Datasheet

Figure 14-4. DES3DES-CFB Feedback Mode
Input buffer
(plain text)
DES core
(encrypt)
Output buffer
(cipher text)
Key register
128
64
192
data_in
data_out
Key in
Encryption
Temporary
register
64
64
64
IV register
64
Input buffer
(cipher text)
DES core
(encrypt)
Output buffer
(plain text)
Key register
64
64
192
data_in
data_out
Key in
Decryption
Temporary
register
64
64
64
IV register
64
14.5 DES Module Programming Guide -Low Level Programming Models
14.5.1 Surrounding Modules Global Initialization
14.5.1.1 Main Sequence - DES Global Initialization
This procedure initializes the DES after a POR.
Table 14-3. DES Global Initialization
ValueRegister/Bit Field/Programming ModelStep
0x1DES_SYSCONFIG[1] SOFTRESETExecute software reset.
= 0x1DES_SYSSTATUS[0] RESETDONEWait for reset to complete
0x0DES_SYSCONFIG[3:2] SIDLESelect force idle mode
See the programming modelsSelect the algorithm type (DES or 3DES)
-DES_CTRL[5:4] MODESelect the operating mode (ECB, CBC or CFB).
≠ 0x0DES_CTRL[5:4] MODEIF: ECB operating mode not selected.
-DES_IV_L[31:0] IV_LLoad the initialization vector LSW.
-DES_IV_H[31:0] IV_HLoad the initialization vector MSW.
-DES_LENGTH[31:0] LENGTHDefine the cryptographic data length.
ENDIF
-DES_CTRL[2] DIRECTIONSelect encryption or decryption.
14.5.1.2 Subsequence - Configure the DES Algorithm Type
This subsequence details the DES algorithm type settings.
1043December 13, 2013
Texas Instruments-Advance Information
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TM4C129XNCZAD Microcontroller