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# Affinidi Trust Registry

[![License: Apache](https://img.shields.io/badge/license-Apache%202.0-blue)](LICENSE)

A high-performance, Rust-based implementation of a Trust Registry, fully compliant with the [Trust Registry Query Protocol (TRQP) v2.0](https://trustoverip.github.io/tswg-trust-registry-protocol/) specification. Built for scalability and reliability, it enables secure, standards-based verification of trusted entities within decentralised identity ecosystems.

## Table of Contents

- [Quickstart]#quickstart
- [What is Trust Registry]#what-is-trust-registry
  - [Why a Trust Registry Matters]#why-a-trust-registry-matters
  - [Sample Use Cases]#sample-use-cases
- [Key Components]#key-components
- [Requirements]#requirements
- [Set up Trust Registry]#set-up-trust-registry
  - [Run with DIDComm Enabled]#run-with-didcomm-enabled
  - [Run with DIDComm Enabled In Private Mode]#run-with-didcomm-enabled-in-private-mode
  - [Run with DIDComm Disabled]#run-with-didcomm-disabled
- [Run Trust Registry on Docker]#run-trust-registry-on-docker
- [Using Redis as Storage Backend]#using-redis-as-storage-backend
  - [Prerequisites]#prerequisites
  - [Setup Redis Storage]#setup-redis-storage
  - [Redis Storage Features]#redis-storage-features
  - [Production Considerations]#production-considerations
  - [Docker Compose with Redis]#docker-compose-with-redis
  - [Migrating from CSV/DynamoDB to Redis]#migrating-from-csvdynamodb-to-redis
  - [Troubleshooting]#troubleshooting
- [Test the API]#test-the-api
  - [Recognition Query]#recognition-query
  - [Authorization Query]#authorization-query
- [Manage Trust Records]#manage-trust-records
- [Embedding the Trust Registry]#embedding-the-trust-registry
  - [Mounting into an existing axum app]#mounting-into-an-existing-axum-app
  - [Driving it from your own transport]#driving-it-from-your-own-transport
  - [DIDComm: who owns the socket]#didcomm-who-owns-the-socket
  - [A lean dependency tree]#a-lean-dependency-tree
  - [What the registry never does to its host]#what-the-registry-never-does-to-its-host
- [Trust Tasks, Transports & Identity]#trust-tasks-transports--identity
  - [Cargo feature flags]#cargo-feature-flags
  - [Trust Task protocol surface]#trust-task-protocol-surface
  - [Identity from a VTA (`vta`)]#identity-from-a-vta-vta
  - [Secret-store backends (`secrets-*`)]#secret-store-backends-secrets-
  - [Embedded fjall storage (`storage-fjall`)]#embedded-fjall-storage-storage-fjall
- [Environment Variables]#environment-variables
  - [Profile Config Options]#profile-config-options
- [Additional Resources]#additional-resources
- [Support \& feedback](#support--feedback)
  - [Reporting technical issues]#reporting-technical-issues
- [Contributing]#contributing
- [Changelog]#changelog

## Quickstart

Get the Trust Registry up and running quickly with default settings (DIDComm disabled).

1. Run the setup command to generate default configurations.

```bash
cargo run --bin setup-trust-registry --features="dev-tools"
```

2. Start the Trust Registry server.

```bash
ENABLE_DIDCOMM=false RUST_LOG=info cargo run --bin trust-registry
```

The Trust Registry will start on `http://localhost:3232` using CSV file storage with sample data from `./sample-data/data.csv`.

3. Test your Trust Registry setup.

```bash
# Query authorization
curl --location 'http://localhost:3232/authorization' \
--header 'Content-Type: application/json' \
--data '{
    "authority_id": "did:example:authority1",
    "entity_id": "did:example:entity1",
    "action": "action1",
    "resource": "resource1"
}'
```

For more details on how to set up and run the Trust Registry, see the [Set up Trust Registry](#set-up-trust-registry) section.

## What is Trust Registry

A **Trust Registry** is a system that maintains and provides authoritative information about which entities, such as organisations, issuers, and verifiers, are authorised to perform specific actions on defined resources within a trust framework. Each entity is identified by its Decentralised Identifier (DID), ensuring cryptographic integrity and interoperability across decentralised identity ecosystems.

### Why a Trust Registry Matters

In decentralised identity and verifiable credentials, verifiers need to answer critical trust questions before accepting or validating credentials, such as:

- "Is this issuer authorised to issue driver's licences?"
- "Is this credential verifier recognised by the appropriate authority?"
- "Can this entity perform a specific action within this trust framework?"

The Trust Registry provides a standardised, queryable database that answers these trust questions by maintaining trust records and their permitted roles within a governance framework.

**Authorisation Queries:** “Has Authority A authorised Entity B to take Action X on Resource Y?”

**Recognition Queries:** "Does Authority X recognise Entity B as an authority to authorise taking Action X on Resource Y?”

The Trust Registry links:

- **Entity IDs** (who) - DIDs representing issuers, verifiers, or other participants.
- **Authority IDs** (governed by whom) - DIDs of governing authorities.
- **Actions** (what) - Operations like "issue", "verify", "revoke".
- **Resources** (on what) - Credential types like "driverlicence", "diploma".
- **Context** - Additional metadata for authorisation decisions.

This ensures **security**, **compliance**, and **interoperability** across decentralised identity systems.

### Sample Use Cases

- **Credential Issuance Verification**

  Verifies whether an issuer is authorised by a government or regulatory body to issue specific credential types (e.g., driver’s licences, professional certifications).

- **Trust Framework Compliance**

  Ensures that all participants in a digital trust ecosystem, such as issuers, verifiers, and relying parties, are recognised and approved by the appropriate governance authorities.

## Key Components

- **`trust-registry`**: Unified server providing both RESTful API (TRQP endpoints for recognition and authorisation queries) and optional DIDComm messaging interface for CRUD admin operations.

- **Storage backends**: Stores authoritative records about the entities for querying. It supports the following storage types:
  - CSV file storage
  - AWS DynamoDB
  - Redis
  - Embedded [fjall]https://github.com/fjall-rs/fjall LSM store (behind the `storage-fjall` feature)

- **Trust Tasks & transports** _(optional)_: Every Trust Registry operation is also modelled as a versioned [Trust Task]https://trusttasks.org (`registry/*`) that verifiers and communities (VTC/OpenVTC) can invoke over DIDComm, HTTP, or TSP. See [Trust Tasks, Transports & Identity]#trust-tasks-transports--identity.

- **VTA identity** _(optional)_: The Trust Registry can source its DID and keys from a [Verifiable Trust Agent]https://docs.affinidi.com instead of a local `PROFILE_CONFIG` (behind the `vta` feature).

## Requirements

1. Install Rust on your machine.

- **Rust**: 1.88.0 or higher
- **Edition**: 2024
- **Cargo**: Latest version bundled with Rust

Verify that your Rust installation meets the requirements.

```bash
rustc --version
cargo --version
```

2. **Required for DIDComm-enabled.** DIDComm mediator instance is required if you want to enable DIDComm for secure trust record management and querying.

To deploy and run a DIDComm mediator, see the [deployment options](https://docs.affinidi.com/products/affinidi-messaging/didcomm-mediator/deployment-options/) page in the documentation.

## Set up Trust Registry

Configure the environment to run Trust Registry. The setup command creates the `.env` file with default configurations. For testing environments, it generates `.env.test` or `.env.pipeline` files with the appropriate test configurations.

### Run with DIDComm Enabled

**Prerequisites:** You must have a running and accessible DIDComm mediator instance before proceeding. The mediator provides the messaging layer for secure communication between administrators, verifiers, and the Trust Registry.

If you don't have a mediator yet, see [deployment options](https://docs.affinidi.com/products/affinidi-messaging/didcomm-mediator/deployment-options/).

To enable DIDComm for managing and querying trust records, run the following command with your mediator's DID:

```bash
cargo run --bin setup-trust-registry --features="dev-tools" -- \
 --mediator-did=<MEDIATOR_DID>
```

The command generates the following:

- Creates a Decentralised Identifier (DID) for the Trust Registry using the **did:peer** method.
- Creates Decentralised Identifiers (DIDs) for test users (Trust Registry and Admin) using the did:peer method.
- Configures the appropriate DIDComm mediator ACLs for the Trust Registry and test user DIDs.
- Populates the environment variables with default values, such as Storage Backend (`csv`) and audit log format (`json`).

### Run with DIDComm Enabled In Private Mode

By default, the Trust Registry runs in **public mode** (`ACL_MODE=ExplicitDeny`), which accepts messages from any DID. To enable **private mode** where only pre-authorized DIDs can send messages to the Trust Registry, use the `--acl-mode=ExplicitAllow` option:

```bash
cargo run --bin setup-trust-registry --features="dev-tools" -- \
 --mediator-did=<MEDIATOR_DID> \
 --acl-mode=ExplicitAllow
```

**With this setup command:**

- Sets the Trust Registry ACL mode to `ExplicitAllow` (private mode).
- Only DIDs in the mediator's allow list for the Trust Registry can send messages (configured via the mediator ACLs during setup).
- Denies all other DIDs, enhancing security for sensitive deployments.

**Use cases for private mode:**

- Production environments that require strict access control.
- Scenarios where only specific administrators should manage trust records.
- Compliance requirements that demand explicit authorisation.

After successful setup, it displays the command to run the Trust Registry.

```bash
RUST_LOG=info cargo run --bin trust-registry
```

### Run with DIDComm Disabled

To configure the Trust Registry without integration with DIDComm, run the following command:

```bash
cargo run --bin setup-trust-registry --features="dev-tools"
```

The command generates the following:

- Populates the environment variables with default values, such as Storage Backend (`csv`) and audit log format (`json`).
- Sets DIDComm-related environment variables to empty values.

After successful setup, it displays the command to run the Trust Registry.

```bash
ENABLE_DIDCOMM=false RUST_LOG=info cargo run --bin trust-registry
```

For more details on setting up the Trust Registry, refer to the [setup guide](https://github.com/affinidi/affinidi-trust-registry-rs/blob/main/SETUP_COMMAND_REFERENCES.md) document.

## Run Trust Registry on Docker

After setting up the Trust Registry, review the Docker settings in `./docker-compose.yaml`. Start the containers using the following command:

```bash
docker compose up --build
```

The Trust Registry will be available at `http://localhost:3232`.

**Note:** The `sample-data` folder is mounted as a volume to synchronise the changes from data.csv to the container automatically. If you have configured a different path for the data using CSV as the storage backend, configure the Docker settings accordingly.

## Using Redis as Storage Backend

Redis is a high-performance, in-memory data store that can be used as a storage backend for Trust Registry. Redis provides fast read/write operations and is ideal for production deployments requiring low-latency access to trust records.

### Prerequisites

- Redis server 5.0 or higher
- Network access to the Redis instance from the Trust Registry

### Setup Redis Storage

1. **Install Redis** (if not already available)

   ```bash
   # macOS
   brew install redis
   
   # Ubuntu/Debian
   sudo apt-get install redis-server
   
   # Docker
   docker run -d -p 6379:6379 redis:7-alpine
   ```

2. **Start Redis** (if installed locally)

   ```bash
   redis-server
   ```

3. **Configure Trust Registry to use Redis**

   Set the following environment variables:

   ```bash
   TR_STORAGE_BACKEND=redis
   REDIS_URL="redis://localhost:6379"
   ```

   For Redis with authentication:

   ```bash
   REDIS_URL="redis://username:password@localhost:6379"
   ```

   For Redis with a specific database:

   ```bash
   REDIS_URL="redis://localhost:6379/0"
   ```

4. **Run Trust Registry**

   ```bash
   ENABLE_DIDCOMM=false RUST_LOG=info cargo run --bin trust-registry
   ```

### Redis Storage Features

- **Fast Operations**: In-memory storage provides sub-millisecond response times
- **Persistence**: Redis can be configured for data persistence using RDB snapshots or AOF (Append Only File)
- **Scalability**: Supports clustering and replication for high availability
- **Data Structure**: Trust records are stored as JSON strings with keys formatted as `entity_id|authority_id|action|resource`

### Production Considerations

For production deployments:

1. **Enable Persistence**: Configure Redis persistence to prevent data loss

   ```bash
   # In redis.conf
   save 900 1
   save 300 10
   save 60 10000
   appendonly yes
   ```

2. **Use Authentication**: Always enable Redis authentication in production

   ```bash
   # In redis.conf
   requirepass your_strong_password
   ```

3. **Configure Memory Limits**: Set appropriate memory limits and eviction policies

   ```bash
   # In redis.conf
   maxmemory 2gb
   maxmemory-policy noeviction
   ```

4. **Use TLS**: For secure connections, use Redis with TLS

   ```bash
   export REDIS_URL="rediss://username:password@host:6380"
   ```

5. **Monitor Performance**: Use Redis monitoring tools to track performance

   ```bash
   redis-cli INFO
   redis-cli MONITOR
   ```

### Docker Compose with Redis

Example `docker-compose.yaml` configuration:

```yaml
version: '3.8'

services:
  redis:
    image: redis:7-alpine
    command: redis-server --requirepass your_password --appendonly yes
    ports:
      - "6379:6379"
    volumes:
      - redis-data:/data
    restart: unless-stopped

  trust-registry:
    build: .
    environment:
      - TR_STORAGE_BACKEND=redis
      - REDIS_URL=redis://:your_password@redis:6379
      - ENABLE_DIDCOMM=false
      - CORS_ALLOWED_ORIGINS=http://localhost:3000
      - AUDIT_LOG_FORMAT=json
    ports:
      - "3232:3232"
    depends_on:
      - redis
    restart: unless-stopped

volumes:
  redis-data:
```

### Migrating from CSV/DynamoDB to Redis

To migrate existing trust records to Redis:

1. Export records from your current storage backend
2. Use the DIDComm admin API to create records in Redis
3. Verify all records are migrated correctly
4. Update the `TR_STORAGE_BACKEND` environment variable to `redis`

### Troubleshooting

**Connection Issues:**
```bash
# Test Redis connectivity
redis-cli -h localhost -p 6379 ping
# Expected output: PONG
```

**View stored records:**
```bash
# List all keys
redis-cli KEYS "*|*|*|*"

# Get a specific record
redis-cli GET "did:example:entity1|did:example:authority1|action1|resource1"
```

**Clear all test data:**
```bash
redis-cli FLUSHDB
```

## Test the API

You can test the Trust Registry by querying the sample data stored in `./sample-data/data.csv`:

### Recognition Query

```bash
curl --location 'http://localhost:3232/recognition' \
--header 'Content-Type: application/json' \
--data '{
    "authority_id": "did:example:authority1",
    "entity_id": "did:example:entity1",
    "action": "action1",
    "resource": "resource1"
}'
```

The API will return whether the specified entity is recognised by the given authority for the requested action and resource.

To query Trust Registry using DIDComm, refer to the [Trust Registry Recognition Query](https://github.com/affinidi/affinidi-trust-registry-rs/blob/main/DIDCOMM_PROTOCOLS.md#query-recognition) protocol.

### Authorization Query

```bash
curl --location 'http://localhost:3232/authorization' \
--header 'Content-Type: application/json' \
--data '{
    "authority_id": "did:example:authority1",
    "entity_id": "did:example:entity1",
    "action": "action1",
    "resource": "resource1"
}'
```

The API will return whether the specified entity is authorised under the given authority for the requested action and resource.

To query Trust Registry using DIDComm, refer to the [Trust Registry Authorization Query](https://github.com/affinidi/affinidi-trust-registry-rs/blob/main/DIDCOMM_PROTOCOLS.md#query-authorization) protocol.

**Testing Tips:**

- Add more records to `./sample-data/data.csv` to expand test coverage.
- Test with both defined and undefined IDs to ensure the system correctly handles invalid or missing identifiers.
- Ensure the `context` field contains a valid JSON object encoded in Base64. Invalid or malformed data should trigger appropriate error responses.

## Manage Trust Records

**Note:** This section applies only when DIDComm is enabled. See [Run with DIDComm Enabled](#run-with-didcomm-enabled) for setup instructions.

You can manage trust records stored in the Trust Registry using DIDComm by sending messages to the Trust Registry's DID. DIDComm provides a secure, interoperable way to exchange messages between an administrator and the Trust Registry, making it ideal for trust record operations such as creating, updating, or querying records.

For a working reference, see the [test-client implementation](https://github.com/affinidi/affinidi-trust-registry-rs/tree/main/test-client), which demonstrates how to build a DIDComm client and send admin operation messages.

See [Trust Registry Administration](https://github.com/affinidi/affinidi-trust-registry-rs/blob/main/DIDCOMM_PROTOCOLS.md#trust-registry-administration) section for more details.

## Embedding the Trust Registry

The Trust Registry runs two ways from the same code: as its own service, or as a
component inside a host application — a VTC, say — that already has an axum
server, a tokio runtime, storage and a mediator connection. Both are supported
first-class; embedding is not a test-only mode.

Everything below is in `trust-registry/examples/embedded_axum.rs`, which is a
complete host application you can run:

```bash
cargo run -p trust-registry --example embedded_axum --no-default-features
```

### Mounting into an existing axum app

```rust
use std::sync::Arc;
use trust_registry::{TrustRegistry, configs::TrustRegistryConfig};
use trust_registry::capabilities::MemoryCapabilityStore;

let registry = TrustRegistry::builder(TrustRegistryConfig::embedded("/srv/app/registry"))
    .repository(my_repository)            // any TrustRecordAdminRepository
    .capability_store(Box::new(MemoryCapabilityStore::default()))
    .dedup_store(my_durable_dedup)        // see the note below
    .shutdown(host_shutdown_token)
    .build()
    .await?;

let app = host_router.nest("/registry", registry.router());
```

`router()` carries the TRQP endpoints, the Trust Tasks HTTPS binding and
`/.well-known/did.json`. It deliberately ships **no CORS layer and no
`/health`** — both belong to the host, and applying ours would override or
collide with theirs. Use `registry.health()` to fold the registry's health into
the host's own endpoint, or `registry.health_router()` for a ready-made one.

`/.well-known/did.json` is only meaningful at the server root, so a host nesting
under a prefix should serve the registry's DID document itself, or mount at `/`.

### Driving it from your own transport

A host that already speaks DIDComm, or anything else, can skip HTTP entirely:

```rust
// A decoded Trust Task from a transport you authenticated yourself.
let outcome = registry.task_handler().handle(doc, Some(sender_did)).await;

// Or, for a DIDComm envelope, letting the registry do the decode and
// §4.8.1 party resolution:
let outcome = registry.route_didcomm_envelope(message.body, &sender_did).await;
```

Pass `None` for the sender when the caller is unauthenticated; writes are then
denied on the admin ACL.

### DIDComm: who owns the socket

The mediator permits **one websocket per DID**. `DidCommSource` says which side
holds it:

| Source                        | Who opens the socket | Use when                                                            |
| ----------------------------- | -------------------- | ------------------------------------------------------------------- |
| `Managed` (default)           | the registry         | the registry's DID is not already connected anywhere else            |
| `SharedAtm { atm, profile }`  | the host, lent over  | the host holds the connection but does not need to keep reading it   |
| `HostDriven`                  | the host, kept       | the host drains the stream itself and routes documents in            |

```rust
let registry = TrustRegistry::builder(config)
    .repository(repo)
    .didcomm_source(DidCommSource::SharedAtm { atm, profile })
    .build()
    .await?;
```

Under `SharedAtm` the host must not still be draining that profile's live
stream — frames go to whichever reader takes them first, so two readers split
the traffic silently. If the host needs to keep reading, use `HostDriven`.

### A lean dependency tree

The standalone service's backends are all default-on. An embedded registry
should turn them off and add back only what it uses:

```toml
[dependencies]
trust-registry = { version = "0.9", default-features = false, features = ["storage-fjall"] }
```

That drops the AWS SDKs, Redis, `serde_dynamo`, `dotenvy`, `crossterm` and
`vti-secrets` — roughly 750 crates down to 620. (`csv` and `clap` still appear,
but transitively via `affinidi-tdk`, not as the registry's own dependencies.)
The example above builds with **no features at all**, using the
dependency-free in-memory `LocalStorage`.

`vti-secrets` in particular is worth leaving off when you can: it is a
workspace member of `verifiable-trust-infrastructure`, so a VTC that enables a
`secrets-*` feature ends up with both its own path copy and a crates.io copy of
that crate (and of `vti-common` beneath it). With no `secrets-*` feature the
registry has no secret store, which is the right shape when the host supplies
the identity — and every shared crate then resolves to exactly one copy.

### What the registry never does to its host

Nothing in the embedded path touches process-global state: it does not read
environment variables (only `configs::Configs::load`, which embedding bypasses,
ever does), install a tracing subscriber, load a `.env` file, or call
`std::process::exit`. Those all live behind the `standalone` feature. Only
`TrustRegistry::serve()` binds a socket, and only when you ask for it.

One default is worth changing deliberately: `dedup_store` falls back to an
in-memory store, which forgets across a restart, so a redelivered mutation could
be applied twice (R1.4). It is the one injection point that changes a
correctness property rather than a convenience — a host with durable storage
should supply its own.

## Trust Tasks, Transports & Identity

Beyond the core REST/DIDComm server, the Trust Registry ships a set of **optional,
feature-gated** capabilities that let Verifiable Trust Communities (VTC/OpenVTC)
and verifiers interact with it as a first-class [Trust Tasks](https://trusttasks.org)
participant, and let it delegate its own identity and secret custody. All of these
are **off by default** — the default build is the REST + DIDComm server described
above.

### Cargo feature flags

| Feature          | Default | Enables                                                                                                                       |
| ---------------- | :-----: | ----------------------------------------------------------------------------------------------------------------------------- |
| `secrets-config` || Inline / plaintext-file secret store for the profile bundle. Pulls `vti-secrets`; with no `secrets-*` feature the registry has no secret store at all. |
| `standalone`     || `server::start()` — the process-owning entrypoint (`.env`, global tracing, `process::exit`). Required by the `trust-registry` binary; an embedded registry does not need it. |
| `storage-csv`    || CSV file storage backend (`TR_STORAGE_BACKEND=csv`, the standalone default).                                                  |
| `storage-ddb`    || DynamoDB storage backend (`TR_STORAGE_BACKEND=dynamodb`).                                                                     |
| `storage-redis`  || Redis storage backend (`TR_STORAGE_BACKEND=redis`).                                                                           |
| `loaders-aws`    || `aws_secrets://` and `aws_parameter_store://` config-loader URI schemes.                                                      |
| `tsp`            |         | [TSP]https://trustoverip.github.io/tswg-tsp-specification/ transport binding for the `registry/*` Trust Tasks.              |
| `vta`            |         | Fetch the Trust Registry DID + keys from a Verifiable Trust Agent at startup; enables the `registry/did/rotate` admin task.   |
| `storage-fjall`  |         | Embedded fjall LSM storage backend for trust records (`TR_STORAGE_BACKEND=fjall`).                                            |
| `secrets-aws`    |         | AWS Secrets Manager backend for the identity secret store.                                                                    |
| `secrets-gcp`    |         | GCP Secret Manager backend.                                                                                                   |
| `secrets-azure`  |         | Azure Key Vault backend.                                                                                                      |
| `secrets-vault`  |         | HashiCorp Vault backend.                                                                                                      |
| `secrets-k8s`    |         | Kubernetes Secret backend.                                                                                                    |
| `secrets-keyring`|         | OS keyring backend.                                                                                                           |
| `secrets-all`    |         | All of the `secrets-*` backends at once.                                                                                      |

Selecting a storage backend that was not compiled in is a startup error naming
the missing feature, never a silent fallback to a different store. The
in-memory `LocalStorage` needs no feature and is always available.

```bash
# Example: build the server with VTA identity, the TSP binding and the AWS secret store
cargo run --bin trust-registry --features "vta,tsp,secrets-aws"
```

### Trust Task protocol surface

Each Trust Registry operation is a versioned Trust Task in the `registry/*` family.
The **same** typed payloads are served over every transport (DIDComm always-on;
HTTP; TSP behind the `tsp` feature), so a VTC can talk to the registry with one
message shape regardless of carrier.

| Trust Task (`slug`)                                   | Kind  | Auth                          |
| ----------------------------------------------------- | ----- | ----------------------------- |
| `registry/recognition/0.1`                            | read  | none (TRQP recognition query) |
| `registry/authorization/0.1`                          | read  | none (TRQP authorization query)|
| `registry/record/query/0.1`                           | read  | none                          |
| `registry/record/put/0.1`                             | write | admin DID + proof             |
| `registry/record/delete/0.1`                          | write | admin DID + proof             |
| `registry/did/rotate/0.1`                             | write | admin DID + proof (`vta` only)|

**Writes** (record mutations and DID rotation) require the sender DID to be in
`ADMIN_DIDS` **and** the Trust Task to carry a Data-Integrity proof. The reads map
verbatim onto the [TRQP v2.0](https://trustoverip.github.io/tswg-trust-registry-protocol/)
recognition/authorization field names, so the plain HTTP TRQP endpoints and the
Trust Task payloads share a single schema.

`registry/record/put` is create-or-replace at the record's four-part key (the
optional `expectedExisting` assertion recovers strict create-only / update-only
semantics); `registry/record/query` is an exact fetch when all four key parts
are supplied and a filtered, cursor-paginated enumeration otherwise. They
supersede the retired `registry/record/{create,update}/0.1` and
`registry/record/{read,list}/0.1` tasks, which this registry no longer accepts.

### Identity from a VTA (`vta`)

With `--features vta`, the Trust Registry authenticates to a Verifiable Trust Agent
at startup and pulls its DID and private keys from a VTA context (remote key
custody) instead of loading a local `PROFILE_CONFIG`. The bundle is cached through
the configured [secret-store backend](#secret-store-backends-secrets-) so the
service can still boot while the VTA is briefly unreachable.

The registry's DID is a VTA-managed `did:webvh`; its keys can be rotated in place
via the `registry/did/rotate/0.1` admin Trust Task (admin-DID + proof gated).

| Variable            | Description                                                                                               | Required                    |
| ------------------- | -------------------------------------------------------------------------------------------------------- | --------------------------- |
| `TR_VTA_CREDENTIAL` | VTA `CredentialBundle` JSON, or a loader URI (`file://`, `aws_secrets://`, …) resolving to it. Its presence enables the VTA path. | Yes (`vta`)   |
| `TR_VTA_CONTEXT_ID` | The VTA context holding this service's DID + keys.                                                        | Yes (`vta`)                 |
| `TR_VTA_URL`        | VTA URL override (otherwise taken from the credential).                                                   | No                          |
| `TR_ALIAS`          | Profile alias. Default `Trust Registry`.                                                                  | No                          |

### Secret-store backends (`secrets-*`)

The `secrets-*` features select where the Trust Registry persists the identity it
custodies (the profile bundle, or — in VTA mode — the offline identity cache).
`secrets-config` (inline / plaintext file) is on by default; cloud, Vault, K8s and
keyring backends are opt-in. Non-interactive self-provisioning mirrors the
mediator-setup and did-hosting tooling, and every backend is configured through
the same shared `vti-secrets` crate the VTA uses — so the config field names line
up one-to-one with the VTA's `[secrets]` table.

**Backend selection** follows the `vti-secrets` priority factory: the first backend
whose feature is compiled in *and* whose activating variable is set wins, in this
order — AWS → GCP → Azure → Vault → Kubernetes `Secret` → config-seed → keyring →
plaintext file. Setting a backend's activating variable (below, in **bold**) is
what turns it on.

The seed / bundle is stored identically (hex-encoded) across every backend, so you
can migrate by copying the value between two vendor CLIs and swapping the
`TR_SECRETS_*` variables.

#### Config-seed / plaintext file (`secrets-config`, default)

| Variable                     | Description                                                                                   |
| ---------------------------- | --------------------------------------------------------------------------------------------- |
| **`TR_SECRETS_SEED`**        | Hex-encoded seed read straight from the environment (config-seed). Its presence activates it. |
| `TR_SECRETS_ALLOW_PLAINTEXT` | Set `true` to permit the plaintext-file fallback (`<data_dir>/seed.hex`). **Dev/test only.**  |
| `TR_SECRETS_DATA_DIR`        | On-disk directory for file-backed backends. Default `./.trust-registry`.                      |

#### AWS Secrets Manager (`secrets-aws`)

| Variable                       | Description                                                                                      |
| ------------------------------ | ------------------------------------------------------------------------------------------------ |
| **`TR_SECRETS_AWS_SECRET_NAME`** | Secrets Manager secret name/ARN. Activates the backend. Credentials from the standard SDK chain. |
| `TR_SECRETS_AWS_REGION`        | Region override. Falls back to `AWS_REGION` / IMDS.                                               |

First-boot provisioning needs `secretsmanager:CreateSecret`; steady state needs only
`GetSecretValue` + `PutSecretValue`.

#### GCP Secret Manager (`secrets-gcp`)

| Variable                        | Description                                                              |
| ------------------------------- | ------------------------------------------------------------------------ |
| **`TR_SECRETS_GCP_SECRET_NAME`** | Secret Manager secret name. Activates the backend.                       |
| `TR_SECRETS_GCP_PROJECT`        | GCP project ID. Auth via Application Default Credentials / Workload Identity. |

#### Azure Key Vault (`secrets-azure`)

| Variable                          | Description                                                                      |
| --------------------------------- | -------------------------------------------------------------------------------- |
| **`TR_SECRETS_AZURE_VAULT_URL`**  | Key Vault URL, e.g. `https://my-vault.vault.azure.net`. Activates the backend.    |
| `TR_SECRETS_AZURE_SECRET_NAME`    | Secret name. Auth via the DefaultAzureCredential chain (Managed Identity, etc.).  |

#### HashiCorp Vault (`secrets-vault`)

Stores the seed as a field in a KV v2 secret. Designed for in-cluster Kubernetes but
works anywhere; the Vault token is auto-renewed in the background. Three auth methods,
chosen by `TR_SECRETS_VAULT_AUTH_METHOD` (**default `kubernetes`**). The canonical
`VAULT_ADDR` / `VAULT_NAMESPACE` / `VAULT_TOKEN` / `VAULT_SKIP_VERIFY` names are
honoured too (they take precedence over the `TR_SECRETS_VAULT_*` spelling), so the
same Vault env carries across services.

| Variable                            | Description                                                                                          |
| ----------------------------------- | ---------------------------------------------------------------------------------------------------- |
| **`TR_SECRETS_VAULT_ADDR`** (or `VAULT_ADDR`) | Vault server URL. Activates the backend.                                                   |
| `TR_SECRETS_VAULT_SECRET_PATH`      | KV v2 path under the mount, e.g. `tr/master-seed`. **Required** once `..._ADDR` is set.              |
| `TR_SECRETS_VAULT_KV_MOUNT`         | KV v2 mount. Default `secret`. (No `/data/` segment — vaultrs injects it.)                           |
| `TR_SECRETS_VAULT_SECRET_KEY`       | Field within the secret holding the hex seed. Default `seed`.                                        |
| `TR_SECRETS_VAULT_NAMESPACE` (or `VAULT_NAMESPACE`) | Vault Enterprise namespace, if any.                                                   |
| `TR_SECRETS_VAULT_AUTH_METHOD`      | `kubernetes` (default), `token`, or `approle`.                                                       |
| `TR_SECRETS_VAULT_K8S_ROLE`         | Kubernetes auth role. **Required for the `kubernetes` method** (the default — startup errors without it). |
| `TR_SECRETS_VAULT_K8S_MOUNT`        | Kubernetes auth mount. Default `kubernetes`.                                                         |
| `TR_SECRETS_VAULT_K8S_JWT_PATH`     | ServiceAccount JWT path. Default `/var/run/secrets/kubernetes.io/serviceaccount/token`.             |
| `VAULT_TOKEN` (or `TR_SECRETS_VAULT_TOKEN`) | Static token for the `token` method. Prefer the env var over config.                        |
| `TR_SECRETS_VAULT_APPROLE_ROLE_ID`  | AppRole `role_id` for the `approle` method.                                                          |
| `TR_SECRETS_VAULT_APPROLE_SECRET_ID`| AppRole `secret_id` for the `approle` method.                                                        |
| `TR_SECRETS_VAULT_APPROLE_MOUNT`    | AppRole mount. Default `approle`.                                                                    |
| `TR_SECRETS_VAULT_SKIP_VERIFY` (or `VAULT_SKIP_VERIFY`) | Disable TLS verification. **Dev/test only.**                                     |

Minimal in-cluster (Kubernetes auth) env — this is the common case, and the two that
were previously impossible to set from the environment are the auth method and role:

```bash
TR_SECRETS_VAULT_ADDR=https://vault.svc.cluster.local:8200
TR_SECRETS_VAULT_SECRET_PATH=tr/master-seed
TR_SECRETS_VAULT_AUTH_METHOD=kubernetes     # default; shown for clarity
TR_SECRETS_VAULT_K8S_ROLE=trust-registry    # required for kubernetes auth
```

Vault server side (one-time): enable the `kubernetes` auth method, write
`auth/kubernetes/config`, bind the registry's ServiceAccount to a policy granting
`read`/`create`/`update` on `secret/data/tr/master-seed`, and create the role named
above with matching `bound_service_account_names` / `bound_service_account_namespaces`.

#### Kubernetes `Secret` (`secrets-k8s`)

Native namespaced `Secret`, no extra infra. Credentials resolve from the pod's mounted
ServiceAccount in-cluster, or your kubeconfig when running `setup` out-of-cluster.

| Variable                       | Description                                                                                     |
| ------------------------------ | ----------------------------------------------------------------------------------------------- |
| **`TR_SECRETS_K8S_SECRET_NAME`** | `Secret` name holding the hex seed. Activates the backend.                                       |
| `TR_SECRETS_K8S_NAMESPACE`     | Namespace. Unset ⇒ the pod's own namespace in-cluster (inject via Downward API), else `default`. |
| `TR_SECRETS_K8S_SECRET_KEY`    | Key within the `Secret`'s `data`. Default `seed`.                                               |

RBAC: the ServiceAccount needs `get` (+ `create`/`update` for first-boot / re-key) on the
`Secret`. A bare `Secret` is only base64-encoded in etcd — enable encryption-at-rest (or
use Vault / a cloud manager) before treating this as production-grade.

#### OS keyring (`secrets-keyring`)

| Variable                     | Description                                                                          |
| ---------------------------- | ------------------------------------------------------------------------------------ |
| `TR_SECRETS_KEYRING_SERVICE` | OS-native credential-store service name. Set a distinct value per co-located instance. |

Interactive on macOS (Keychain unlock prompt) — use a different backend for headless / CI.

### Embedded fjall storage (`storage-fjall`)

With `--features storage-fjall` and `TR_STORAGE_BACKEND=fjall`, trust records are
stored in an embedded [fjall](https://github.com/fjall-rs/fjall) LSM store — a
single-node, on-disk option that needs no external database.

| Variable         | Description                                                | Required                                       |
| ---------------- | ---------------------------------------------------------- | ---------------------------------------------- |
| `TR_FJALL_PATH`  | Directory for the embedded fjall keyspace.                 | Required when `TR_STORAGE_BACKEND` = `fjall`   |

## Environment Variables

See the list of environment variables and their usage.

| Variable Name           | Description                                                                                                                                                                               | Required                                     |
| ----------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------- |
| `TR_STORAGE_BACKEND`    | Storage backend for trust records. Options: `csv`, `ddb`, `redis`, and `fjall` (with the `storage-fjall` feature).                                                                        | Yes                                          |
| `FILE_STORAGE_PATH`     | Path to the CSV file when using CSV as the storage backend.                                                                                                                               | Required when `TR_STORAGE_BACKEND` = `csv`   |
| `DDB_TABLE_NAME`        | DynamoDB table name for storing trust records when using DDB as the storage backend.                                                                                                      | Required when `TR_STORAGE_BACKEND` = `ddb`   |
| `REDIS_URL`             | Redis connection URL when using Redis as the storage backend. Format: `redis://host:port` or `redis://username:password@host:port/db`.                                                    | Required when `TR_STORAGE_BACKEND` = `redis` |
| `CORS_ALLOWED_ORIGINS`  | Comma-separated list of allowed URLs for CORS.                                                                                                                                            | Yes                                          |
| `AUDIT_LOG_FORMAT`      | Output format for audit logs. Options: `text`, `json`.                                                                                                                                    | Yes                                          |
| `MEDIATOR_DID`          | Decentralised Identifier (DID) of the DIDComm mediator used as a transport layer for managing trust records.                                                                              | Required when DIDComm is enabled             |
| `ADMIN_DIDS`            | Comma-separated list of DIDs authorised to manage trust records in the Trust Registry.                                                                                                    | Required when DIDComm is enabled             |
| `PROFILE_CONFIG`        | Trust Registry DID and DID secrets for DIDComm communication. See [Profile Config Options]#profile-config-options for configuration formats. **_Sensitive information, do not share._** | Required when DIDComm is enabled             |
| `ACL_MODE` | ACL Mode for Trust Registry when DIDComm is enabled. ExplicitDeny - public mode, ExplicitAllow - private mode                                                                                                          | default: `ExplicitDeny`                             |
| `TR_PUBLIC_URL`         | Externally reachable base URL of the REST/TRQP surface (e.g. `https://registry.example.org`). When set, the generated DID document advertises a `TRQPRest` service entry so peers can discover the REST endpoint by resolving the registry's DID. Must be `https://` (loopback `http://` allowed for local dev). Unset ⇒ REST is still served, but not advertised. | No                                           |
| `ENABLE_REST`           | Serve TRQP over REST and advertise `TRQPRest` (needs `TR_PUBLIC_URL` to be advertised).                                                                                                    | default: `true`                              |
| `ENABLE_DIDCOMM`        | Run the DIDComm listener and advertise `DIDCommMessaging`.                                                                                                                                | default: `true`                              |
| `ENABLE_TSP`            | Route multiplexed TSP frames and advertise `TSPTransport`. Requires `ENABLE_DIDCOMM=true` and a binary built with `--features tsp`.                                                        | default: `false`                             |

### Transport selection

`ENABLE_REST`, `ENABLE_DIDCOMM` and `ENABLE_TSP` each govern **both** halves of a
transport: whether it is served, and whether the DID document advertises it. A
single flag per protocol is deliberate — a registry that advertises a service
entry nothing answers sends clients to a dead endpoint, and `trql-client`
refuses to silently downgrade to another transport when the selected one fails.

Rules enforced at startup (and by `setup_trust_registry` when generating the
DID document, which reads the same flags):

- **At least one transport must be enabled.** All three `false` is refused.
- **`ENABLE_TSP=true` requires `ENABLE_DIDCOMM=true`.** TSP frames are
  multiplexed onto the DIDComm mediator socket — the mediator permits one
  websocket per DID — so there is no TSP-only receive loop.
- **`ENABLE_TSP=true` requires `--features tsp`.** A runtime flag cannot enable
  a compiled-out binding; the build fails startup rather than advertise TSP.
- **`ENABLE_REST=true` without `TR_PUBLIC_URL`** serves REST but does not
  advertise it, and warns at startup. The bind address in `LISTEN_ADDRESS` is
  not a fallback: it is frequently `0.0.0.0`.

The DIDComm and TSP service endpoints both carry the **mediator DID**, not a
URL — the transport URL lives in the mediator's own DID document. REST carries
its URL directly.

> **Note:** with `ENABLE_DIDCOMM=false` no DID document is built at all, since
> the registry's DID profile is loaded on the DIDComm path. A REST-only registry
> is reached by URL rather than by resolving its DID.

### Profile Config Options

The `PROFILE_CONFIG` environment variable uses a URI-based loader that supports multiple configuration options. The loader allows you to store DID and DID secrets securely according to your deployment requirements.

| Scheme              | Format                                                    | Description                                                                                                               |
| ------------------- | --------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------- |
| Direct Value        | `PROFILE_CONFIG='<JSON_STRING>'`                          | Store the configuration directly as an inline JSON string in the environment variable. Recommended for local development. |
| String Protocol     | `PROFILE_CONFIG='string://<JSON_STRING>'`                 | Explicitly specify the value as a string literal. Same functionality as the direct value option.                          |
| File System         | `PROFILE_CONFIG='file://path/to/config.json'`             | Load configuration from a JSON file on the local filesystem. The path must be accessible by the application.              |
| AWS Secrets Manager | `PROFILE_CONFIG='aws_secrets://<SECRET_NAME>'`            | Retrieve configuration from AWS Secrets Manager. The secret value must be stored in plaintext format as a JSON string.    |
| AWS Parameter Store | `PROFILE_CONFIG='aws_parameter_store://<PARAMETER_NAME>'` | Load configuration from AWS Systems Manager Parameter Store. The parameter value must be a JSON string.                   |

**Expected Value:**

All options must provide the Trust Registry DID and DID secrets in the following JSON structure:

```json
{
  "alias": "Trust Registry",
  "did": "did:peer:2.VzDna...",
  "secrets": [
    {
      "id": "did:peer:2.VzDna...#key-1",
      "privateKeyJwk": {
        "crv": "P-256",
        "kty": "EC",
        "x": "RgvVBx01Mva...",
        "y": "U5pT2A5WdIkD..."
      },
      "type": "JsonWebKey2020"
    },
    {
      "id": "did:peer:2.VzDna...#key-2",
      "privateKeyJwk": {
        "crv": "secp256k1",
        "d": "...",
        "kty": "EC",
        "x": "O9pWQXY...",
        "y": "TQk8LY_BcY..."
      },
      "type": "JsonWebKey2020"
    }
  ]
}
```

**Examples:**

```bash
# Direct value (local development)
PROFILE_CONFIG='{"alias":"Trust Registry","did":"did:peer:2.VzDna...","secrets":[...]}'

# File-based configuration
PROFILE_CONFIG='file:///etc/trust-registry/config.json'

# AWS Secrets Manager
PROFILE_CONFIG='aws_secrets://prod/trust-registry/profile'

# AWS Parameter Store
PROFILE_CONFIG='aws_parameter_store:///trust-registry/profile'
```

**Note:** If no URI scheme is specified, the loader parses the value as a direct string literal by default.

## Additional Resources

- [DIDComm Protocols Used]https://github.com/affinidi/affinidi-trust-registry-rs/blob/main/DIDCOMM_PROTOCOLS.md
- [Trust Registry Setup Guide]https://github.com/affinidi/affinidi-trust-registry-rs/blob/main/SETUP_COMMAND_REFERENCES.md

## Support & feedback

If you face any issues or have suggestions, please don't hesitate to contact us using [this link](https://share.hsforms.com/1i-4HKZRXSsmENzXtPdIG4g8oa2v).

### Reporting technical issues

If you have a technical issue with the project's codebase, you can also create an issue directly in GitHub.

1. Ensure the bug was not already reported by searching on GitHub under
   [Issues]https://github.com/affinidi/affinidi-trust-registry-rs/issues.

2. If you're unable to find an open issue addressing the problem,
   [open a new one]https://github.com/affinidi/affinidi-trust-registry-rs/issues/new.
   Be sure to include a **title and clear description**, as much relevant information as possible,
   and a **code sample** or an **executable test case** demonstrating the expected behaviour that is not occurring.

## Contributing

Want to contribute?

Head over to our [CONTRIBUTING](https://github.com/affinidi/affinidi-trust-registry-rs/blob/main/CONTRIBUTING.md) guidelines.

## Changelog

See [CHANGELOG](./CHANGELOG.md) for release notes.