SPMA083 January   2022 TM4C129CNCPDT , TM4C129CNCPDT , TM4C129CNCZAD , TM4C129CNCZAD , TM4C129DNCPDT , TM4C129DNCPDT , TM4C129DNCZAD , TM4C129DNCZAD , TM4C129EKCPDT , TM4C129EKCPDT , TM4C129ENCPDT , TM4C129ENCPDT , TM4C129ENCZAD , TM4C129ENCZAD , TM4C129LNCZAD , TM4C129LNCZAD , TM4C129XKCZAD , TM4C129XKCZAD , TM4C129XNCZAD , TM4C129XNCZAD

 

  1.   Trademarks
  2. 1Implementation
    1. 1.1 Flash Boot Loader Project
      1. 1.1.1 Changes to the Example Project boot_serial
        1. 1.1.1.1 Changes to bl_config.h
        2. 1.1.1.2 New Functions Added
          1. 1.1.1.2.1 MyCheckUpdateFunc
          2. 1.1.1.2.2 MyReinitFunc
          3. 1.1.1.2.3 MyEndFunc
          4. 1.1.1.2.4 MyDecryptionFunc
    2. 1.2 Image Creation Project
    3. 1.3 Key Image Project
    4. 1.4 EK-TM4C129EXL Example Application Project
    5. 1.5 DK-TM4C129X Example Application Project
    6. 1.6 RAM-Based EEPROM Erase Project
  3. 2Example Walk Through
    1. 2.1 Build Environment
    2. 2.2 Importing the Examples into Code Composer Studio
    3. 2.3 Setting Keys and Variables
      1. 2.3.1 Keys
      2. 2.3.2 Initialization Vector
      3. 2.3.3 Application Start Address and Flash Size
        1. 2.3.3.1 APP_BASE
        2. 2.3.3.2 APP_END
        3. 2.3.3.3 RAM_BASE
    4. 2.4 Running the shared_key_image_encrypt Tool
    5. 2.5 Running the Shared Key Serial Boot Loader
      1. 2.5.1 Programming the Boot Loader
        1. 2.5.1.1 Erasing Existing Code and Keys
          1. 2.5.1.1.1 Erasing Flash and EEPROM With Code Composer Studio
          2. 2.5.1.1.2 Erasing Flash and EEPROM by Using the Unlock Procedure
        2. 2.5.1.2 Using the ROM Boot Loader to Program the Shared Key Boot Loader
      2. 2.5.2 Using the Shared Key Boot Loader to Program the Application Code
    6. 2.6 Returning to the Boot Loader
  4. 3Summary

2.3.1 Keys

The keys are defined in the file key_image.asm that is in the key_image directory. This file is used in the key_image project and also, by link, in the shared_key_boot_serial example project.

 .sect ".keyimage"
 .global key
key
; Encryption/Decryption Key 0
     .word 0x3ed44417, 0x8d849ffc, 0x4719e4dc, 0x71583965
     .word 0x84b6ba7d, 0xa96ff68a, 0xb79d9da8, 0x5f747e02
; Authentication Key 0
     .word 0xf74e59bf, 0xd19cd4e1, 0x630303f8, 0xe5bb8089
     .word 0x0e3bc945, 0xffc85239, 0x53289e9c, 0x5f906df8
; Encryption/Decryption Key 1
     .word 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF
     .word 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF
; Authentication Key 1
     .word 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF
     .word 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF

As seen in the code, there are actually four 256-bit keys defined. The first key is for encryption/decryption. The second key is for authentication. The last two keys are currently not used.

For initial evaluation and development the keys given in this example can be used, but for a real project these need to be changed and kept confidential in a secure location.