SNMPv3 Integration on STM32H723

I already have basic SNMP v1 “get” and “trap” working on an STM32H723-based board, but now the device must speak full SNMP v3 with security enabled. On the application layer I need you to add:

• Authentication: SHA (usmHMACSHAAuthProtocol)
• Privacy/Encryption: AES-128 (usmAesCfb128PrivProtocol)
• Message handling: both Trap and Get operations exactly as they work today in v1, only now wrapped in v3 security headers

The middleware, BSP, FreeRTOS tasks and UDP stack are in place; your task is to extend the existing agent code (currently using lwIP’s raw API) so that the MCU can:

1. Build and send authenticated, encrypted traps to our NMS.
2. Respond to encrypted, authenticated Get (and ideally GetNext) requests.
3. Expose a simple hook where I can register additional OIDs.

Acceptance criteria
• Wireshark capture shows v3 packets with authPriv, SHA + AES-128, and a valid engine ID.
• Net-SNMP snmpget/snmptrapd can communicate successfully using the provided user/keys.
• Code builds in STM32CubeIDE and fits within current Flash/RAM limits.

Timing is critical, so I am looking for someone who has already implemented SNMP v3 on embedded targets (preferably STM32 + lwIP) and can dive straight into the codebase. We will work through a shared Git repository; please be ready to start immediately.