Set SKI, support multi hosts, add Signer to CA

Signed-off-by: Matthew Sykes <sykesmat@us.ibm.com>

common/crypto/tlsgen/ca.go

@@ -40,7 +40,10 @@ type CA interface {
 	// with a given custom SAN.
 	// The certificate is signed by the CA.
 	// Returns nil, error in case of failure
-	NewServerCertKeyPair(host string) (*CertKeyPair, error)
+	NewServerCertKeyPair(hosts ...string) (*CertKeyPair, error)
+
+	// Signer returns a crypto.Signer that signs with the CA's private key.
+	Signer() crypto.Signer
 }
 
 type ca struct {
@@ -50,7 +53,7 @@ type ca struct {
 func NewCA() (CA, error) {
 	c := &ca{}
 	var err error
-	c.caCert, err = newCertKeyPair(true, false, "", nil, nil)
+	c.caCert, err = newCertKeyPair(true, false, nil, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -60,7 +63,7 @@ func NewCA() (CA, error) {
 func (c *ca) NewIntermediateCA() (CA, error) {
 	intermediateCA := &ca{}
 	var err error
-	intermediateCA.caCert, err = newCertKeyPair(true, false, "", c.caCert.Signer, c.caCert.TLSCert)
+	intermediateCA.caCert, err = newCertKeyPair(true, false, c.caCert.Signer, c.caCert.TLSCert)
 	if err != nil {
 		return nil, err
 	}
@@ -76,16 +79,21 @@ func (c *ca) CertBytes() []byte {
 // or nil, error in case of failure
 // The certificate is signed by the CA and is used as a client TLS certificate
 func (c *ca) NewClientCertKeyPair() (*CertKeyPair, error) {
-	return newCertKeyPair(false, false, "", c.caCert.Signer, c.caCert.TLSCert)
+	return newCertKeyPair(false, false, c.caCert.Signer, c.caCert.TLSCert)
 }
 
 // newServerCertKeyPair returns a certificate and private key pair and nil,
 // or nil, error in case of failure
 // The certificate is signed by the CA and is used as a server TLS certificate
-func (c *ca) NewServerCertKeyPair(host string) (*CertKeyPair, error) {
-	keypair, err := newCertKeyPair(false, true, host, c.caCert.Signer, c.caCert.TLSCert)
+func (c *ca) NewServerCertKeyPair(hosts ...string) (*CertKeyPair, error) {
+	keypair, err := newCertKeyPair(false, true, c.caCert.Signer, c.caCert.TLSCert, hosts...)
 	if err != nil {
 		return nil, err
 	}
 	return keypair, nil
 }
+
+// Signer returns a crypto.Signer that signs with the CA's private key.
+func (c *ca) Signer() crypto.Signer {
+	return c.caCert.Signer
+}

common/crypto/tlsgen/ca_test.go

@@ -82,3 +82,9 @@ func TestTLSCA(t *testing.T) {
 	assert.Error(t, err)
 	assert.Contains(t, err.Error(), "context deadline exceeded")
 }
+
+func TestTLSCASigner(t *testing.T) {
+	tlsCA, err := NewCA()
+	assert.NoError(t, err)
+	assert.Equal(t, tlsCA.(*ca).caCert.Signer, tlsCA.Signer())
+}

common/crypto/tlsgen/key.go

@@ -11,6 +11,7 @@ import (
 	"crypto/ecdsa"
 	"crypto/elliptic"
 	"crypto/rand"
+	"crypto/sha256"
 	"crypto/x509"
 	"crypto/x509/pkix"
 	"encoding/pem"
@@ -47,7 +48,7 @@ func newCertTemplate() (x509.Certificate, error) {
 	}, nil
 }
 
-func newCertKeyPair(isCA bool, isServer bool, host string, certSigner crypto.Signer, parent *x509.Certificate) (*CertKeyPair, error) {
+func newCertKeyPair(isCA bool, isServer bool, certSigner crypto.Signer, parent *x509.Certificate, hosts ...string) (*CertKeyPair, error) {
 	privateKey, privBytes, err := newPrivKey()
 	if err != nil {
 		return nil, err
@@ -74,12 +75,15 @@ func newCertKeyPair(isCA bool, isServer bool, host string, certSigner crypto.Sig
 	if isServer {
 		template.NotAfter = tenYearsFromNow
 		template.ExtKeyUsage = append(template.ExtKeyUsage, x509.ExtKeyUsageServerAuth)
-		if ip := net.ParseIP(host); ip != nil {
-			template.IPAddresses = append(template.IPAddresses, ip)
-		} else {
-			template.DNSNames = append(template.DNSNames, host)
+		for _, host := range hosts {
+			if ip := net.ParseIP(host); ip != nil {
+				template.IPAddresses = append(template.IPAddresses, ip)
+			} else {
+				template.DNSNames = append(template.DNSNames, host)
+			}
 		}
 	}
+	template.SubjectKeyId = computeSKI(&privateKey.PublicKey)
 	// If no parent cert, it's a self signed cert
 	if parent == nil || certSigner == nil {
 		parent = &template
@@ -111,3 +115,10 @@ func newCertKeyPair(isCA bool, isServer bool, host string, certSigner crypto.Sig
 func encodePEM(keyType string, data []byte) []byte {
 	return pem.EncodeToMemory(&pem.Block{Type: keyType, Bytes: data})
 }
+
+// RFC 7093, Section 2, Method 4
+func computeSKI(key *ecdsa.PublicKey) []byte {
+	raw := elliptic.Marshal(key.Curve, key.X, key.Y)
+	hash := sha256.Sum256(raw)
+	return hash[:]
+}

common/crypto/tlsgen/key_test.go

@@ -16,7 +16,7 @@ import (
 )
 
 func TestLoadCert(t *testing.T) {
-	pair, err := newCertKeyPair(false, false, "", nil, nil)
+	pair, err := newCertKeyPair(false, false, nil, nil)
 	assert.NoError(t, err)
 	assert.NotNil(t, pair)
 	tlsCertPair, err := tls.X509KeyPair(pair.Cert, pair.Key)

internal/cryptogen/ca/ca.go

@@ -167,7 +167,7 @@ func (ca *CA) SignCertificate(
 	return cert, nil
 }
 
-// compute Subject Key Identifier
+// compute Subject Key Identifier using RFC 7093, Section 2, Method 4
 func computeSKI(privKey *ecdsa.PrivateKey) []byte {
 	// Marshall the public key
 	raw := elliptic.Marshal(privKey.Curve, privKey.PublicKey.X, privKey.PublicKey.Y)