Circuit Board Reference Manual

MCF548x Reference Manual, Rev. 3
22-72 Freescale Semiconductor
22.14.2 DEU Mode Options and Data Packet Descriptors
Figure 22-47 shows the DEU options that are programmable via the PMODE field in the descriptor header.
Table 22-56 describes DEU mode register fields.
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 MAC Out Length NULL
PTR_7 MAC Out Pointer NULL
PTR_NEXT Next Descriptor Pointer Pointer to next data packet descriptor
76543210
Field
— CETSED
Reset 0000_0000
Loc PMODE Field in DPD Header
Figure 22-47. DEU Mode Options
Table 22-56. DEU Mode Option Field Descriptions
Bits Name Description
0–4 — Reserved
5 CE CBC/ECB. If set, DEU operates in cipher-block-chaining mode. If not set, DEU operates in
electronic codebook mode.
0 ECB mode
1 CBC mode
6 TS Triple/Single DES. If set, DEU operates the Triple DES algorithm; if not set, DEU operates
the single DES algorithm.
0 Single DES (SDES)
1 Triple DES (TDES)
7 ED Encrypt/decrypt. If set, DEU operates the encryption algorithm; if not set, DEU operates
the decryption algorithm.
0 Perform decryption
1 Perform encryption
Table 22-55. Final Descriptor for a Statically Assigned AFEU (Continued)
Field Name Value/Type Description