User Manual

Apollo3 Blue Datasheet

DS-A3-0p9p1 Page 174 of 909 2019 Ambiq Micro, Inc.

4.3 Secure OTA

Apollo3 Blue MCU supports secure OTA leveraging the Ambiq secure boot loader. Customers can update

any firmware component securely as directed via the security policy configuration in OTP.

The basic flow is shown in Figure 10.

Figure 10. Secure OTA Flow

4.4 Secure Key Storage

Key Storage is managed in hardware and provides secure access to keys as needed to support secure

boot as well as any other runtime security operation. A customer key bank is provided and can be

provisioned and allocated as required to support various configurations.

It may also be necessary to initiate key revocation in the event a particular key is compromised, stale or

needing to be refreshed. The Apollo3 Blue MCU provides key revocation for customer key bank keys as

needed. The number of key revocations supported is dependent on the length of keys required and the

partitioning/allocation of the key bank.

4.5 External Flash Inline Encrypt/Decrypt

External flash is supported on Apollo3 Blue MCU via the MSPI controller interface. The MSPI controller

supports inline encrypt/decrypt to enable customers to securely store firmware or any other secure image

data in external flash without concern of the firmware/data confidentiality being compromised.

Initiate OTA

Additional OTA Updates?

yes

Download Secure

Blob(s)

ERROR

Error

Downloads with Secure

OTA Installer

Secure OTA

Verification/

Decryption/Installation

Initiate Secure Boot

with New Image