# Glossary

> Terms and acronyms used throughout Attestix documentation

## A

**A2A (Agent-to-Agent Protocol)** - Google's open protocol for agent interoperability. Agents publish JSON Agent Cards at `/.well-known/agent.json` describing their capabilities. Attestix can generate and parse these cards.

**Agent Card** - A JSON document describing an AI agent's name, capabilities, URL, and version. Follows the A2A specification. Hosted at a well-known URL for discovery.

**Attestation** - A cryptographically signed statement about a fact. In Attestix, attestations include identity tokens, compliance declarations, and credential proofs.

## B

**Base L2** - A Layer 2 Ethereum rollup built by Coinbase. Attestix anchors to Base L2 testnet (Sepolia) today via EAS due to sub-$0.01 gas costs and fast finality. Mainnet schema registration is planned for a future release.

**Batch Anchoring** - Combining multiple attestation hashes into a single Merkle tree and anchoring only the root hash on-chain. Reduces cost by up to 100x compared to individual anchoring.

## C

**Chain Hash** - A SHA-256 hash linking each audit trail entry to the previous entry. Creates a tamper-evident log where altering any entry invalidates all subsequent hashes.

**Conformity Assessment** - An evaluation of whether an AI system meets EU AI Act requirements. Can be self-assessment (limited-risk) or third-party (high-risk via notified bodies).

## D

**DID (Decentralized Identifier)** - A W3C standard for globally unique identifiers that do not require a central registry. Attestix supports `did:key` (ephemeral, no network needed) and `did:web` (domain-hosted).

**DID Document** - A JSON-LD document associated with a DID containing public keys, authentication methods, and service endpoints.

**Declaration of Conformity** - An Annex V document under the EU AI Act declaring that an AI system meets all applicable requirements. Attestix generates this as a W3C Verifiable Credential.

## E

**EAS (Ethereum Attestation Service)** - An open protocol for creating on-chain attestations on Ethereum and L2 networks. Attestix uses EAS on Base L2 testnet for tamper-evident anchoring.

**Ed25519** - An elliptic curve digital signature algorithm (RFC 8032). Attestix uses Ed25519 for signing all identity tokens, credentials, and audit entries. Fast, compact, and quantum-aware.

**Ed25519Signature2020** - A linked data proof type using Ed25519 signatures. Used in Attestix's W3C Verifiable Credentials.

**EU AI Act** - Regulation (EU) 2024/1689 establishing harmonized rules for AI systems in the European Union. Transparency enforcement begins August 2, 2026.

## G

**GDPR Article 17** - The "right to erasure" (right to be forgotten). Attestix has local erasure tooling for managed records and parseable local backups. Remote copies, prior exports and shared credentials require separate handling. Deletion is not cryptographic proof of GDPR conformity.

## H

**High-Risk AI System** - An AI system classified under EU AI Act Annex III as requiring conformity assessment, registration, and ongoing monitoring. Examples: medical diagnosis, credit scoring, law enforcement.

## J

**JCS (JSON Canonicalization Scheme)** - RFC 8785. A deterministic JSON serialization method ensuring the same data always produces the same byte sequence. Required for consistent signature verification.

**JWT (JSON Web Token)** - A compact, URL-safe token format. Attestix uses JWT for UCAN delegation tokens.

## M

**MCP (Model Context Protocol)** - Anthropic's protocol for connecting AI models to external tools and data sources. Attestix is implemented as an MCP server exposing MCP tools.

**Merkle Tree** - A hash tree where each leaf is a hash of a data block and each non-leaf node is a hash of its children. Used in batch anchoring to efficiently anchor multiple attestations in a single transaction.

**Multibase** - A self-describing base encoding format. Attestix uses multibase-encoded public keys (e.g., `z6Mk...` for base58btc-encoded Ed25519 keys).

## N

**Notified Body** - An organization accredited by an EU member state to conduct third-party conformity assessments for high-risk AI systems.

## P

**PBKDF2** - Password-Based Key Derivation Function 2. Used internally for deterministic key generation from passphrases.

**Provenance** - The documented history of an AI system's training data sources, model lineage, and decision-making process. Required by EU AI Act Articles 10, 11, and 12.

## R

**Reputation Score** - A normalized 0.0-1.0 trust score calculated from an agent's verified interactions. Uses recency-weighted averaging (more recent interactions have higher weight).

**Risk Category** - EU AI Act classification: unacceptable (banned), high (Annex III, requires conformity assessment), limited (transparency obligations), or minimal (voluntary codes).

## S

**Schema UID** - A unique identifier for an EAS attestation schema on-chain. Attestix uses a specific schema UID for its blockchain-anchored attestations.

## U

**UAIT (Unified Agent Identity Token)** - Attestix's core identity primitive. A signed JSON document containing an agent's ID, capabilities, DID, metadata, and Ed25519 signature. Bridges MCP OAuth, A2A, and DID ecosystems.

**UCAN (User Controlled Authorization Networks)** - A decentralized authorization protocol using chained JWTs. Attestix implements UCAN v0.9.0 for capability delegation between agents with time-bounded, scope-limited permissions.

## V

**VC (Verifiable Credential)** - A W3C standard for tamper-evident, cryptographically verifiable claims. Attestix issues VCs with Ed25519Signature2020 proofs for compliance declarations, identity attestations, and custom claims.

**VP (Verifiable Presentation)** - A W3C standard for bundling one or more VCs into a signed package for a specific verifier. Includes a challenge-response mechanism to prevent replay attacks.