sidh: adds PQ secure KEX

* SIDH/P503-X25519
* adds interop tests

13.go

@@ -21,6 +21,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	sidh "github_com/cloudflare/sidh/sidh"
 	"golang_org/x/crypto/curve25519"
 )
 
@@ -29,11 +30,16 @@ import (
 const numSessionTickets = 2
 
 type secretLabel int
-type role uint8
 
 const (
-	kRole_Server = iota
+	x25519SharedSecretSz = 32
-	kRole_Client
+
+	P503PubKeySz                  = 378
+	P503PrvKeySz                  = 32
+	P503SharedSecretSz            = 126
+	SidhP503Curve25519PubKeySz    = x25519SharedSecretSz + P503PubKeySz
+	SidhP503Curve25519PrvKeySz    = x25519SharedSecretSz + P503PrvKeySz
+	SidhP503Curve25519SharedKeySz = x25519SharedSecretSz + P503SharedSecretSz
 )
 
 const (
@@ -55,6 +61,38 @@ type keySchedule13 struct {
 	config         *Config   // Used for KeyLogWriter callback, nil if keylogging is disabled.
 }
 
+// Interface implemented by DH key exchange strategies
+type dhKex interface {
+	// c - context of current TLS handshake, groupId - ID of an algorithm
+	// (curve/field) being chosen for key agreement. Methods implmenting an
+	// interface always assume that provided groupId is correct.
+	//
+	// In case of success, function returns secret key and ephemeral key. Otherwise
+	// error is set.
+	generate(c *Conn, groupId CurveID) ([]byte, keyShare, error)
+	// c - context of current TLS handshake, ks - public key received
+	// from the other side of the connection, secretKey - is a private key
+	// used for DH key agreement. Function returns shared secret in case
+	// of success or empty slice otherwise.
+	derive(c *Conn, ks keyShare, secretKey []byte) []byte
+}
+
+// Key Exchange strategies per curve type
+type kexNist struct{}                 // Used by NIST curves; P-256, P-384, P-512
+type kexX25519 struct{}               // Used by X25519
+type kexSidhP503 struct{}             // Used by SIDH/P503
+type kexHybridSidhP503X25519 struct{} // Used by SIDH-ECDH hybrid scheme
+
+// Routing map for key exchange strategies
+var dhKexStrat = map[CurveID]dhKex{
+	CurveP256:                &kexNist{},
+	CurveP384:                &kexNist{},
+	CurveP521:                &kexNist{},
+	X25519:                   &kexX25519{},
+	sidhP503:                 &kexSidhP503{},
+	HybridSidhP503Curve25519: &kexHybridSidhP503X25519{},
+}
+
 func newKeySchedule13(suite *cipherSuite, config *Config, clientRandom []byte) *keySchedule13 {
 	if config.KeyLogWriter == nil {
 		clientRandom = nil
@@ -80,6 +118,15 @@ func (ks *keySchedule13) setSecret(secret []byte) {
 	ks.secret = hkdfExtract(hash, secret, salt)
 }
 
+// Depending on role returns pair of key variant to be used by
+// local and remote process.
+func getSidhKeyVariant(isClient bool) (sidh.KeyVariant, sidh.KeyVariant) {
+	if isClient {
+		return sidh.KeyVariant_SIDH_A, sidh.KeyVariant_SIDH_B
+	}
+	return sidh.KeyVariant_SIDH_B, sidh.KeyVariant_SIDH_A
+}
+
 // write appends the data to the transcript hash context.
 func (ks *keySchedule13) write(data []byte) {
 	ks.handshakeCtx = nil
@@ -186,7 +233,7 @@ CurvePreferenceLoop:
 
 	earlyClientCipher, _ := hs.keySchedule.prepareCipher(secretEarlyClient)
 
-	ecdheSecret := c.deriveECDHESecret(ks, privateKey)
+	ecdheSecret := c.deriveDHESecret(ks, privateKey)
 	if ecdheSecret == nil {
 		c.sendAlert(alertIllegalParameter)
 		return errors.New("tls: bad ECDHE client share")
@@ -551,61 +598,22 @@ func prepareDigitallySigned(hash crypto.Hash, context string, data []byte) []byt
 	return h.Sum(nil)
 }
 
+// generateKeyShare generates keypair. Private key is returned as first argument, public key
+// is returned in keyShare.data. keyshare.curveID stores ID of the scheme used.
 func (c *Conn) generateKeyShare(curveID CurveID) ([]byte, keyShare, error) {
-	if curveID == X25519 {
+	if val, ok := dhKexStrat[curveID]; ok {
-		var scalar, public [32]byte
+		return val.generate(c, curveID)
-		if _, err := io.ReadFull(c.config.rand(), scalar[:]); err != nil {
-			return nil, keyShare{}, err
-		}
-
-		curve25519.ScalarBaseMult(&public, &scalar)
-		return scalar[:], keyShare{group: curveID, data: public[:]}, nil
 	}
-
+	return nil, keyShare{}, errors.New("tls: preferredCurves includes unsupported curve")
-	curve, ok := curveForCurveID(curveID)
-	if !ok {
-		return nil, keyShare{}, errors.New("tls: preferredCurves includes unsupported curve")
-	}
-
-	privateKey, x, y, err := elliptic.GenerateKey(curve, c.config.rand())
-	if err != nil {
-		return nil, keyShare{}, err
-	}
-	ecdhePublic := elliptic.Marshal(curve, x, y)
-
-	return privateKey, keyShare{group: curveID, data: ecdhePublic}, nil
 }
 
-func (c *Conn) deriveECDHESecret(ks keyShare, secretKey []byte) []byte {
+// DH key agreement. ks stores public key, secretKey stores private key used for ephemeral
-	if ks.group == X25519 {
+// key agreement. Function returns shared secret in case of success or empty slice otherwise.
-		if len(ks.data) != 32 {
+func (c *Conn) deriveDHESecret(ks keyShare, secretKey []byte) []byte {
-			return nil
+	if val, ok := dhKexStrat[ks.group]; ok {
-		}
+		return val.derive(c, ks, secretKey)
-
-		var theirPublic, sharedKey, scalar [32]byte
-		copy(theirPublic[:], ks.data)
-		copy(scalar[:], secretKey)
-		curve25519.ScalarMult(&sharedKey, &scalar, &theirPublic)
-		return sharedKey[:]
 	}
-
+	return nil
-	curve, ok := curveForCurveID(ks.group)
-	if !ok {
-		return nil
-	}
-	x, y := elliptic.Unmarshal(curve, ks.data)
-	if x == nil {
-		return nil
-	}
-	x, _ = curve.ScalarMult(x, y, secretKey)
-	xBytes := x.Bytes()
-	curveSize := (curve.Params().BitSize + 8 - 1) >> 3
-	if len(xBytes) == curveSize {
-		return xBytes
-	}
-	buf := make([]byte, curveSize)
-	copy(buf[len(buf)-len(xBytes):], xBytes)
-	return buf
 }
 
 func hkdfExpandLabel(hash crypto.Hash, secret, hashValue []byte, label string, L int) []byte {
@@ -981,7 +989,7 @@ func (hs *clientHandshakeState) doTLS13Handshake() error {
 
 	// 0-RTT is not supported yet, so use an empty PSK.
 	hs.keySchedule.setSecret(nil)
-	ecdheSecret := c.deriveECDHESecret(serverHello.keyShare, hs.privateKey)
+	ecdheSecret := c.deriveDHESecret(serverHello.keyShare, hs.privateKey)
 	if ecdheSecret == nil {
 		c.sendAlert(alertIllegalParameter)
 		return errors.New("tls: bad ECDHE server share")
@@ -1161,3 +1169,138 @@ func supportedSigAlgorithmsCert(schemes []SignatureScheme) (ret []SignatureSchem
 	}
 	return
 }
+
+// Functions below implement dhKex interface for different DH shared secret agreements
+
+// KEX: P-256, P-384, P-512 KEX
+func (kexNist) generate(c *Conn, groupId CurveID) (private []byte, ks keyShare, err error) {
+	// never fails
+	curve, _ := curveForCurveID(groupId)
+	private, x, y, err := elliptic.GenerateKey(curve, c.config.rand())
+	if err != nil {
+		return nil, keyShare{}, err
+	}
+	ks.group = groupId
+	ks.data = elliptic.Marshal(curve, x, y)
+	return
+}
+func (kexNist) derive(c *Conn, ks keyShare, secretKey []byte) []byte {
+	// never fails
+	curve, _ := curveForCurveID(ks.group)
+	x, y := elliptic.Unmarshal(curve, ks.data)
+	if x == nil {
+		return nil
+	}
+	x, _ = curve.ScalarMult(x, y, secretKey)
+	xBytes := x.Bytes()
+	curveSize := (curve.Params().BitSize + 8 - 1) >> 3
+	if len(xBytes) == curveSize {
+		return xBytes
+	}
+	buf := make([]byte, curveSize)
+	copy(buf[len(buf)-len(xBytes):], xBytes)
+	return buf
+}
+
+// KEX: X25519
+func (kexX25519) generate(c *Conn, groupId CurveID) ([]byte, keyShare, error) {
+	var scalar, public [x25519SharedSecretSz]byte
+	if _, err := io.ReadFull(c.config.rand(), scalar[:]); err != nil {
+		return nil, keyShare{}, err
+	}
+	curve25519.ScalarBaseMult(&public, &scalar)
+	return scalar[:], keyShare{group: X25519, data: public[:]}, nil
+}
+
+func (kexX25519) derive(c *Conn, ks keyShare, secretKey []byte) []byte {
+	var theirPublic, sharedKey, scalar [x25519SharedSecretSz]byte
+	if len(ks.data) != x25519SharedSecretSz {
+		return nil
+	}
+	copy(theirPublic[:], ks.data)
+	copy(scalar[:], secretKey)
+	curve25519.ScalarMult(&sharedKey, &scalar, &theirPublic)
+	return sharedKey[:]
+}
+
+// KEX: SIDH/503
+func (kexSidhP503) generate(c *Conn, groupId CurveID) ([]byte, keyShare, error) {
+	var variant, _ = getSidhKeyVariant(c.isClient)
+	var prvKey = sidh.NewPrivateKey(sidh.FP_503, variant)
+	if prvKey.Generate(c.config.rand()) != nil {
+		return nil, keyShare{}, errors.New("tls: private SIDH key generation failed")
+	}
+	pubKey := prvKey.GeneratePublicKey()
+	return prvKey.Export(), keyShare{group: sidhP503, data: pubKey.Export()}, nil
+}
+
+func (kexSidhP503) derive(c *Conn, ks keyShare, key []byte) []byte {
+	var prvVariant, pubVariant = getSidhKeyVariant(c.isClient)
+	var prvKeySize = P503PrvKeySz
+
+	if len(ks.data) != P503PubKeySz || len(key) != prvKeySize {
+		return nil
+	}
+
+	prvKey := sidh.NewPrivateKey(sidh.FP_503, prvVariant)
+	pubKey := sidh.NewPublicKey(sidh.FP_503, pubVariant)
+
+	if err := prvKey.Import(key); err != nil {
+		return nil
+	}
+	if err := pubKey.Import(ks.data); err != nil {
+		return nil
+	}
+
+	// Never fails
+	sharedKey, _ := sidh.DeriveSecret(prvKey, pubKey)
+	return sharedKey
+}
+
+// KEX Hybrid SIDH/503-X25519
+func (kexHybridSidhP503X25519) generate(c *Conn, groupId CurveID) (private []byte, ks keyShare, err error) {
+	var pubHybrid [SidhP503Curve25519PubKeySz]byte
+	var prvHybrid [SidhP503Curve25519PrvKeySz]byte
+
+	// Generate ephemeral key for classic x25519
+	private, ks, err = dhKexStrat[X25519].generate(c, groupId)
+	if err != nil {
+		return
+	}
+	copy(prvHybrid[:], private)
+	copy(pubHybrid[:], ks.data)
+
+	// Generate PQ ephemeral key for SIDH
+	private, ks, err = dhKexStrat[sidhP503].generate(c, groupId)
+	if err != nil {
+		return
+	}
+	copy(prvHybrid[x25519SharedSecretSz:], private)
+	copy(pubHybrid[x25519SharedSecretSz:], ks.data)
+	return prvHybrid[:], keyShare{group: HybridSidhP503Curve25519, data: pubHybrid[:]}, nil
+}
+
+func (kexHybridSidhP503X25519) derive(c *Conn, ks keyShare, key []byte) []byte {
+	var sharedKey [SidhP503Curve25519SharedKeySz]byte
+	var ret []byte
+	var tmpKs keyShare
+
+	// Key agreement for classic
+	tmpKs.group = X25519
+	tmpKs.data = ks.data[:x25519SharedSecretSz]
+	ret = dhKexStrat[X25519].derive(c, tmpKs, key[:x25519SharedSecretSz])
+	if ret == nil {
+		return nil
+	}
+	copy(sharedKey[:], ret)
+
+	// Key agreement for PQ
+	tmpKs.group = sidhP503
+	tmpKs.data = ks.data[x25519SharedSecretSz:]
+	ret = dhKexStrat[sidhP503].derive(c, tmpKs, key[x25519SharedSecretSz:])
+	if ret == nil {
+		return nil
+	}
+	copy(sharedKey[x25519SharedSecretSz:], ret)
+	return sharedKey[:]
+}

_dev/Makefile

@@ -15,7 +15,7 @@ OS          ?= $(shell $(GO) env GOHOSTOS)
 ARCH        ?= $(shell $(GO) env GOHOSTARCH)
 OS_ARCH     := $(OS)_$(ARCH)
 VER_OS_ARCH := $(shell $(GO) version | cut -d' ' -f 3)_$(OS)_$(ARCH)
-GOROOT_ENV  := $(shell $(GO) env GOROOT)
+GOROOT_ENV  ?= $(shell $(GO) env GOROOT)
 GOROOT_LOCAL = $(BUILD_DIR)/$(OS_ARCH)
 # Flag indicates wheter invoke "go install -race std". Supported only on amd64 with CGO enabled
 INSTALL_RACE:= $(words $(filter $(ARCH)_$(shell go env CGO_ENABLED), amd64_1))
@@ -30,8 +30,10 @@ BOGO_DOCKER_TRIS_LOCATION=/go/src/github.com/cloudflare/tls-tris
 
 # SIDH repository (TODO: change path)
 SIDH_REPO  ?= https://github.com/cloudflare/sidh.git
+SIDH_REPO_TAG ?= 25c0d9f15d5e5bd5652b9741aeb50d9eb37154dc
 # NOBS repo (SIKE depends on SHA3)
 NOBS_REPO  ?= https://github.com/henrydcase/nobscrypto.git
+NOBS_REPO_TAG ?= 597f68906e981e61160b8c959b326596c0b240be
 
 ###############
 #
@@ -57,11 +59,13 @@ $(BUILD_DIR)/$(OS_ARCH)/.ok_$(VER_OS_ARCH): clean
 
 # Vendor NOBS library
 	$(GIT) clone $(NOBS_REPO) $(TMP_DIR)/nobs
+	cd $(TMP_DIR)/nobs; $(GIT) checkout $(NOBS_REPO_TAG)
 	cd $(TMP_DIR)/nobs; make vendor-sidh-for-tls
 	cp -rf $(TMP_DIR)/nobs/tls_vendor/* $(GOROOT_LOCAL)/src/vendor/
 
 # Vendor SIDH library
 	$(GIT) clone $(SIDH_REPO) $(TMP_DIR)/sidh
+	cd $(TMP_DIR)/sidh; $(GIT) checkout $(SIDH_REPO_TAG)
 	cd $(TMP_DIR)/sidh; make vendor
 	cp -rf $(TMP_DIR)/sidh/build/vendor/* $(GOROOT_LOCAL)/src/vendor/
 

_dev/interop_test_runner

@@ -216,12 +216,10 @@ class InteropServer_BoringSSL(InteropServer, ServerNominalMixin, ServerClientAut
         Checks wether ALPN is sent back by tris server in EncryptedExtensions in case of TLS 1.3. The
         ALPN protocol is set to 'npn_proto', which is hardcoded in TRIS test server.
         '''
-        res = self.d.run_client(self.CLIENT_NAME, self.server_ip+":1443 "+'-alpn-protos npn_proto -debug')
+        res = self.d.run_client(self.CLIENT_NAME, self.server_ip+":1443 "+'-alpn-protos npn_proto')
-        print(res[1])
         self.assertEqual(res[0], 0)
         self.assertIsNotNone(re.search(RE_PATTERN_ALPN, res[1], re.MULTILINE))
 
-
 # PicoTLS doesn't seem to implement draft-23 correctly. It will
 # be enabled when draft-28 is implemented.
 # class InteropServer_PicoTLS(
@@ -262,5 +260,17 @@ class InteropServer_TRIS(ClientNominalMixin, InteropServer, unittest.TestCase):
         res = self.d.run_client(self.CLIENT_NAME, '-rsa=false -ecdsa=false -cliauth '+self.server_ip+":6443")
         self.assertEqual(res[0], 0)
 
+    def test_qr(self):
+        res = self.d.run_client(self.CLIENT_NAME, '-rsa=false -ecdsa=true -qr SIDH-P503-X25519 '+self.server_ip+":7443")
+        self.assertEqual(res[0], 0)
+
+    def test_qrServerDoesntSupportSIDH(self):
+        '''
+        Client advertises HybridSIDH and ECDH. Server supports ECDH only. Checks weather
+        TLS session can still be established.
+        '''
+        res = self.d.run_client(self.CLIENT_NAME, '-rsa=false -ecdsa=true '+self.server_ip+":7443")
+        self.assertEqual(res[0], 0)
+
 if __name__ == '__main__':
     unittest.main()

_dev/tris-localserver/Dockerfile

@@ -8,6 +8,7 @@ EXPOSE 3443
 EXPOSE 4443
 EXPOSE 5443
 EXPOSE 6443
+EXPOSE 7443
 
 ADD tris-localserver /
 ADD runner.sh /

_dev/tris-localserver/runner.sh

@@ -6,5 +6,6 @@
 ./tris-localserver -b 0.0.0.0:4443 -cert=ecdsa -rtt0=oa 2>&1 &  # fourth port: offer and accept 0-RTT
 ./tris-localserver -b 0.0.0.0:5443 -cert=ecdsa -rtt0=oa -rtt0ack 2>&1 &  # fifth port: offer and accept 0-RTT but confirm
 ./tris-localserver -b 0.0.0.0:6443 -cert=rsa   -cliauth 2>&1 &  # sixth port: RSA with required client authentication
+./tris-localserver -b 0.0.0.0:7443 -cert=ecdsa -qr=c &          # Enables support for both - post-quantum and classical KEX algorithms
 
 wait

_dev/tris-localserver/server.go

@@ -55,6 +55,15 @@ func NewServer() *server {
 	return s
 }
 
+func enableQR(s *server, enableDefault bool) {
+	var sidhCurves = []tls.CurveID{tls.HybridSidhP503Curve25519}
+	if enableDefault {
+		var defaultCurvePreferences = []tls.CurveID{tls.X25519, tls.CurveP256, tls.CurveP384, tls.CurveP521}
+		s.TLS.CurvePreferences = append(s.TLS.CurvePreferences, defaultCurvePreferences...)
+	}
+	s.TLS.CurvePreferences = append(s.TLS.CurvePreferences, sidhCurves...)
+}
+
 func (s *server) start() {
 	var err error
 	if (s.ZeroRTT & ZeroRTT_Offer) == ZeroRTT_Offer {
@@ -144,6 +153,7 @@ func main() {
 	arg_zerortt := flag.String("rtt0", "n", `0-RTT, accepts following values [n: None, a: Accept, o: Offer, oa: Offer and Accept]`)
 	arg_confirm := flag.Bool("rtt0ack", false, "0-RTT confirm")
 	arg_clientauth := flag.Bool("cliauth", false, "Performs client authentication (RequireAndVerifyClientCert used)")
+	arg_qr := flag.String("qr", "", "Enable quantum-resistant algorithms [c: Support classical and Quantum-Resistant, q: Enable Quantum-Resistant only]")
 	flag.Parse()
 
 	s.Address = *arg_addr
@@ -162,6 +172,12 @@ func main() {
 		s.TLS.ClientAuth = tls.RequireAndVerifyClientCert
 	}
 
+	if *arg_qr == "c" {
+		enableQR(s, true)
+	} else if *arg_qr == "q" {
+		enableQR(s, false)
+	}
+
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		tlsConn := r.Context().Value(http.TLSConnContextKey).(*tls.Conn)
 

_dev/tris-testclient/client.go

@@ -51,6 +51,17 @@ func (c *Client) setMinMaxTLS(ver uint16) {
 	c.TLS.MaxVersion = ver
 }
 
+func getQrAlgoId(qr string) tls.CurveID {
+	switch qr {
+	case "SIDH-P503-X25519":
+		return tls.HybridSidhP503Curve25519
+	case "SIDH-P751-X448":
+		return tls.HybridSidhP751Curve448
+	default:
+		return 0
+	}
+}
+
 func (c *Client) run() {
 	fmt.Printf("TLS %s with %s\n", tlsVersionToName[c.TLS.MinVersion], cipherSuiteIdToName[c.TLS.CipherSuites[0]])
 
@@ -78,8 +89,7 @@ func (c *Client) run() {
 		failed++
 		return
 	}
-	fmt.Printf("Read %d bytes\n", n)
+	fmt.Printf("[TLS: %s] Read %d bytes\n", tlsVersionToName[con.ConnectionState().Version], n)
-
 	fmt.Println("OK\n")
 }
 
@@ -93,13 +103,14 @@ func result() {
 
 // Usage client args host:port
 func main() {
-	var keylog_file string
+	var keylog_file, qrAlgoName string
 	var enable_rsa, enable_ecdsa, client_auth bool
 
 	flag.StringVar(&keylog_file, "keylogfile", "", "Secrets will be logged here")
 	flag.BoolVar(&enable_rsa, "rsa", true, "Whether to enable RSA cipher suites")
 	flag.BoolVar(&enable_ecdsa, "ecdsa", true, "Whether to enable ECDSA cipher suites")
 	flag.BoolVar(&client_auth, "cliauth", false, "Whether to enable client authentication")
+	flag.StringVar(&qrAlgoName, "qr", "", "Specifies qr algorithm from following list:\n[SIDH-P503-X25519, SIDH-P751-X448]")
 	flag.Parse()
 	if flag.NArg() != 1 {
 		flag.Usage()
@@ -124,6 +135,21 @@ func main() {
 		log.Println("Enabled keylog")
 	}
 
+	if len(qrAlgoName) > 0 {
+		id := getQrAlgoId(qrAlgoName)
+		if id == 0 {
+			log.Fatalf("Unknown QR algorithm: %s", qrAlgoName)
+			return
+		}
+
+		client.TLS.CipherSuites = []uint16{tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256}
+		client.TLS.CurvePreferences = []tls.CurveID{id}
+		client.setMinMaxTLS(tls.VersionTLS13)
+		client.run()
+		result()
+		return
+	}
+
 	if client_auth {
 		var err error
 		client_cert, err := tls.X509KeyPair([]byte(client_crt), []byte(client_key))
@@ -145,6 +171,7 @@ func main() {
 		c.setMinMaxTLS(tls.VersionTLS12)
 		c.run()
 	}
+
 	if enable_ecdsa {
 		// Sane cipher suite for TLS 1.2 with an ECDSA cert (as used by boringssl)
 		c := client.clone()

common.go

@@ -116,10 +116,6 @@ const (
 type CurveID uint16
 
 const (
-	// Unexported
-	sidhP503 CurveID = 0
-	sidhP751 CurveID = 1
-
 	// Exported IDs
 	CurveP256 CurveID = 23
 	CurveP384 CurveID = 24
@@ -127,8 +123,12 @@ const (
 	X25519    CurveID = 29
 
 	// Experimental KEX
-	HybridSidhP503Curve25519 CurveID = 0x0105 + sidhP503 // HybridSIDH: X25519 + P503
+	HybridSidhP503Curve25519 CurveID = 0x0105 + (sidhP503 & 0xFF) // HybridSIDH: X25519 + P503
-	HybridSidhP751Curve448   CurveID = 0x0105 + sidhP751 // HybridSIDH: X448   + P751
+	HybridSidhP751Curve448   CurveID = 0x0105 + (sidhP751 & 0xFF) // HybridSIDH: X448   + P751
+
+	// Internal usage. Deliberately not exported
+	sidhP503 CurveID = 0xFE00
+	sidhP751 CurveID = 0xFE01
 )
 
 // TLS 1.3 Key Share