Improve docs around creating peerId from private key and improve support

[jacobheun]

Doc Updates

The docs for createFromPrivKey currently reads:

createFromPrivKey(privKey)

• privKey: Buffer
  Creates a Peer ID from a buffer containing a private key.

This is missleading as it requires a ProtoBuf.

We should clarify the documentation for this as users may try to use simple Buffer.

Improved Support

It would be nice if we improved the support for creating a peerid from a private key to accept a simple buffer. This could allow users to generate a keypair and use that privatekey to create their peerid. A use case of this might be an EC2 instance where the private key is stored in AWS KMS. It's possible to do this leveraging libp2p-crypto, but it would be nice if a factory method existed in peer-id to handle this for users.

[daviddias]

Treat documentation mistakes as bugs. That said, proposal sounds good :)

[iamsaquib8]

And Please can you provide examples to start with in the docs, its tough to find out the starting point for many of the methods defined in the library. Thanks

[vogdb]

Hi! Is this still actual?

cc @vasco-santos

[wemeetagain]

Yes, createFromPrivKey still expects a protobuf

eg:

import { keys } from "libp2p-crypto"

const privateKey = await keys.generateKeypair('secp256k1')

// this doesn't work
const peerId = await createFromPrivKey(privateKey.marshal())

// this works
const peerId = await createFromPrivKey(privateKey.bytes)

[vogdb]

@wemeetagain can you please elaborate on your example? I see that everything works in the tests https://github.com/libp2p/js-peer-id/blob/master/test/peer-id.spec.js#L214. From what I see the API has changed:

const privKey = await crypto.keys.generateKeyPair('secp256k1', 256)
const id = await PeerId.createFromPrivKey(privKey.bytes)

[wemeetagain]

Ah, sorry, there are a bunch of bugs in my example. (I just updated it)

privKey.bytes returns a protobuf-wrapped private key. https://github.com/libp2p/js-libp2p-crypto/blob/master/src/keys/secp256k1-class.ts#L66
whereas privKey.marshal() returns the raw private key https://github.com/libp2p/js-libp2p-crypto/blob/master/src/keys/secp256k1-class.ts#L62

[vogdb]

@wemeetagain As a beginner I can create a PR that updates documentation. Please look at the branch of my fork https://github.com/libp2p/js-peer-id/compare/master...vogdb:readme-privkey?expand=1. If it is ok then I will create it.

If you want to change API to accept createFromPrivKey(privateKey.marshal()) then it would be better to discuss such change with the project's maintainers first.