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Distributed Compliance Ledger

License Unit Tests

If you are interested in how to build and run the project locally, please look at README-DEV

Please note, that the only officially supported platform now is Linux. It's recommended to develop and deploy the App on Ubuntu 18.04 or Ubuntu 20.04.

Overview

DC Ledger is a public permissioned Ledger which can be used for two main use cases:

  • ZB/Matter compliance certification of device models
  • Public key infrastructure (PKI)

More information about use cases can be found in DC Ledger Overview and Use Case Diagrams.

DC Ledger is based on CometBFT and Cosmos SDK.

DC Ledger is a public permissioned ledger in the following sense:

In order to send write transactions to the ledger you need:

  • Have a private/public key pair
  • Have an Account created on the ledger via ACCOUNT transaction (see Use Case Txn Auth).
    • The Account stores the public part of the key
    • The Account has an associated role. The role is used for authorization policies.
  • Sign every transaction by the private key.

Main Components

Pool of Nodes

  • A network of CometBFT-based validator nodes (Validators and Observers) maintaining the ledger.
  • Every validator node (dcld binary) runs DC Ledger application code (based on Cosmos SDK) implementing the use cases.
  • See the proposed deployment in deployment and deployment-detailed.
  • See recommended design for DCL MainNet deployment on AWS in aws deployment

Node Types

  • Full Node: contains a full replication of data (ledger, state, etc.):
    • Validator Node (VN): a full node participating in consensus protocol (ordering transactions).
    • Sentry Node: a full node that doesn't participate in consensus and wraps the validator node representing it for the rest of the network as one of the ways for DDoS protection.
      • Private Sentry Node: a full node to connect other Validator or Sentry nodes only; should not be accessed by clients.
      • Public Sentry Node: a full node to connect other external full nodes (possibly observer nodes).
    • Observer Node (ON): a full node that doesn't participate in consensus. Should be used to receive read/write requests from the clients.
  • Light Client Proxy Node: doesn't contain a full replication of data. Can be used as a proxy to untrusted Full nodes for single-value query requests sent via CLI or CometBFT RPC. It will verify all state proofs automatically.
  • Seed Node: provides a list of peers which a node can connect to.

See

Clients

For interactions with the pool of nodes (sending write and read requests).

Every client must be connected to a Node (either Observer or Validator).

If there is no trusted node for connection, a Light Client Proxy can be used. A Light Client Proxy can be connected to multiple nodes and will verify the state proofs for every single value query request.

Please note, that multi-value queries don't have state proofs support and should be sent to trusted nodes only.

Please make sure that TLS is enabled in gRPC, REST or Light Client Proxy for secure communication with a Node.

How To: Node Operators

Add an Observer node to existing network

See Running Node. There are two options to add an Observer nodes:

Please take into account running-node-in-existing-network.md.

Add a Validator node to existing network

A recommended way for deployment and client connection: diagram, diagram-detailed and diagram-aws.

See Running Node for possible patterns and instructions.

Please take into account running-node-in-existing-network.md.

Upgrade all nodes in a pool to a new version of DCL application

DCL application can be simultaneously updated on all nodes in the pool without breaking consensus. See Pool Upgrade and Pool Upgrade How To for details.

Run a local pool of nodes in Docker

This is for development purposes only.

See Run local pool section in README-DEV.md.

How To: Users

CLI

  • The same dcld binary as a Node
  • A full list of all CLI commands can be found there: transactions.md.
  • CLI can be used for write and read requests.
  • Please configure the CLI before using (see how-to.md).
  • If there are no trusted Observer or Validator nodes to connect a CLI, then a Light Client Proxy can be used.

Light Client Proxy

Should be used if there are no trusted Observer or Validator nodes to connect.

It can be a proxy for CLI or direct requests from code done via CometBFT RPC.

Please note, that CLI can use a Light Client proxy only for single-value query requests. A Full Node (Validator or Observer) should be used for multi-value query requests and write requests.

Please note, that multi-value queries don't have state proofs support and should be sent to trusted node only.

See Run Light Client Proxy for details how to run it.

REST

gRPC

CometBFT RPC and Light Client

  • CometBFT RPC is exposed by every running node at port 26657. See https://docs.cosmos.network/v0.47/learn/advanced/grpc_rest#cometbft-rpc.
  • CometBFT RPC supports state proofs. CometBFT's Light Client library can be used to verify the state proofs. So, if Light Client API is used, then it's possible to communicate with non-trusted nodes.
  • Please note, that multi-value queries don't have state proofs support and should be sent to trusted nodes only.
  • There are currently no DC Ledger specific API libraries for various platforms and languages, but they may be provided in the future.
  • The following libraries can be used as light clients:
  • Refer to this doc to see how to subscribe to a CometBFT WebSocket based events and/or query an application components.

Instructions

After the CLI or REST API is configured and Account with an appropriate role is created, the following instructions from how-to.md can be used for every role (see Use Case Diagrams):

  • Trustee
    • propose new accounts
    • approve/reject new accounts
    • propose revocation of accounts
    • approve revocation of accounts
    • propose X509 root certificates
    • approve/reject X509 root certificates
    • propose revocation of X509 root certificates
    • approve revocation of X509 root certificates
    • propose pool upgrade
    • approve/reject pool upgrade
    • propose disable a validator node
    • approve/reject disable a validator node
  • Vendor
    • publish/update vendor info
    • publish/update/delete device model info
    • publish/update/delete device model version
    • publish/update/delete PKI Revocation Distribution Point
    • publish/remove X509 certificates
  • Certification Center
    • certify or revoke certification of device models
    • update/delete compliance info
  • Vendor Admin
    • publish/update vendor info for any vendor
  • Node Admin
    • add a new Validator node
    • disable a Validator node
    • enable a Validator node

Useful Links