5812-DS00-R datasheet(31/84 Pages) BOARDCOM

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Advance Data Sheet

BCM5812

3/11/03

B roa dcom Co rpo rat ion

Document

5812-DS01-405-R

Cryptographic Operations

Page 23

Figure 22: Pure MD5/SHA-1 Hash Command Context

The input structures are the same as for ARCFOUR, Figure 20 on page 21. The packet length must equal the total of the

input fragment lengths.

The hash output is written to the address in the next output fragment chained entry in the packet descriptor. The size of the

hash written is determined by the algorithm, 16 bytes for MD5 and 20 bytes for SHA-1. The output fragment length for this

descriptor must be zero.

IPSEC AES

The BCM5812 provides FIPS-197 [15] compliant AES. It supports the 128 bit blocksize, with key sizes of 128, 192, and 256

bits.

Figure 23 shows the AES command context. AES processing is very similarly to 3DES, with the following differences:

•

the block size is always 128 bits, as is the IV

•

the key can be 128, 192, or 256 bits

•

counter mode (CTR) is supported in addition to CBC.

The AES command context flags are detailed in Table 9 on page 24. The command context size depends on the AES key

size, as shown in Table 8. This command uses MCR1@. The opcode for this command is 0x40.

Table 7: Pure MD5/SHA-1 Hash Command Context Flags

Bits

Definition

15:14

Reserved

13:12

Authentication:

• 00 = Invalid

• 01 = MD5

• 10 = SHA-1

• 11 = Invalid

11:0

Reserved

LE N G T H

Pure M D 5/SH A-1 H ash C ontext

O P CO DE

RE S E RV E D

R ESE R VED

FLAG S

15 14 13 12

Reserved

flag s

LE N G T H

Pure M D 5/SH A-1 H ash C ontext

O P CO DE

RE S E RV E D

R ESE R VED

FLAG S

15 14 13 12

Reserved

flag s

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