![EBSI Logo](https://ec.europa.eu/digital-building-blocks/sites/images/logo/default-space-logo.svg)

# EBSI NP DID Resolver

This library supports the [`did:key` method](https://w3c-ccg.github.io/did-method-key/):

```
did-key-format := did:key:MULTIBASE(base58-btc, MULTICODEC(public-key-type, raw-public-key-bytes))
```

Note: the library only supports the `jwk_jcs-pub` public key type (code: `0xeb51`). It corresponds to a JWK with [required members only](https://www.rfc-editor.org/rfc/rfc7638.html#section-3.2) through [JCS](https://www.rfc-editor.org/rfc/rfc8785).

It requires the [`did-resolver`](https://github.com/decentralized-identity/did-resolver) library, which is the primary interface for resolving DIDs.

## Table of Contents

1. [Installation](#installation)
2. [Resolving a DID document](#resolving-a-did-document)
3. [Creating a DID from a JWK](#creating-a-did-from-a-jwk)
4. [Validating a DID](#validating-a-did)
5. [License](#license)

## Installation

```bash
npm install @cef-ebsi/key-did-resolver
```

or if you use `yarn`:

```bash
yarn add @cef-ebsi/key-did-resolver
```

## Resolving a DID document

The library provides a resolver that is meant to be used through the [`did-resolver`](https://github.com/decentralized-identity/did-resolver) aggregator.

```js
import { Resolver } from "did-resolver";
import { getResolver } from "@cef-ebsi/key-did-resolver";

// getResolver will return an object with a key/value pair of { "key": resolver } where resolver is a function used by the generic DID resolver.
const keyResolver = getResolver();
const didResolver = new Resolver(keyResolver);

didResolver
  .resolve(
    "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r",
  )
  .then((doc) => console.log(doc));

// You can also use ES7 async/await syntax
const doc = await didResolver.resolve(
  "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r",
);
console.log(doc);

/* 
Prints:

{
  "didDocument": {
    "@context": [
      "https://www.w3.org/ns/did/v1",
      "https://w3id.org/security/suites/jws-2020/v1"
    ],
    "id": "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r",
    "verificationMethod": [
      {
        "id": "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r#z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r",
        "type": "JsonWebKey2020",
        "controller": "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r",
        "publicKeyJwk": {
          "crv": "P-256",
          "kty": "EC",
          "x": "ngy44T1vxAT6Di4nr-UaM9K3Tlnz9pkoksDokKFkmNc",
          "y": "QCRfOKlSM31GTkb4JHx3nXB4G_jSPMsbdjzlkT_UpPc"
        }
      }
    ],
    "authentication": [
      "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r#z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r"
    ],
    "assertionMethod": [
      "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r#z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r"
    ],
    "capabilityInvocation": [
      "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r#z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r"
    ],
    "capabilityDelegation": [
      "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r#z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r"
    ]
  },
  "didDocumentMetadata": {},
  "didResolutionMetadata": {
    "contentType": "application/did+ld+json"
  }
}
*/
```

## Creating a DID from a JWK

The library exposes a method allowing you to create a DID from a JWK:

```js
import { util } from "@cef-ebsi/key-did-resolver";

const jwk = {
  kty: "EC",
  crv: "P-256",
  x: "ngy44T1vxAT6Di4nr-UaM9K3Tlnz9pkoksDokKFkmNc",
  y: "QCRfOKlSM31GTkb4JHx3nXB4G_jSPMsbdjzlkT_UpPc",
};

const did = util.createDid(jwk);

// did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r
```

## Validating a DID

The library also exposes a method to assert if a DID is valid:

```js
import { util } from "@cef-ebsi/key-did-resolver";

const did =
  "did:key:z2dmzD81cgPx8Vki7JbuuMmFYrWPgYoytykUZ3eyqht1j9KbsEYvdrjxMjQ4tpnje9BDBTzuNDP3knn6qLZErzd4bJ5go2CChoPjd5GAH3zpFJP5fuwSk66U5Pq6EhF4nKnHzDnznEP8fX99nZGgwbAh1o7Gj1X52Tdhf7U4KTk66xsA5r";

util.validateDid(did); // Will throw an error if the DID is not valid
```

## License

Copyright (C) 2025 European Union

This program is free software: you can redistribute it and/or modify it under the terms of the EUROPEAN UNION PUBLIC LICENCE v. 1.2 as published by the European Union.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the EUROPEAN UNION PUBLIC LICENCE v. 1.2 for further details.

You should have received a copy of the EUROPEAN UNION PUBLIC LICENCE v. 1.2. along with this program. If not, see <https://joinup.ec.europa.eu/collection/eupl/eupl-text-eupl-12>.