Sdjs-217 -

| Layer | Primitive | Reason | |-------|-----------|--------| | Key derivation | HKDF‑SHA‑256 with node‑specific salt | Guarantees forward secrecy across schema updates. | | Encryption | AES‑GCM‑256 (or ChaCha20‑Poly1305 on 32‑bit CPUs) | Authenticated encryption with minimal overhead. | | Signature | Ed25519 (or ECDSA‑P‑256) | Small public keys (~32 B) and fast verification on MCUs. | | Hashing | BLAKE2b‑256 for schema integrity | Faster than SHA‑2 on most embedded cores. |

1. Overview SDJS‑217 (Secure Distributed JSON Schema, version 217) is a lightweight, extensible schema‑definition and validation framework designed specifically for the constrained environments of the Internet of Things (IoT). It combines three core capabilities: sdjs-217

For organisations seeking a data contract layer that can evolve without service interruption, SDJS‑217 provides a pragmatic yet forward‑looking foundation—one that is already being referenced in emerging IoT‑security standards bodies (IETF WG‑IoTSec, ISO/IEC 30141). Prepared by the OpenIoT‑Consortium Technical Working Group, April 2026. | | Hashing | BLAKE2b‑256 for schema integrity

All components are released under the license, encouraging commercial and academic adoption while preserving openness. 7. Security Evaluation | Threat | Mitigation in SDJS‑217 | |--------|------------------------| | Replay attacks | Schema‑embedded timestamp ( ts ) coupled with nonce‑based AEAD ensures freshness. | | Schema poisoning | Ledger consensus plus ACL prevents unauthorised schema publication; each schema is signed by a known manufacturer key. | | Side‑channel leakage | Constant‑time cryptographic primitives and binary validators eliminate data‑dependent branching. | | Denial‑of‑service (DoS) | Compact binary format caps payload size to 2 KB; nodes can reject unknown schema hashes without decryption. | | Key compromise | Forward‑secure HKDF rotation per schema version limits exposure to a single version. | version 217) is a lightweight