—
—
—
—
5
0xC4120
—
—
Counter
1
—
Counter
1
6
0xC4128
—
—
—
7
0xC4130
—
—
Counter Modulus
Exponent
1
—
Counter Modulus
Exponent
1
/
header size/
MAC size
3
Notes: 1.
Must be written at the start of a new message.
2.
Must be written at the start of a new CCM decryption.
3.
Header size/MAC size is only used if AES-CCM processing is suspended and resumed.
Figure 26-10. AESU Context Registers
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...