In the different customer stages from development to volume production, the J7 series SoC provides several device types according to the different requirements of security, as shown in Figure 1-1.

• GP device: General-Purpose device type, can be production device, but normally used in development considering security.
• HS-SE-TIDK device: High Security device contains TI keys, and TI dummy keys in the customer area. TIDK devices can never be production devices.
• HS-FS device: High Security-Field Securable device, the customer area is blank. The HS-FS device needs to program keys before delivery to the end-customer.
• HS-SE device: High Security-Security Enforced device. The customer has programmed their keys into the customer area. The HS-SE devices can be production devices.

Different device types bring different security features, but also different restrictions. The GP device has no safety features, so the JTAG port is unlocked and all the binaries do not need to be signed and encrypted, so it is usually used as a development device. The HS device enforces the security feature, but the JTAG port is locked and all the binaries must be signed and encrypted, so it is usually used as a production device. The customer can see the development flow in Figure 1-2 to complete the HS process.

The recommended process is:

• Customer engineers do their development on GP device; meanwhile the HS engineers start their security development on HS-SE-TIDK device, to ensure the correctness of the HS sign and encrypt operation.
• The HS engineers purchase HS-FS device and use TI dummy keys or random dummy keys to double check the HS process. In order to confirm the process of keys generation, Keywriter setup, and eFuse programming.
• Synthesize the work of GP and the security branch of HS-FS, also the customer needs to setup their HSM and program customer keys into eFuse, and use the same customer keys to sign and encrypt the system image.

Lot of keys are used during the security process in the J7 device, as shown in Table 1-1. The notes describe important keys during HS development. The SMPKH, SMEK, BMPKH, and BMEK are programmed into eFuse to authenticate and decrypt the system image. The AES-256 key and TI FEK public key are used to protect the key programming process.

TI also provides test keys in the Keywriter package. Customers can use these test keys to go through the complete HS process, then setup up their HSM and use customer keys to complete these tasks before production.