go/common/crypto/tls: Use ed25519 instead of P-256

This change is breaking as the old certificates are no longer supported,
and they must be regenerated.  Note that this uses the slower runtime
library ed25519 implementation instead of ours due to runtime library
limitations.

.changelog/2058.breaking.md

@@ -0,0 +1,6 @@
+go/common/crypto/tls: Use ed25519 instead of P-256
+
+This change is breaking as the old certificates are no longer supported,
+and they must be regenerated.  Note that this uses the slower runtime
+library ed25519 implementation instead of ours due to runtime library
+limitations.

go/common/crypto/tls/cert.go

@@ -2,8 +2,7 @@
 package tls
 
 import (
-	"crypto/ecdsa"
-	"crypto/elliptic"
+	"crypto/ed25519"
 	"crypto/rand"
 	"crypto/tls"
 	"crypto/x509"
@@ -18,7 +17,7 @@ import (
 )
 
 const (
-	keyPEMType  = "EC PRIVATE KEY"
+	keyPEMType  = "PRIVATE KEY"
 	certPEMType = "CERTIFICATE"
 )
 
@@ -56,7 +55,7 @@ func LoadOrGenerate(certPath, keyPath, commonName string) (*tls.Certificate, err
 
 // Generate generates a new TLS certificate.
 func Generate(commonName string) (*tls.Certificate, error) {
-	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	pubKey, privKey, err := ed25519.GenerateKey(rand.Reader)
 	if err != nil {
 		return nil, errors.Wrap(err, "tls: failed to generate keypair")
 	}
@@ -72,14 +71,14 @@ func Generate(commonName string) (*tls.Certificate, error) {
 	template.NotBefore = time.Now().Add(-1 * time.Hour)
 	template.NotAfter = time.Now().AddDate(1, 0, 0)
 
-	certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, key.Public(), key)
+	certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, pubKey, privKey)
 	if err != nil {
 		return nil, errors.Wrap(err, "tls: failed to create certificate")
 	}
 
 	return &tls.Certificate{
 		Certificate: [][]byte{certDER},
-		PrivateKey:  key,
+		PrivateKey:  privKey,
 	}, nil
 }
 
@@ -93,7 +92,7 @@ func Load(certPath, keyPath string) (*tls.Certificate, error) {
 	if blk == nil || blk.Type != keyPEMType {
 		return nil, errors.New("tls: failed to parse private key PEM")
 	}
-	key, err := x509.ParseECPrivateKey(blk.Bytes)
+	key, err := x509.ParsePKCS8PrivateKey(blk.Bytes)
 	if err != nil {
 		return nil, errors.Wrap(err, "tls: failed to parse private key")
 	}
@@ -125,7 +124,7 @@ func LoadCertificate(certPath string) (*tls.Certificate, error) {
 
 // Save saves a TLS certificate and private key.
 func Save(certPath, keyPath string, cert *tls.Certificate) error {
-	der, err := x509.MarshalECPrivateKey(cert.PrivateKey.(*ecdsa.PrivateKey))
+	der, err := x509.MarshalPKCS8PrivateKey(cert.PrivateKey)
 	if err != nil {
 		return errors.Wrap(err, "tls: failed to serialize private key")
 	}

go/common/identity/identity.go

@@ -2,12 +2,13 @@
 package identity
 
 import (
-	"crypto/ecdsa"
+	"crypto/ed25519"
 	"crypto/rand"
 	"crypto/tls"
 	"path/filepath"
 
 	"github.com/oasislabs/oasis-core/go/common/crypto/signature"
+	"github.com/oasislabs/oasis-core/go/common/crypto/signature/signers/memory"
 	tlsCert "github.com/oasislabs/oasis-core/go/common/crypto/tls"
 )
 
@@ -37,8 +38,8 @@ type Identity struct {
 	P2PSigner signature.Signer
 	// ConsensusSigner is a node consensus key signer.
 	ConsensusSigner signature.Signer
-	// TLSKey is a private key used for TLS connections.
-	TLSKey *ecdsa.PrivateKey
+	// TLSSigner is a node TLS certificate signer.
+	TLSSigner signature.Signer
 	// TLSCertificate is a certificate that can be used for TLS.
 	TLSCertificate *tls.Certificate
 }
@@ -107,7 +108,7 @@ func doLoadOrGenerate(dataDir string, signerFactory signature.SignerFactory, sho
 		NodeSigner:      signers[0],
 		P2PSigner:       signers[1],
 		ConsensusSigner: signers[2],
-		TLSKey:          cert.PrivateKey.(*ecdsa.PrivateKey),
+		TLSSigner:       memory.NewFromRuntime(cert.PrivateKey.(ed25519.PrivateKey)),
 		TLSCertificate:  cert,
 	}, nil
 }

go/common/identity/identity_test.go

@@ -28,7 +28,7 @@ func TestLoadOrGenerate(t *testing.T) {
 	require.EqualValues(t, identity.NodeSigner, identity2.NodeSigner)
 	require.EqualValues(t, identity.P2PSigner, identity2.P2PSigner)
 	require.EqualValues(t, identity.ConsensusSigner, identity2.ConsensusSigner)
-	require.EqualValues(t, identity.TLSKey, identity2.TLSKey)
+	require.EqualValues(t, identity.TLSSigner, identity2.TLSSigner)
 	// TODO: Check that it always generates a fresh certificate once oasis-core#1541 is done.
 	require.EqualValues(t, identity.TLSCertificate, identity2.TLSCertificate)
 }