diff --git a/certificate_test.go b/certificate_test.go
index 9951d7a..14b1279 100644
--- a/certificate_test.go
+++ b/certificate_test.go
@@ -16,29 +16,39 @@ var (
 )
 
 func TestCertificateCreation(t *testing.T) {
-	pk, err := NewPrivateKeyEcdsa(elliptic.P224())
+	ed25519Key, err := NewPrivateKeyEd25519()
 	if err != nil {
-		t.Errorf("cert: creating private key failed: %s", err)
+		t.Errorf("cert: creating private key ed25519 failed: %s", err)
 	}
-
-	csr, err := TestCertificateData.ToCertificateRequest(pk)
+	ecdsaKey, err := NewPrivateKeyEcdsa(elliptic.P224())
 	if err != nil {
-		t.Errorf("cert: creating csr failed: %s", err)
+		t.Errorf("cert: creating private key ecdsa failed: %s", err)
 	}
-
-	cert_opts := CertificateOptions{
-		// KeyUsage:  x509.KeyUsageEncipherOnly | x509.KeyUsageKeyEncipherment | x509.KeyUsageCertSign,
-		SerialNumber: big.NewInt(1),
-		CALength:     -1,
-	}
-
-	cert, err := csr.ToCertificate(pk, cert_opts, nil)
+	rsaKey, err := NewPrivateKeyRsa(1024)
 	if err != nil {
-		t.Errorf("cert: creating cert failed: %s", err)
+		t.Errorf("cert: creating private key rsa failed: %s", err)
 	}
 
-	if !fieldsAreSame(TestCertificateData, cert) {
-		t.Errorf("cert: Fields are not the same")
+	for _, pk := range []PrivateKey{rsaKey, ecdsaKey, ed25519Key} {
+		csr, err := TestCertificateData.ToCertificateRequest(pk)
+		if err != nil {
+			t.Errorf("cert: creating csr failed: %s", err)
+		}
+
+		cert_opts := CertificateOptions{
+			// KeyUsage:  x509.KeyUsageEncipherOnly | x509.KeyUsageKeyEncipherment | x509.KeyUsageCertSign,
+			SerialNumber: big.NewInt(1),
+			CALength:     -1,
+		}
+
+		cert, err := csr.ToCertificate(pk, cert_opts, nil)
+		if err != nil {
+			t.Errorf("cert: creating cert failed: %s", err)
+		}
+
+		if !fieldsAreSame(TestCertificateData, cert) {
+			t.Errorf("cert: Fields are not the same")
+		}
 	}
 }
 
diff --git a/ed25519.go b/ed25519.go
index 0104beb..c616e70 100644
--- a/ed25519.go
+++ b/ed25519.go
@@ -45,9 +45,9 @@ func LoadPrivateKeyEd25519(raw []byte) (*Ed25519PrivateKey, error) {
 	return &Ed25519PrivateKey{pr_loaded}, nil
 }
 
-// TODO implement the raw API for the private key
+// PrivateKey returns the private key.
 func (pr *Ed25519PrivateKey) PrivateKey() crypto.PrivateKey {
-	return nil
+	return pr.private_key
 }
 
 // Return the public key for this private key.