Per-message authentication for ESP-IDF v6.0.x with a pre-shared installation key. Wraps a message in a 28-byte envelope (sender, receiver, epoch, counter, 128-bit HMAC-SHA256 tag) and rejects forged, altered, misaddressed and replayed messages. Pure logic on bytes: works over UDP, UART, BLE or anything else. PSA Crypto only, no encryption, no tasks, no allocations after create.
Boards of ESP-IDF programs described once as data: pins, buses and parts, each fact with where it comes from. The board is chosen once; the component sets its hardware up through the library of each part, and the program asks for what it needs by kind, never by the board's name. A build downloads only the libraries the chosen board needs.