Freescale Semiconductor MCF5480 - Manual (Page 671)

EU Specific Data Packet Descriptors
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 22-69
Table 22-51 shows the descriptor format to load a previously generated context into the AFEU. Then the
input data is ciphered and the context is unloaded.
22.14.1.2 Statically Assigned AFEU
Statically assigning the AFEU to a particular crypto-channel permits the AFEU to retain state between data
packets. The following descriptors support state-retention. Table 22-52 shows the descriptor format to load
a key into the AFEU and perform the initial context-permutation.
LEN_7 MD Out Length NULL
PTR_7 MD Out Pointer NULL
PTR_NEXT Next Descriptor Pointer Pointer to next data packet descriptor
Table 22-51. Descriptor for a Dynamically Assigned AFEU Using Context
Field Name Value/Type Description
Header 0x1070_0050 Don’t permute, context from FIFO, and dump context
(TYPE 0101)
LEN_1 Length (not used) NULL
PTR_1 Pointer (not used) NULL
LEN_2 IV Length Number of bytes in context (259 bytes)
PTR_2 IV Pointer Address of context to be loaded into AFEU
LEN_3 Key Length NULL
PTR_3 Key Pointer NULL
LEN_4 Data In Length Number of bytes of data to be ciphered.
PTR_4 Data In Pointer Pointer to data to perform cipher upon
LEN_5 Data Out Length Number of bytes of data after ciphering
PTR_5 Data Out Pointer Pointer to location where cipher output is to be written
LEN_6 IV Out Length Number of bytes in context (259 bytes)
PTR_6 IV Out Pointer Address where AFEU context output is to be written
LEN_7 MD Out Length NULL
PTR_7 MD Out Pointer NULL
PTR_NEXT Next Descriptor Pointer Pointer to next data packet descriptor
Table 22-52. First Descriptor for a Statically Assigned AFEU Using a Key
Field Name Value/Type Description
Header 0x1000_0050 Perform permute (TYPE 0101)
LEN_1 Length (not used) NULL
Table 22-50. Descriptor for a Dynamically Assigned AFEU Using a Key (Continued)
Field Name Value/Type Description