Architecture

As already mentioned, Masca is a MetaMask Snap extension. MetaMask Snaps is a system that allows anyone to expand the capabilities of MetaMask safely. This ranges from adding support for other non-EVM blockchains to managing online identity. You can learn more about MetaMask Snaps in this section.

Masca Architecture

Veramo Client

Veramo client powers Masca. Inside Masca, Veramo Client manages DIDs and VCs, using Veramos DIDManager, KeyManager, and PrivateKeyManager plugins and our custom DataManager plugin.

DIDManager, KeyManager, PrivateKeyManager, and DataManager plugins manage and store data. They all come with an abstract data-store class, e.g., AbstractDataStore. Using said class, we implemented custom data-store plugins that save data inside the MetaMask state or on the Ceramic Network.

These abstract classes make implementing different ways of storing data easy.

In the future, users will choose between different DataStore plugins (cloud, other apps, etc.).

Additionally to storing data, Veramo also handles the creation of Verifiable Presentations. ICredentialIssuer is a plugin used to create a VP using one or more VCs with the selected proof format.

If you're interested in how VCs and VPs are generated and how Veramo and its plugins work, visit their documentation!

Error Handling

Masca handles RPC errors internally and returns an object which can either be Success or Error:

export type Result<T> = {
  success: boolean;
} & (
  | {
      success: true;
      data: T;
    }
  | {
      success: false;
      error: string;
    }
);

This can be verified using our utils lib:

import { isError, isSuccess } from '@blockchain-lab-um/utils';

const res = ...

if(isError(res)){
    //RPC method failed
    console.log(res.error)
    ...
}

if(isSuccess(res)){
    //RPC method succeeded
    console.log(res.data)
    ...
}