Programming Model
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
26-125
IM
4
0
Initialize MAC
Used to initialize the AESU for a new message
(CCM mode only).
0
Do not initialize (context is loaded by core
processor).
1
Initialize new message with nonce.
RDK
3
0
Restore Decrypt Key
Specifies that key data writes contain pre-expanded
key (decrypt mode only).
Note:
In most networking applications, the
decryption of an AES protected packet is
performed as a single operation. However,
if circumstances dictate that the decryption
of a message should be split across
multiple descriptors, the AESU allows the
user to save the decrypt key, and the
active AES context, to memory for later
re-use. This saves the internal AESU
processing overhead associated with
regenerating the decryption key schedule
(~12 AESU clock cycles for the first block
of data to be decrypted.). For details, see
Section 26.4.3.1, AESU Mode Register,
on page 26-41
0
Expand the user key prior to decrypting the
first block.
1
Do not expand the key. The expanded
decryption key is written after the context
switch.
CM
2–1
0
Cipher Mode
Used in combination with the ECM field to define
the AES operating mode.
See Table 26-41 for details.
ED
0
0
Encryption/Decryption
Specifies whether to encrypt or decrypt the data.
0
Perform decryption.
1
Perform encryption.
Table 26-41. AES Cipher Modes
Mode
ECM
CM
ECB
00
00
CBC
00
01
CTR
00
11
SRT
01
11
CCM (without ICV comparison)
10
00
CCM with ICV comparison
11
00
XOR
11
11
Reserved
all others
Note:
SRT is not a new AES mode, it is an AESU method of performing AES-CTR mode with reduced context loading
overhead specifically for performing SRTP. It should be used with descriptor type 0010_0 srtp. See Section
26.4.3.9.3, Context for SRT Mode, on page 26-44 for more information on how SRT mode reduces context loading
overhead.
Table 26-40. AESUMR Field Descriptions (Continued)
Name
Reset
Description
Settings
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 ...