Freescale Semiconductor MCF5480 - Manual (Page 690)

MCF548x Reference Manual, Rev. 3
22-88 Freescale Semiconductor
22.14.5.3 AESU-CCM Mode Descriptor
The SEC supports single pass, single descriptor AES-CCM processing for generic
authenticate-and-encrypt block cipher. Table 22-85 shows a the descriptor format used for AES-CCM in
encryption mode. The descriptor loads a key and context (IV) into the AESU, performs the cipher on data,
and writes the result and context to memory.
In order to use this descriptor format the correct ordering for the context in and context out must be used.
Table 22-86 shows the format used for the context input for AES-CCM.
0x60000010 ECB Decrypt
0x60600010 CTR —
Table 22-85. Descriptor for a AES-CCM Encryption
Field Name Value/Type Description
Header 0x6B100010 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 in IV (always 56 bytes)
PTR_2 IV Pointer Address of IV
LEN_3 Key Length Number of bytes in Key (16 bytes)
PTR_3 Key Pointer Address of Key
LEN_4 Data In Length Number of bytes of data to be ciphered (39 bytes)
PTR_4 Data In Pointer Address of data to be ciphered
LEN_5 Data Out Length Bytes of output data (24 bytes)
PTR_5 Data Out Pointer Address to write output data
LEN_6 IV Out Length Number of bytes of output IV to be written (24 or 32 bytes)
PTR_6 IV Out Pointer Address where output IV 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 22-84. Typical Header Values for Using Final Static AESU Descriptor Format (Continued)
Header Value Mode E/D