Glossary and Abbreviations

This page defines abbreviations and recurring terms used across the wiki, README, changelog, and API docs.

Protocol and packet terms

ABI: Application Binary Interface. The stable C-callable surface exposed by C-Headers/sedsnet.h.
AAD: Additional Authenticated Data. Header bytes that are not encrypted but are authenticated by the E2E payload wrapper so tampering is detected before handlers see the payload.
AEAD: Authenticated Cryptography with Associated Data. The style of cryptography expected from cryptography providers: encrypt the payload and authenticate both payload and selected visible header bytes.
CRC: Cyclic Redundancy Check. Packed frames include a CRC32 trailer to reject corrupted bytes before dispatch.
E2E: End-to-end. In this project it can mean either end-to-end reliable delivery confirmation or end-to-end encrypted payloads, depending on context.
Frame: A packed packet byte sequence ready to send over a side.
Packet: The logical telemetry message before packing or after unpacking. It has a sender, time, data type, endpoints, and payload.
Payload: The application data bytes inside a packet. With cryptography, these bytes can be wrapped by the E2E encrypted payload format.
ULEB: Unsigned Little Endian Base 128. A compact variable-length integer encoding used in parts of the wire format.

CAN: Controller Area Network. A fixed-frame bus that usually benefits from packed-side max-size splitting.
Endpoint: A logical destination such as RADIO, SD_CARD, or FLIGHT_SOFTWARE.
Flooding: Forwarding to every eligible side. Current discovery-aware routing avoids blind unknown-route flooding for normal user data once topology exists.
I2C: Inter-Integrated Circuit. A short-distance bus that can benefit from fixed-size packed-side splitting.
Link-local: Traffic that should stay on local software-bus or IPC sides and not be advertised onto normal network links.
LoRa: Long Range radio. Usually low bandwidth and sometimes time-sliced, so discovery-aware routing, link probes, queueing, and TX-busy retry behavior matter.
RX: Receive.
Side: A router or relay connection to a transport, such as UART, CAN, RADIO, TCP, or a software bus.
TX: Transmit.
UART: Universal Asynchronous Receiver/Transmitter. A common serial transport.

Discovery: The internal control plane that advertises reachable endpoints, time sources, schema, and topology so routers and relays can route selectively.
Network variable: A data type whose latest packet is cached by routers/relays with local read/write permissions. Getters read the local cache and request refresh when missing or stale; setters publish a new value for the network.
Managed variable: Legacy wording for a network variable or latest-value cache. Current user docs prefer network variable.
Schema: Runtime definitions for endpoints and data types. In v4, user schema is registered, seeded from JSON, or learned through discovery instead of generated at compile time.
Topology: The discovered graph of boards, sides, reachable endpoints, time sources, and connections. Exported topology uses advertised endpoint and side names where available.

Credential: A compact signed authorization record issued by a master/root key. The built-in managed credential helper stores subject, key id, epoch, validity window, and permission bits.
HMAC: Hash-based Message Authentication Code. Used by the software fallback and managed credential helper for authentication.
Key ID: An application-defined number used by routers and cryptography providers to select the symmetric key or provider context for a packet.
MITM: Man in the middle. An active attacker that can intercept and modify key exchange or traffic. E2E cryptography resists MITM only when the key source is authenticated, for example by a provisioned root key, PSK, or master-issued credential.
PSK: Pre-shared key. A key provisioned before deployment and used to authenticate peers, derive traffic keys, or verify a master/root authority.
Root/master node: The authority that issues credentials or approves network state in deployments that avoid user-managed certificate files.

CMake wrapper target: Optional CMake targets such as sedsnet::c_wrapper and sedsnet::cpp_wrapper that provide convenience APIs on top of the raw C ABI.
Criterion: The Rust benchmarking framework used by the benchmark smoke pass.
Doctest: A Rust documentation code example compiled and run as a test by cargo test --doc.
nextest: An optional faster Rust test runner. ./build.py test auto-detects cargo-nextest and falls back to Cargo's built-in runner when it is not installed.
Smoke test: A validation run intended to catch obvious breakage, not a strict performance gate. The benchmark smoke pass executes Criterion benchmarks using the sedsnet_smoke baseline.