Freescale Semiconductor MCF5480 - Manual (Page 681)

EU Specific Data Packet Descriptors
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 22-79
(outbound) or compare the hash generated by the SEC with the hash which was received with the packet
(inbound). If the hashes match, the packet integrity check passes.
Table 22-68 lists several different descriptors that use the format shown in Table 22-67 .
22.14.3.3 Statically Assigned MDEU
Table 22-69 shows the first descriptor for a statically assigned MDEU.
Table 22-67. Descriptor for a Dynamically Assigned MDEU
Field Name Value/Type Description
Header see Table 22-68 Header common to several descriptors (TYPE 0001)
LEN_1 Length (not used) NULL
PTR_1 Pointer (not used) NULL
LEN_2 IV Length Number of bytes of IV to be written (optional) (40 bytes)
PTR_2 IV Pointer Pointer to context to be written into MDEU (optional)
LEN_3 Key Length Number of bytes of key (only used for HMAC mode)
PTR_3 Key Pointer Pointer to key (only used for HMAC mode)
LEN_4 Data In Length Number of bytes of data to be hashed
PTR_4 Data In Pointer Pointer to data to perform hash upon
LEN_5 Data Out Length NULL
PTR_5 Data Out Pointer NULL
LEN_6 IV Out Length Number of bytes of data after hashing (16, 20, or 32 for
hash result. 40 bytes for full context including message
length count.)
PTR_6 IV Out Pointer Pointer to location where hash output is to be written
LEN_7 MAC Out Length NULL
PTR_7 MAC Out Pointer NULL
PTR_NEXT Next Descriptor Pointer Pointer to next data packet descriptor
Table 22-68. Typical Header Values for Dynamic MDEU Format
Header Value Algorithm HMAC Pad
0x30500010 SHA256 No Yes
0x30600010 MD5 No Yes
0x30400010 SHA No Yes
0x31D0010 SHA256 Yes Yes
0x31E00010 MD5 Yes Yes
0x31C00010 SHA Yes Yes