# Aqua Protocol

> Aqua is an open-source cryptographic protocol for verifiable, portable data trees: typed objects, templates, signatures, anchors, and selective disclosure — tamper-evident provenance without requiring a blockchain.

## Status

Aqua Protocol v4 is experimental and under active development. The published components — `aqua-rs-sdk-core` (protocol core) and `aqua-template-registry` (template distribution) — are an early community release with a deliberately limited functionality scope. Version numbers have not yet been increased, backward compatibility is not yet provided, and breaking changes are expected and may occur without notice. The full `aqua-rs-sdk` (WASM compute runtime, policy engine, daemon runtime, timestamping providers) is scheduled for a later publication. Aqua v3 (JavaScript SDK) remains the stable production release.

## Core Concepts

- **Aqua Tree**: a portable JSON structure of hash-linked revisions (`revisions` map keyed by multihash, plus an unhashed organizational `file_index`).
- **Revision kinds (4)**: Object (typed payloads), Template (JSON Schema type definitions; the template hash is the type identity), Signature (Ed25519, Ethereum EIP-191, ECDSA P-256, WebAuthn P-256; signers identified by DID), Anchor (structural and compositional links between revisions and trees).
- **Methods**: `scalar` (compact canonical JSON hash) or `tree` (Merkle-hashed fields, enabling field-level selective disclosure).
- **Verification**: staged, fail-closed pipeline with policies (`strict`, `offline`, `debug`); outcomes are verified / verified_with_warnings / failed.
- **Wire schema version**: every v4 revision carries `"version": "https://aqua-protocol.org/docs/v4/schema"`; that URL resolves to the protocol reference.

## Published Components

- aqua-rs-sdk-core (Rust, Apache-2.0): https://github.com/inblockio/aqua-rs-sdk-core — install via git dependency: `aqua-rs-sdk-core = { git = "https://github.com/inblockio/aqua-rs-sdk-core" }` (not yet on crates.io). Normative protocol specification: https://github.com/inblockio/aqua-rs-sdk-core/tree/main/protocol-specification
- aqua-template-registry (Rust, Apache-2.0): https://github.com/inblockio/aqua-template-registry — publisher-DID scoped template distribution; hosted instance (no SLA, experimental): https://aqua-registry.inblock.io

## Key Links

- Documentation: https://aqua-protocol.org/docs/v4.0.0/welcome
- Quickstart (Rust): https://aqua-protocol.org/docs/v4.0.0/quickstart
- Core Concepts: https://aqua-protocol.org/docs/v4.0.0/concepts
- Protocol Reference: https://aqua-protocol.org/docs/v4.0.0/schema-reference/introduction
- SDK Onboarding: https://aqua-protocol.org/docs/v4.0.0/dev-tools/sdk-core
- Template Registry: https://aqua-protocol.org/docs/v4.0.0/dev-tools/template-registry
- Audit Trails for AI Agents: https://aqua-protocol.org/docs/v4.0.0/dev-tools/agent-audit-trails
- Release Status & Versioning: https://aqua-protocol.org/docs/v4.0.0/version-info
- Use Cases: https://aqua-protocol.org/docs/v4.0.0/use-cases/introduction
- GitHub: https://github.com/inblockio

## For AI Agents

Aqua v4 ships an audit-trail template family (11 data-only templates: user turn marker, user prompt, agent reasoning, tool call, attested API response, tool result, human approval, agent response, round anchor, session close) for recording what an agent did during a session as signed, verifiable, selectively disclosable Aqua trees. Start at https://aqua-protocol.org/docs/v4.0.0/dev-tools/agent-audit-trails

## Documentation Versions

- v4.0.0 (experimental, active): https://aqua-protocol.org/docs/v4.0.0/welcome
- v3.0.2 (stable): https://aqua-protocol.org/docs/v3.0.2/introduction
- v2.0.2: https://aqua-protocol.org/docs/v2.0.2/introduction
- v1.1.0: https://aqua-protocol.org/docs/v1.1.0/introduction

## Organization

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