code: func GenerateKeypair(passphrase string) (*PrivateKey, error) {
  	pub, priv, err := box.GenerateKey(crypto_rand.Reader)
  	if err != nil {
  		return nil, err
  	}
  	k := &PrivateKey{
  		PublicKey: PublicKey{
  			CreationTime: time.Now(),
  			PubKeyAlgo:   PubKeyNaCl,
  			PublicKey:    *pub,
  			Identity:     &xcpb.Identity{},
  		},
  		Encrypted:  true,
  		privateKey: *priv,
  	}
  	err = k.Encrypt(passphrase)
  	return k, err
  }
docs: // GenerateKeypair generates a new keypair