Simple KMU sample for the nRF9160 CC310

This sample demonstrates:

• Write a 128 bit AES key to a KMU slot.
  • This is typically done in production.
  • This code and the secret key must not remain in flash after the key has been written to the KMU (that would defeat the purpose of using the KMU).
• Use KMU key for crypto operations:
  • Push key to CryptoCell and
  • Use key to encrypt and decrypt a test vector using AES ECB.
  • This is typically done in the field and allows crypto operations without the CPU ever being able to access the key.

Notes:

• Only works in secure mode.
• Tested with NCS 1.4.0.