Set public key from private key in DNSKEY instead of copying it from …

…DNSKEY to private key

Previously when loading a PrivateKey into a DNSKEY we would return the PrivateKey with the PublicKey set from the DNSKEY struct.
Now that behaviour is flipped and the PublicKey is taken from the PrivateKey and set in the DNSKEY.

dnssec_keyscan.go

@@ -5,6 +5,7 @@ import (
 	"crypto"
 	"crypto/ecdsa"
 	"crypto/ed25519"
+	"crypto/elliptic"
 	"crypto/rsa"
 	"io"
 	"math/big"
@@ -48,22 +49,21 @@ func (k *DNSKEY) ReadPrivateKey(q io.Reader, file string) (crypto.PrivateKey, er
 		if err != nil {
 			return nil, err
 		}
-		pub := k.publicKeyRSA()
-		if pub == nil {
-			return nil, ErrKey
-		}
-		priv.PublicKey = *pub
+		k.setPublicKeyRSA(priv.PublicKey.E, priv.PublicKey.N)
 		return priv, nil
 	case ECDSAP256SHA256, ECDSAP384SHA384:
 		priv, err := readPrivateKeyECDSA(m)
 		if err != nil {
 			return nil, err
 		}
-		pub := k.publicKeyECDSA()
-		if pub == nil {
-			return nil, ErrKey
+		switch uint8(algo) {
+		case ECDSAP256SHA256:
+			priv.PublicKey.Curve = elliptic.P256()
+		case ECDSAP384SHA384:
+			priv.PublicKey.Curve = elliptic.P384()
 		}
-		priv.PublicKey = *pub
+		priv.PublicKey.X, priv.PublicKey.Y = priv.PublicKey.Curve.ScalarBaseMult(priv.D.Bytes())
+		k.setPublicKeyECDSA(priv.PublicKey.X, priv.PublicKey.Y)
 		return priv, nil
 	case ED25519:
 		return readPrivateKeyED25519(m)