Add Public() method

protocol/meshcore/crypto/ed25519.go

@@ -2,6 +2,7 @@ package crypto
 
 import (
 	"bytes"
+	"crypto"
 	"crypto/rand"
 	"crypto/sha512"
 	"encoding/base64"
@@ -45,6 +46,12 @@ func (priv *PrivateKey) Seed() []byte {
 	return seed[:]
 }
 
+func (priv *PrivateKey) Public() crypto.PublicKey {
+	p := &PublicKey{}
+	newPublicKey(p, priv.pub[:])
+	return p
+}
+
 func (priv *PrivateKey) PublicKey() []byte {
 	pub := priv.pub
 	return pub[:]
@@ -412,3 +419,5 @@ func verifyWithDom(pub *PublicKey, message, sig []byte, domPrefix, context strin
 	}
 	return nil
 }
+
+var _ crypto.PrivateKey = (*PrivateKey)(nil)