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The Veres One DID Method

Contributors: Manu Sporny, David Longley, and Chris Webber

Abstract

The Veres One Blockchain is a public, permissionless ledger designed specifically for the creation and management of Decentralized Identifiers. Veres One DIDs are self-administered identifiers that may be used by people, organizations, and digital devices to establish an identifier that is under their control. Veres One DIDs are useful in ecosystems where one needs to issue, store, and use Verifiable Credentials.

The Veres One DID Method Specification details how developers may create, update, and verify Veres One DIDs.

Introduction

The Veres One Blockchain is a fit-for-purpose blockchain built specifically for Decentralized Identifiers. This specialization enables the blockchain to be faster, more cost effective, and more privacy enhancing compared to existing blockchains that are being repurposed for identity management. The Veres One Ecosystem is:

  • Public - Anyone in the world may read and audit the entire contents of the ledger.

  • Permissionless - Any person or organization in the world may create and control their identifiers.

  • Leaderless - Blockchain consensus relies on leaderless elector collaboration, not proof of work, to determine when consensus has been finalized. Electors are selected dynamically to allow participants to join and leave the network and to ensure that there is no centralization or single point of failure for the ledger.

  • **Based entirely on open standards and open specifications **- Broad implementation and interoperability can only be achieved if all aspects of the system are documented and standardized in a non-discriminatory, patent-free and royalty-free manner while ensuring that the creators and maintainers of the system are properly funded.

  • Built on a stakeholder driven governance model - The source code and development team have a strict mission-driven focus that always puts the users of the ledger first.

  • Economically sustainable - The people that create, run, and protect the network are paid by the Veres One Project to do so. Avoiding a "tragedy of the commons" is essential for sound network economics for a global public utility.

  • Non-speculative - Unlike other ledgers, the Veres One Blockchain has no plans of doing an Initial Coin Offering or a Token Sale. It does not need a speculative network token or cryptocurrency, which eliminates currency speculation, thus ensuring predictable long term operational costs. This approach also frees the network from hundreds of millions of dollars in debt created during an ICO and the rampant speculation that follows.

The Test Network

The Veres One Test Network is in Release Candidate 1 status and is ready for use in Proof of Concepts and Pilot programs.

The network will transition into production after the DID Specification is stabilized at the Rebooting the Web of Trust Spring 2018 event. A map of Veres One Testnet data centers and their connectivity is shown below:

Veres One Testnet Connectivity

Each red place marker is a data center with a 99.999% uptime Service Level Agreement. Red, blue, and green lines represent connectivity to neighboring countries and states. Average global latency to the closest Veres One data center is less than 50ms.

Performance

The Veres One Blockchain uses a leaderless, non-blocking, byzantine fault tolerant consensus algorithm called Continuity. The algorithm reaches consensus with probability 1. There are 3f+1 nodes in the system where f is the number of byzantine failures the network can tolerate. Since the algorithm is non-blocking and nodes can progress at their own pace, the limiting factor is how quickly events can be gossiped around the network. This approach results in very high throughputs. Transactions are limited by two factors:

  1. the fastest 2/3rds of elector's database write speeds and 2) the time it takes to distribute at least 12f + 6 merge events to every elector in the network, the rate of which is an exponential function.

Warning: Benchmarks are not reflective of real world performance

Benchmarking is a poor substitute for measurements taken over long periods of time in hostile environments such as the public Internet. Attacks, routing inefficiencies, packet drops, misconfigured software, and annoying physical limitations such as the speed of light all contribute to degraded performance in real world settings. This section should be taken with a large grain of salt until we have dependable real world data.

Warning: Benchmarks are highly dependent on node configuration

The configuration for the benchmarks used 1 database with 7 electors configured. The database was an AWS AWS i3.large instance consisting of 2 vCPUs, 15.25GB RAM and Local NVME Storage. Each node was an AWS c5.large instance with 2 vCPUs and 4GB RAM.

Based on the goals stated in the previous section, benchmarking has been performed on the reference Veres One implementation that is able to achieve the following performance characteristics.

Metric Capability Description
Throughput 209/sec, 18M/day, 6.6B/year The throughput is a function of how quickly 12f+1 events can be transmitted to each elector. Limiting factors include database write speed, communication speed, and digital signature verification speed.
Consensus Latency ~15-30 seconds The latency is a function of how many electors there are in the system. How many electors there are in the system is a function of the risk tolerance of the network.

The image below shows a testnet operating at a constant rate of 209 operations per second for a 14 hour period. A total of 617,810 events were processed containing roughly 10.5M operations (e.g. DID Documents). Network consensus times averaged around 12 seconds.

Veres One Testnet Performance

The DID Client

A command line did-client exists that enables one to easily create and update DIDs. An example of the client being used to create a Veres One Decentralized Identifier is shown below:

$ ./did create
Executing "create" using ledger "veres"...
Creating new DID on Veres One [test]...
  Generating RSA keypair... (5-15 seconds)
  DID: did:v1:test:nym:AiTSXFbpRt2UbaXSB9YEmc7xtk5f5GdHi2hNNMF3qy4Z
  Storing DID Document on disk...
  DID Document stored in: /home/$USERNAME/...
  Preparing to register DID Document on Veres One...
  Attaching LD-OCAP invocation proof... (~1 second)
  Generating Equihash proof of work... (60-120 seconds)
  Registering DID Document on Veres One...
DID registration successful!

To retrieve the DID Document from any node on the network, run this command:

$ ./did get did:v1:test:nym:AiTSXFbpRt2UbaXSB9YEmc7xtk5f5GdHi2hNNMF3qy4Z
Executing "get" using ledger "veres"...
Retrieving DID Document from Veres One [test]...
{
  "@context": "https://w3id.org/veres-one/v1",
  "id": "did:v1:test:nym:AiTSXFbpRt2UbaXSB9YEmc7xtk5f5GdHi2hNNMF3qy4Z",
  ... rest of DID Document will be displayed here ...

It may take up to 15 seconds for the network to come to consensus, so the retrieval may fail if you try to do it too soon. If it fails, just try again. Once you get a document back, the network guarantees that all nodes on the network will eventually have the document if they do not already have it.

Diving Deeper

The specifics on developing software like the DID Client shown above, including the ability to create, update, and retrieve DID Documents on the Veres One Ledger is detailed in the Veres One DID Method Specification.

Acknowledgements

Thanks to Anil John for his guidance and funding from the United States Department of Homeland Security's Science and Technology Directorate under contract HSHQDC-17-C-00019. The content of this document does not necessarily reflect the position or the policy of the U.S. Government and no official endorsement should be inferred.

Thanks also to the Rebooting the Web of Trust group facilitated by Christopher Allen, Shannon Appelcline, Kiara Robles, Kaliya Young, Brian Weller, Betty Dhamers, and Joe Andrieu. The Internet Identity Workshop community, co-founded by Phil Windley, Kaliya Young, and Doc Searls, also helped shape much of what we've implemented in Veres One. We are also indebted to all of the good people in the W3C Verifiable Credentials WG as well as the W3C Credentials Community Group. The difficult and length debates in each of these comunities has only helped to strengthen Veres One.

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