Create the link between root keypair (kbpgp) and CA keypair (node-forge)

[robert-cronin]

As per #94 (comment), there are a few options for doing this:

1. Start with the root keypair and then use a KDF to generate the root x509 certificate pair.
2. Start with the root x509 certificate pair, and then use a KDF to generate the root keypair
3. Use the public-key of the root keypair as the actual public key of the x509 certificate
4. Use the x509 certificate and private key AS the root keypair

[robert-cronin]

within node-forge, we can do something like this to make the x.509 certificate the one and only piece of sharing needed for peer to peer contact. For example the kbpgp public key and peerAddress can be encoded in the public cert via attributes:

const attrs = [
  {
    name: 'commonName',
    value: 'matrixai',
  },
  {
    // kbpgp public key
    type: '1.3.1.4.1',
    value: '<publicKey>'
  },
  {
    // peerAddress
    type: '1.3.1.4.2',
    value: '127.0.0.1:1314'
  }
];
certificate.setSubject(attrs);

where 1.3.1.4.1 and 1.3.1.4.2 are custom OIDs that we can use specifically for encoding polykey specific attributes and this works just fine in node-forge

[robert-cronin]

Closing on account of migration to gitlab