OpenCerts v1 to v2

OpenCerts v1 to v2 What you need to know

As OpenCerts scales and more institutions use our service, it has been difficult to manage the multitude of pull requests to our github repository. OpenCerts v2.0 resolves that difficulty - no more pull requests and institutions save time by not waiting for pull requests to be approved!

With effect from 31 December 2019, will be shifting to the use of an institute’s own decentralised renderer to render their own certificates. This document will provide information on what you need to know to migrate to OpenCerts v2.


Repository Change

With OpenCerts v2.0, no pull requests for adding/modifying certificates should be made to the original github repository at as the templates have been moved. We will proceed to close all pull request for adding or modifying certificates..

The process for registering your institution with OpenCerts remains the same.

For OpenCerts v1.5 and below, pull requests should be made to the decentralised renderer created for these legacy certificates. The new github repository can be found at

Issuers of OpenCerts are encouraged to upgrade to v2.0 as soon as possible as we will not support adding of new legacy template after 2019.

Cutoff for

Institutes using OpenCerts v1.5 may still add templates or make change to existing templates on legacy templates. However, after 31 December 2019, no pull requests for adding certificates to will be accepted. Instead, institutes will have to create and host their own decentralised renderer to use the OpenCerts platform.


The timeline below illustrates for institutes, the transition from OpenCerts v1.5 to v2.0.

OpenCerts v1 to v2 Timeline

OpenCerts Schema 2.0

What does it (Decentralisation) mean for you?

  1. No more pull requests to

    This means that we will no longer have to approve your pull requests and you will not have to wait for us to merge your pull requests. Now, you can make changes to your codebase without any time lags, improving the speed and efficiency of deploying certificates.

  2. Fault tolerance

    Decentralized renderers are less likely to fail from other institutions’ code errors. This is because each decentralised renderer is reliant on what YOU do, so you can create your certificates with the comfort of knowing that your certificate code is safe from external parties.

  3. Anyone can participate

    Going back to the concept of the web, OpenCerts v2.0 will be a shared network of individually owned decentralisd renderer and the OpenCerts platform, in which everyone participates equally.

    If you want to create a certificate, just host your document renderer, create your own custom certificate, and issue your certificate!

What are the key differences?

OpenCerts v1 to v2 Flow

Schema Change

OpenCerts v1 to v2 Schema Difference

How do I migrate?

We have updated our documentation at to include information on how to transition to OpenCerts v2.0. The image below highlights the difference in steps between OpenCerts v1.5 and v2.0, from creating to issuing your certificate.

OpenCerts v2 Documentation Difference

IMPORTANT Refer to for the documentation on OpenCerts v2.0

OpenCerts 2.0 DNS-TXT Verification

In OpenCerts 2.0 we are further expanding the reach of the OpenCerts ecosystem by allowing the Domain Name System (DNS) to be used as an identity registry - in addition to our current SkillsFuture Singapore Accreditation Registry. A one-liner introduction to the DNS system can be summarised as: “Phonebook for the Internet”. It is indispensible and used by almost all services involving the Internet.

By allowing the DNS system to be used as an identity registry, we let domain name owners claim ownership of an OpenCerts Document Store smart contract on the Ethereum Blockchain.


OpenCerts 1.0 worked on a centralised registry model, governed by SkillsFuture Singapore and administered by GovTech.

Moving to OpenCerts 2.0, we will continue to use this centralised registry model for the institutions that require a higher level of identity assurance. For issuers without this requirement they will be able to simply tie their issuance to their domain name, (e.g The main upgrade is to allow institutes that are able to prove the ownership of a domain to tie the certificate issuer’s identity to the domain name. When a user views a certificate issued under this model, they will see “Certificate issued by”,

How it works

Under IETF RFC 1464, it is possible to store arbitrary string attributes as part of a domain’s record set. This method is currently widely used for email server authentication (SPF, DMARC, DKIM). Our DNS identity proof technique was largely inspired by Keybase DNS proofs.

Only domain name owners (and the registrar that they trust) have the authority to make changes to the records associated with that domain name. Thus when a DNS record endorses a certain fact, it transitively asserts that this fact is believed to be true by the domain name owner.

In an OpenCerts 2.0 DNS-TXT identity proof, we record an OpenCerts Document Store address and the network (e.g Ethereum, Main Net) it is on. In the OpenCert document itself, we declare the domain name to search for the record as well as the Document Store Ethereum address. This forms a bi-directional trust assertion, and if the OpenCert’s cryptographic proof is issued on that Document Store - we can say that the domain name owner has endorsed the issuance of this OpenCert document.


A deeper technical discussion of this topic can be found at OpenCerts 2.0 DNS-TXT Architecture Decision Record

Actions to Implement

  1. Create DNS TXT Record

    The issuer will need to add a DNS TXT record to his domain name, the exact steps to achieve this can be confirmed with their domain name registrar.

    The TXT record should look like

    openatts net=ethereum netId=1 addr=0x9178F546D3FF57D7A6352bD61B80cCCD46199C2d

    Optionally, the issuer may also publish an A record at the same address so that the if the certificate viewer clicks on the URL, they can see some helpful text regarding the issuer’s OpenCerts program.

  2. Certificate Schema Changes

    In addition to Decentralised Rendering which will also require schema changes in OpenCerts 2.0, DNS verification adds a field identityProof to the issuer object. The issuer will need to already have deployed a Document Store contract as well as created the DNS TXT record as above.

    The identityProof object will look like:

    "issuers": [
        "network": "ETHEREUM",
        "documentStore": "0x9178F546D3FF57D7A6352bD61B80cCCD46199C2d",
        "identityProof": {
            "type": "DNS-TXT",
            "location": ""


To sum up, OpenCerts 2.0 is going to be awesome! For independent issuers, you may now prove your identity with DNS and style your certificate look-and-feel. For registered institutes, you may now style your certificates wthout being bottlenecked by the core developers.

If you have any concerns or questions, please hit us up on our Github Issuer Tracker as always :)