AIKernel Hash-Anchored Trust Layer (HATL): A Hybrid Symmetric Ledger with Hash-Based Public Anchors

This technical note introduces the AIKernel Hash-Anchored Trust Layer (HATL), a hybrid trust architecture for Semantic Context Operating Systems and autonomous AI runtimes. HATL separates the trust boundary into an inner high-frequency symmetric ledger and an outer publicly auditable anchoring layer. The inner layer uses HMAC-SHA-512 and HKDF-based forward ratcheting to bind ReplayLogs, execution outcomes, and capability states with low runtime overhead. The outer layer aggregates local ledger commitments into Merkle roots and periodically anchors them using hash-based public signature mechanisms such as LMS, XMSS, and SLH-DSA. The report is distributed as a three-part technical package. Part I contains the full English manuscript and is the canonical version. Part II contains technical appendices, repository specifications, schemas, and reference implementation artifacts. Part III contains the Japanese companion translation. This version incorporates review-driven clarifications on secure erasure in C# / .NET environments, fail-closed handling of indeterminate governance decisions, and future integration of zero-knowledge proof techniques for public anchor verification. Documents are licensed under CC BY 4.0. Code, schemas, and contract specimens included in the appendices are provided under Apache-2.0.