Freescale Semiconductor MPC8313E PowerQUICC II Pro Family Reference Manual page 683

Table 14-25 describes AESUMR fields.
Bits Name
The following bits are described for information only. They are not under direct user control.
0–50 — Reserved
51–53 SCM Sub-cipher-mode. Specifies additional options specific to particular cipher modes.
• XOR cipher mode: specifies the number of sources to be XORed together. Valid values are 2 and 3.
• For all other cipher modes, this field must be 0.
54–55 — Reserved, must be set to zero.
The following bits are controlled through the MODE0 field of the descriptor header.
56–57 ECM Extend cipher mode. Used in combination with bits 61–62 "Cipher Mode" to define the mode of AES
operation. See
58 FM Final MAC (FM). Processes final message block and generates final MAC tag at end of message processing
(CCM mode only)
0 Do not generate final MAC tag
1 Generate final MAC tag after CCM processing is complete.
59 IM Initialize MAC(IM). Initializes AESU for new message (CCM mode only)
0 Do not initialize (context will be loaded by host)
1 Initialize new message with nonce
60 RDK Restore decrypt key (RDK). Specifies that key data write will contain pre-expanded key (decrypt mode only).
See note below on use of RDK bit.
0 Expand the user key prior to decrypting the first block
1 Do not expand the key. The expanded decryption key will be written following the context switch.
61–62 CM Cipher mode. Used in combination with bits 56–57 (Extend Cipher Mode) to define the mode of AES
operation. See
63 ED Encrypt/Decrypt. If set, AESU operates the encryption algorithm; if not set, AESU operates the decryption
algorithm.
0 Perform decryption
1 Perform encryption
Note: This bit is ignored if CM is set to '11' (CTR mode).
MPC8313E PowerQUICC™ II Pro Integrated Processor Family Reference Manual, Rev. 2
Freescale Semiconductor
Table 14-25. AESUMR Field Descriptions
Table 14-26 for mode bit combinations.
Table 14-26 for mode bit combinations.
Table 14-26. AES Cipher Modes
Mode
ECB
CBC
CTR
1
SRT
CCM (without ICV comparison)
CCM with ICV comparison
Description
ECM (56–57) CM (61–62)
00 00
00 01
00 11
01 11
10 00
11 00
Security Engine (SEC) 2.2
14-41