Switch from govendor to go modules. (#587)

Thanks to @BenoitKnecht for leading the way on this.

vendor/github.com/miekg/dns/dnssec_keygen.go

@@ -8,6 +8,8 @@ import (
 	"crypto/rand"
 	"crypto/rsa"
 	"math/big"
+
+	"golang.org/x/crypto/ed25519"
 )
 
 // Generate generates a DNSKEY of the given bit size.
@@ -38,6 +40,10 @@ func (k *DNSKEY) Generate(bits int) (crypto.PrivateKey, error) {
 		if bits != 384 {
 			return nil, ErrKeySize
 		}
+	case ED25519:
+		if bits != 256 {
+			return nil, ErrKeySize
+		}
 	}
 
 	switch k.Algorithm {
@@ -75,6 +81,13 @@ func (k *DNSKEY) Generate(bits int) (crypto.PrivateKey, error) {
 		}
 		k.setPublicKeyECDSA(priv.PublicKey.X, priv.PublicKey.Y)
 		return priv, nil
+	case ED25519:
+		pub, priv, err := ed25519.GenerateKey(rand.Reader)
+		if err != nil {
+			return nil, err
+		}
+		k.setPublicKeyED25519(pub)
+		return priv, nil
 	default:
 		return nil, ErrAlg
 	}
@@ -117,6 +130,15 @@ func (k *DNSKEY) setPublicKeyDSA(_Q, _P, _G, _Y *big.Int) bool {
 	return true
 }
 
+// Set the public key for Ed25519
+func (k *DNSKEY) setPublicKeyED25519(_K ed25519.PublicKey) bool {
+	if _K == nil {
+		return false
+	}
+	k.PublicKey = toBase64(_K)
+	return true
+}
+
 // Set the public key (the values E and N) for RSA
 // RFC 3110: Section 2. RSA Public KEY Resource Records
 func exponentToBuf(_E int) []byte {