Ed25519VerificationKey2020 Key Pair Library for Linked Data (@digitalcredentials/ed25519-verification-key-2020)

Typescript/Javascript library for generating and working with Ed25519VerificationKey2020 key pairs, for use with crypto-ld.

Table of Contents

• Background
• Security
• Install
• Usage
• Contribute
• Commercial Support
• License

Background

(Forked from digitalbazaar/ed25519-verification-key-2020 v4.1.0 to provide TypeScript compatibility.)

For use with:

• @digitalcredentials/ed25519-signature-2020 ^2.0.0 crypto suite (with linked-data-integrity)
• @digitalcredentials/vc ^2.0.0

See also (related specs):

• Ed25519VerificationKey2020 spec.

Security

As with most security- and cryptography-related tools, the overall security of your system will largely depend on your design decisions.

Install

• Node.js 16+ is required.

To install locally (for development):

git clone https://github.com/digitalcredentials/ed25519-verification-key-2020.git
cd ed25519-verification-key-2020
npm install

Usage

Generating a new public/private key pair

To generate a new public/private key pair:

• {string} [controller] Optional controller URI or DID to initialize the generated key. (This will also init the key id.)
• {string} [seed] Optional deterministic seed value from which to generate the key.

import {Ed25519VerificationKey2020} from '@digitalcredentials/ed25519-verification-key-2020';

const edKeyPair = await Ed25519VerificationKey2020.generate();

Importing a key pair from storage

To create an instance of a public/private key pair from data imported from storage, use .from():

const serializedKeyPair = { ... };

const keyPair = await Ed25519VerificationKey2020.from(serializedKeyPair);

Exporting the public key only

To export just the public key of a pair:

await keyPair.export({publicKey: true});
// ->
{ 
  type: 'Ed25519VerificationKey2020',
  id: 'did:example:1234#z6MkszZtxCmA2Ce4vUV132PCuLQmwnaDD5mw2L23fGNnsiX3',
  controller: 'did:example:1234',
  publicKeyMultibase: 'zEYJrMxWigf9boyeJMTRN4Ern8DJMoCXaLK77pzQmxVjf'
}

Exporting the full public-private key pair

To export the full key pair, including private key (warning: this should be a carefully considered operation, best left to dedicated Key Management Systems):

await keyPair.export({publicKey: true, privateKey: true});
// ->
{
  type: 'Ed25519VerificationKey2020',
  id: 'did:example:1234#z6MkszZtxCmA2Ce4vUV132PCuLQmwnaDD5mw2L23fGNnsiX3',
  controller: 'did:example:1234',
  publicKeyMultibase: 'zEYJrMxWigf9boyeJMTRN4Ern8DJMoCXaLK77pzQmxVjf',
  privateKeyMultibase: 'z4E7Q4neNHwv3pXUNzUjzc6TTYspqn9Aw6vakpRKpbVrCzwKWD4hQDHnxuhfrTaMjnR8BTp9NeUvJiwJoSUM6xHAZ'
}

Generating and verifying key fingerprint

To generate a fingerprint:

keyPair.fingerprint();
// ->
'z6MkszZtxCmA2Ce4vUV132PCuLQmwnaDD5mw2L23fGNnsiX3'

To verify a fingerprint:

const fingerprint = 'z6MkszZtxCmA2Ce4vUV132PCuLQmwnaDD5mw2L23fGNnsiX3';
keyPair.verifyFingerprint({fingerprint});
// ->
{verified: true}

Creating a signer function

In order to perform a cryptographic signature, you need to create a sign function, and then invoke it.

const keyPair = Ed25519VerificationKey2020.generate();

const {sign} = keyPair.signer();

// data is a Uint8Array of bytes
const data = (new TextEncoder()).encode('test data goes here');
// Signing also outputs a Uint8Array, which you can serialize to text etc.
const signatureValueBytes = await sign({data});

Creating a verifier function

In order to verify a cryptographic signature, you need to create a verify function, and then invoke it (passing it the data to verify, and the signature).

const keyPair = Ed25519VerificationKey2020.generate();

const {verify} = keyPair.verifier();

const verified = await verify({data, signature});
// true

Converting to and from previous Ed25519VerificationKey2018 key type

If you have serialized and stored keys of the previous Ed25519VerificationKey2018 key type (for example, generated using the ed25519-verification-key-2018) library, or using the Ed25519KeyPair keys bundled with crypto-ld v3.x), things to keep in mind:

• Instances of those key types still contain the same key material, the only thing that has changed from the 2018 suite to the 2020 suite is the way the public and private key material is serialized when exporting. The 2018 suite key types serialize using the publicKeyBase58 and privateKeyBase58 properties, and the 2020 suite key (this repo) serializes using corresponding publicKeyMultibase and privateKeyMultibase property.
• You can convert from the 2018 key type to the 2020 key type using the provided Ed25519VerificationKey2020.fromEd25519VerificationKey2018() method (see below).
• They generate() the same key material, given the same seed parameter.
• Both the 2018 and 2020 keys produce and verify the same signatures.

Example of converting from 2018:

import {Ed25519VerificationKey2018}
  from '@digitalbazaar/ed25519-verification-key-2018';
import {Ed25519VerificationKey2020}
  from '@digitalbazaar/ed25519-verification-key-2020';

const keyPair2018 = await Ed25519VerificationKey2018.generate({
  controller: 'did:example:1234'
});

const keyPair2020 = await Ed25519VerificationKey2020
  .fromEd25519VerificationKey2018({keyPair: keyPair2018});

// The resulting keyPair2020 will have the same `id` and `controller` properties
// as its 2018 source. They will also produce and verify the same signatures.

// data is a Uint8Array of bytes
const data = (new TextEncoder()).encode('test data goes here');
const signatureBytes2018 = await keyPair2018.signer().sign({data});

// this is the same signature as that produced by the 2020 key. And will verify
// the same.
await keyPair2020.verifier().verify({data, signature: signatureBytes2018})
// true

Example of converting to the 2018 serialization:

const keyPair2020 = await Ed25519VerificationKey2020.generate({
  controller: 'did:example:1234'
});

const keyObject2018 = keyPair2020.toEd255519VerificationKey2018({
  publicKey: true, privateKey: true, includeContext: true
});

Contribute

PRs accepted.

If editing the Readme, please conform to the standard-readme specification.

License

• MIT License - DCC - TypeScript compatibility.
• New BSD License (3-clause) © 2020-2021 Digital Bazaar - Initial implementation.