Core Concepts
Event
An event is a single recorded fact. It represents something that occurred at a point in time.
Examples:
- A model produced an output
- A policy version was applied
- A decision was recorded
ChainOfFact does not interpret events.
Append-Only Ledger
Events are written once and never modified or deleted.
Each event links cryptographically to the previous event.
Absence
If a field or event was not recorded, it is considered UNKNOWN.
ChainOfFact does not infer missing information.
Verification
Verification recomputes hashes from stored data and compares them to recorded values.
Verification does not require trusting ChainOfFact.
Direct Answer
ChainOfFact is built on four core concepts: append-only ledger, SHA-256 hashing, Ed25519 signature verification, and a discrete four-state proof model.
Append-Only Ledger
The fact ledger accepts only INSERT operations. No UPDATE or DELETE is permitted at any layer. A rolling ledger root hash represents the state of the entire fact chain at any point in time.
Cryptographic Hashing
Each fact is identified by a SHA-256 hash computed from ten canonical fields using deterministic serialization (sorted keys, UTF-8 encoding). The hash is computed at ingestion and never recomputed.
Fact Chain Integrity
Each fact includes the hash of the previous fact, creating a cryptographic chain. Tampering with any fact breaks the chain. The verifyFactChain endpoint checks the entire chain in a single call.