Freescale Semiconductor MCF5329 Reference Manual page 775

Field
5 Initialization. Performs algorithm specific initialization of the digest registers. Most operations require this bit to be
INIT set. Only static operations that are continuing from a known intermediate hash value should clear this bit.
0 Do not perform initialization
1 Initialize the selected algorithm's starting registers
4–3 Message authentication code. Performs message authentication on messages. Requires keys loaded into the
MAC context and key registers.
00 Do not perform MAC
01 Perform HMAC
10 Perform EHMAC
11 Reserved
2 Pad data bit. Performs automatic message padding on the current partial message block.
PDATA 0 Do not perform padding
1 Perform padding
1 Reserved, should be cleared.
0 Algorithm. Selects which algorithm the MDHA module uses
ALG 0 Secure Hash Algorithm (SHA-1)
1 Message Digest 5 (MD5)
33.2.1.1 Invalid Modes
The following mode combinations trigger an interrupt to the interrupt controller and set the mode error bit
in the MDHA interrupt status register.
MDMR bit settings
Setting any reserved bits.
IPAD=1
IPAD=1
OPAD=1
MAC=10
(EHMAC)
MAC=10
(EHMAC)
MAC=10
(EHMAC)
MAC=01
(HMAC)
MAC=01
(HMAC)
Freescale Semiconductor
Table 33-2. MDMR Field Descriptions (continued)
Description
Table 33-3. Invalid MDMR Bit Settings
OPAD=1 Asserting both of the signals at the same time causes a mode to
occur that the MDHA is not capable of performing. These two
modes must be performed separately.
PDATA=1 According to HMAC and EHMAC standards no padding is done
to the data when the IPAD function is performed.
PDATA=1 According to HMAC and EHMAC standards no padding is done
to the data when the OPAD function is performed.
IPAD=1 MDHA requires that the IPAD step be performed as a separate
hash operation than message authentication.
OPAD=1 MDHA requires that the OPAD step be performed as a separate
hash operation than message authentication.
ALG=1 The standard for EHMAC is only defined for the SHA-1 algorithm.
(MD5)
IPAD MDHA requires that the IPAD step be performed as a separate
hash operation than message authentication.
OPAD MDHA requires that the OPAD step be performed as a separate
hash operation than message authentication.
MCF5329 Reference Manual, Rev 3
Message Digest Hardware Accelerator (MDHA)
Comments
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33-5