AN2492 Freescale Semiconductor / Motorola, AN2492 Datasheet - Page 24

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

Additional Examples
Additional Examples
Note that the descriptor header value is the same as the value used in the static assignment example. The
descriptor header does not determine static vs. dynamic assignment (this is a difference from the MPC190).
In the MPC184, static assignment is entirely controlled by the EU assignment control register in the
controller (see Chapter 8 in the MPC184 Security Co-Processor User’s Manual, PCI Interface, for more
information on the EUACR.) When an EU is statically assigned to a channel, it will use keys and context
from the current descriptor for the following descriptor, until the EU is reset and released from static
assignment. Releasing an EU, then resetting it, is not recommended, as any channel with an outstanding
request for an EU of the type being released could be dynamically assigned the EU before the previous key
and context was cleared by the reset. When a channel has been dynamically assigned an EU, the channel
will automatically reset the EU before releasing it for use by another channel.
9 Additional Examples
In the following sections are descriptor examples of some common cryptographic transforms. Also provided
are tables of derivative descriptor headers for closely related transforms.
9.1 Dynamically Assigned 3DES-HMAC-SHA-1 Decrypt
Table 19 shows a dynamic descriptor example of an inbound IPSec ESP transform.
24
Header
LEN_1
PTR_1
LEN_2
PTR_2
LEN_3
PTR_3
LEN_4
PTR_4
LEN_5
PTR_5
LEN_6
PTR_6
LEN_7
(Inbound IPSec ESP)
Field
MPC184 Descriptor Programmer’s Guide— PCI View
Freescale Semiconductor, Inc.
0x2063_1C22
Table 19. Representative Descriptor DPD_Type
Value/Type
For More Information On This Product,
0010_3DES_CBC_HMAC_SHA-1_Decrypt
Pointer
Pointer
Pointer
Pointer
Pointer
Pointer
Length
Length
Length
Length
Length
Length
Length
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DPD_Type 0010_3DES_CBC_HMAC_SHA-1_Decrypt
Number of bytes of HMAC key to be written to MDEU key register
PCI address of HMAC key
Number of bytes to be HMAC’d
PCI address of data to be HMAC’d
Number of bytes of key to be written to DEU key register (must be
16 or 24)
PCI address of key
Number of bytes of IV to be written to DEU IV register (always 8)
PCI address of IV
Number of bytes of ciphertext to be decrypted
PCI address of ciphertext to be decrypted
Number of bytes of plaintext to be written out to memory (should be
equal to length of data-in)
PCI address where plaintext is to be written
Number of bytes of HMAC to be written to PCI memory space
(always 20 for HMAC-SHA-1)
Description
MOTOROLA