AN2492 Freescale Semiconductor / Motorola, AN2492 Datasheet - Page 11

• Manufacturer Part Number: AN2492
• Description: MPC184 Descriptor Programmers Guide--PCI View
• Manufacturer: Freescale Semiconductor / Motorola

4.4.1 Recommended Settings for MDEU Mode Register
The most common task likely to be executed via the MDEU is HMAC generation. HMACs are used to
provide message integrity within a number of security protocols, including IPSec and SSL/TLS. When the
HMAC is being generated by a single dynamic descriptor (the MDEU acting as sole or secondary EU), the
following mode register bit settings should be used:
When the HMAC is being generated for a message that is spread across a chain of static descriptors, the
following mode register bit settings should be used:
Additional information on descriptors can be found in Chapter 6 of the MPC184 Security Co-Processor
User’s Manual, PCI Interface.
MOTOROLA
Bits
1:0
2
•
•
•
Continue—Off
Initialize—On
HMAC—On
Autopad—On
First Descriptor:
Continue—On
Initialize—On
HMAC—On
Autopad—Off
Middle Descriptor(s):
Continue—On
Initialize—Off
HMAC—Off
Autopad—Off
Final Descriptor
Continue—Off
Initialize—Off
HMAC—On
Autopad—On
Signal
ALG
PD
MPC184 Descriptor Programmer’s Guide— PCI View
If set, configures the MDEU to automatically pad partial message blocks.
0 Do not autopad
1 Perform automatic message padding whenever an incomplete message block is
Message digest algorithm selection
00 SHA-160 algorithm (full name for SHA-1)
01 SHA-256 algorithm
10 MD5 algorithm
11 Reserved
detected
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For More Information On This Product,
Table 6. MDEU Mode Register (continued)
Go to: www.freescale.com
Description
Execution Unit Mode Data
11