SAIHM (Sovereign AI Horizontal Memory) This document defines the Sovereign AI Horizontal Memory (SAIHM) protocol, a memory layer for AI agents that supports post-quantum identity binding, public-chain audit anchoring, per-cell encryption with wallet-derived keys, revocable sharing contracts, and cryptographic right-to-erasure aligned with Article 17 of EU Regulation 2016/679 (GDPR). SAIHM is the memory-layer protocol companion to the Model Context Protocol (MCP). MCP standardizes how AI agents reach tools and contextual data sources; SAIHM standardizes how AI agents persist, share, and erase memory across sessions, models, and vendors.