pske: add first version of post-quantum safe preshared key estasblishment feature

Signed-off-by: Steffen Vogel <post@steffenvogel.de>

cmd/cunicu/cmd.go

@@ -13,5 +13,6 @@ import (
 	_ "github.com/stv0g/cunicu/pkg/daemon/feature/hooks"
 	_ "github.com/stv0g/cunicu/pkg/daemon/feature/hsync"
 	_ "github.com/stv0g/cunicu/pkg/daemon/feature/pdisc"
+	_ "github.com/stv0g/cunicu/pkg/daemon/feature/pske"
 	_ "github.com/stv0g/cunicu/pkg/daemon/feature/rtsync"
 )

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/fsnotify/fsnotify v1.5.4
 	github.com/go-logr/logr v1.2.3
 	github.com/go-logr/zapr v1.2.3
+	github.com/go-piv/piv-go v1.10.0
 	github.com/google/nftables v0.0.0-20221002140148-535f5eb8da79
 	github.com/imdario/mergo v0.3.13
 	github.com/jpillora/backoff v1.0.0
@@ -21,6 +22,7 @@ require (
 	github.com/pion/stun v0.3.5
 	github.com/spf13/cobra v1.5.0
 	github.com/spf13/pflag v1.0.5
+	github.com/symbolicsoft/kyber-k2so v0.2.0
 	github.com/vishvananda/netlink v1.2.1-beta.2
 	go.uber.org/zap v1.23.0
 	golang.org/x/crypto v0.0.0-20221010152910-d6f0a8c073c2

go.sum

@@ -101,6 +101,8 @@ github.com/go-openapi/swag v0.22.3 h1:yMBqmnQ0gyZvEb/+KzuWZOXgllrXT4SADYbvDaXHv/
 github.com/go-openapi/swag v0.22.3/go.mod h1:UzaqsxGiab7freDnrUUra0MwWfN/q7tE4j+VcZ0yl14=
 github.com/go-ping/ping v1.1.0 h1:3MCGhVX4fyEUuhsfwPrsEdQw6xspHkv5zHsiSoDFZYw=
 github.com/go-ping/ping v1.1.0/go.mod h1:xIFjORFzTxqIV/tDVGO4eDy/bLuSyawEeojSm3GfRGk=
+github.com/go-piv/piv-go v1.10.0 h1:P1Y1VjBI5DnXW0+YkKmTuh5opWnMIrKriUaIOblee9Q=
+github.com/go-piv/piv-go v1.10.0/go.mod h1:NZ2zmjVkfFaL/CF8cVQ/pXdXtuj110zEKGdJM6fJZZM=
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
 github.com/go-test/deep v1.0.2-0.20181118220953-042da051cf31/go.mod h1:wGDj63lr65AM2AQyKZd/NYHGb0R+1RLqB8NKt3aSFNA=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
@@ -379,6 +381,8 @@ github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
 github.com/stv0g/gont v1.6.3 h1:7cIU2+F7iaGOHN9Mu2QKlKqZ4Dzk98Fu/P9gUPtjNFc=
 github.com/stv0g/gont v1.6.3/go.mod h1:Cl7BLHOE7YhWCPURgG0mvYBQBGGaNNQJeXSWNw+DJXs=
+github.com/symbolicsoft/kyber-k2so v0.2.0 h1:JHb3OzwV9xjSH/Sib4jd2swZzp2GNot8gUpdydqQBfs=
+github.com/symbolicsoft/kyber-k2so v0.2.0/go.mod h1:sfb01VbnBnAF3NJ0+k+Vh15N2tb0otGDxNfgE8al1is=
 github.com/vishvananda/netlink v1.2.1-beta.2 h1:Llsql0lnQEbHj0I1OuKyp8otXp0r3q0mPkuhwHfStVs=
 github.com/vishvananda/netlink v1.2.1-beta.2/go.mod h1:twkDnbuQxJYemMlGd4JFIcuhgX83tXhKS2B/PRMpOho=
 github.com/vishvananda/netns v0.0.0-20200728191858-db3c7e526aae/go.mod h1:DD4vA1DwXk04H54A1oHXtwZmA0grkVMdPxx/VGLCah0=
@@ -411,6 +415,7 @@ golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACk
 golang.org/x/crypto v0.0.0-20190923035154-9ee001bba392/go.mod h1:/lpIB1dKB+9EgE3H3cr1v9wB50oz8l4C4h62xy7jSTY=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20210322153248-0c34fe9e7dc2/go.mod h1:T9bdIzuCu7OtxOm1hfPfRQxPLYneinmdGuTeoZ9dtd4=
 golang.org/x/crypto v0.0.0-20220427172511-eb4f295cb31f/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
 golang.org/x/crypto v0.0.0-20221010152910-d6f0a8c073c2 h1:x8vtB3zMecnlqZIwJNUUpwYKYSqCz5jXbiyv0ZJJZeI=
 golang.org/x/crypto v0.0.0-20221010152910-d6f0a8c073c2/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=

pkg/config/defaults.go

@@ -51,12 +51,13 @@ var (
 	}
 
 	DefaultInterfaceSettings = InterfaceSettings{
-		DiscoverPeers:     true,
-		DiscoverEndpoints: true,
-		SyncConfig:        true,
-		SyncHosts:         true,
-		SyncRoutes:        true,
-		WatchRoutes:       true,
+		DiscoverPeers:          true,
+		DiscoverEndpoints:      true,
+		SyncConfig:             true,
+		SyncHosts:              true,
+		SyncRoutes:             true,
+		WatchRoutes:            true,
+		EstablishPresharedKeys: true,
 
 		ICE: ICESettings{
 			URLs:                DefaultICEURLs,

pkg/config/settings.go

@@ -117,11 +117,12 @@ type InterfaceSettings struct {
 	Peers           map[string]PeerSettings `koanf:"peers,omitempty"`
 
 	// Feature flags
-	DiscoverEndpoints bool `koanf:"discover_endpoints,omitempty"`
-	DiscoverPeers     bool `koanf:"discover_peers,omitempty"`
-	SyncConfig        bool `koanf:"sync_config,omitempty"`
-	SyncRoutes        bool `koanf:"sync_routes,omitempty"`
-	SyncHosts         bool `koanf:"sync_hosts,omitempty"`
+	DiscoverEndpoints      bool `koanf:"discover_endpoints,omitempty"`
+	DiscoverPeers          bool `koanf:"discover_peers,omitempty"`
+	SyncConfig             bool `koanf:"sync_config,omitempty"`
+	SyncRoutes             bool `koanf:"sync_routes,omitempty"`
+	SyncHosts              bool `koanf:"sync_hosts,omitempty"`
+	EstablishPresharedKeys bool `koanf:"establish_psk,omitempty"`
 
 	WatchConfig bool `koanf:"watch_config,omitempty"`
 	WatchRoutes bool `koanf:"watch_routes,omitempty"`

pkg/daemon/feature/pske/handlers.go

@@ -0,0 +1,17 @@
+package pske
+
+import (
+	"github.com/stv0g/cunicu/pkg/core"
+	"go.uber.org/zap"
+)
+
+func (i *Interface) OnPeerAdded(cp *core.Peer) {
+	if cp.PresharedKey().IsSet() {
+		i.logger.Debug("Ignoring peer as it already has a PSK configured", zap.Any("peer", cp))
+		return
+	}
+
+	i.Peers[cp] = i.NewPeer(cp, i)
+}
+
+func (i *Interface) OnPeerRemoved(p *core.Peer) {}

pkg/daemon/feature/pske/peer.go

@@ -0,0 +1,128 @@
+package pske
+
+import (
+	"context"
+
+	kyber "github.com/symbolicsoft/kyber-k2so"
+	"go.uber.org/zap"
+
+	"github.com/stv0g/cunicu/pkg/core"
+	"github.com/stv0g/cunicu/pkg/crypto"
+	"github.com/stv0g/cunicu/pkg/signaling"
+
+	pskeproto "github.com/stv0g/cunicu/pkg/proto/feature/pske"
+)
+
+type Peer struct {
+	*core.Peer
+
+	Interface *Interface
+
+	SecretKey KyberSecretKey
+
+	logger *zap.Logger
+}
+
+func (i *Interface) NewPeer(cp *core.Peer, kem *Interface) *Peer {
+	p := &Peer{
+		Peer:      cp,
+		Interface: i,
+
+		logger: i.logger.With(zap.String("peer", cp.String())),
+	}
+
+	go p.EstablishPSK()
+
+	return p
+}
+
+func (p *Peer) EstablishPSK() {
+	var err error
+
+	ctx := context.Background()
+	kp := p.PublicPrivateKeyPair()
+
+	if _, err := p.Interface.Daemon.Backend.Subscribe(ctx, kp, p); err != nil {
+		p.logger.Error("Failed to subscribe to message", zap.Error(err))
+		return
+	}
+
+	if p.IsControlling() {
+		var pk KyberPublicKey
+
+		// Generate new key pair
+		if p.SecretKey, pk, err = kyber.KemKeypair1024(); err != nil {
+			p.logger.Error("Failed to generate Kyber key pair", zap.Error(err))
+		}
+
+		// Send public key
+		msg := signaling.Message{
+			Pske: &pskeproto.PresharedKeyEstablishment{
+				PublicKey: pk[:],
+			},
+		}
+
+		if err := p.Interface.Daemon.Backend.Publish(ctx, kp, &msg); err != nil {
+			p.logger.Error("Failed to publish public key", zap.Error(err))
+		}
+	}
+}
+
+func (p *Peer) OnSignalingMessage(kp *crypto.PublicKeyPair, msg *signaling.Message) {
+	if msg.Pske == nil {
+		return
+	}
+
+	var err error
+	var psk crypto.Key
+
+	if p.IsControlling() {
+		if msg.Pske.CipherText == nil {
+			p.logger.Error("Expected cipher text")
+			return
+		}
+
+		if ctLen := len(msg.Pske.CipherText); ctLen != kyber.Kyber1024CTBytes {
+			p.logger.Error("Invalid cipher text length", zap.Int("len", ctLen))
+			return
+		}
+
+		// Decrypt cipher text
+		ct := *(*KyberCipherText)(msg.Pske.CipherText)
+		if psk, err = kyber.KemDecrypt1024(ct, p.SecretKey); err != nil {
+			p.logger.Error("Failed to decrypt PSK", zap.Error(err))
+			return
+		}
+	} else {
+		if msg.Pske.PublicKey == nil {
+			p.logger.Error("Expected public key")
+			return
+		}
+
+		var ct KyberCipherText
+
+		// Encrypt cipher text
+		pk := *(*KyberPublicKey)(msg.Pske.PublicKey)
+		if ct, psk, err = kyber.KemEncrypt1024(pk); err != nil {
+			p.logger.Error("Failed to encrypt cipher text", zap.Error(err))
+			return
+		}
+
+		// Publish cipher text
+		ctx := context.Background()
+		kp := p.PublicPrivateKeyPair()
+		msg := &signaling.Message{
+			Pske: &pskeproto.PresharedKeyEstablishment{
+				CipherText: ct[:],
+			},
+		}
+
+		if err := p.Interface.Daemon.Backend.Publish(ctx, kp, msg); err != nil {
+			p.logger.Error("Failed to publish cipher text", zap.Error(err))
+		}
+	}
+
+	if err := p.SetPresharedKey(&psk); err != nil {
+		p.logger.Error("Failed to update preshared key", zap.Error(err))
+	}
+}

pkg/daemon/feature/pske/piv.go_

@@ -0,0 +1,130 @@
+package pske
+
+import (
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/go-piv/piv-go/piv"
+)
+
+func main() {
+	if len(os.Args) < 2 {
+		return
+	}
+
+	// List all smart cards connected to the system.
+	cards, err := piv.Cards()
+	if err != nil {
+		panic(err)
+	}
+
+	// Find a YubiKey and open the reader.
+	var yk *piv.YubiKey
+	for _, card := range cards {
+		if strings.Contains(strings.ToLower(card), "yubikey") {
+			if yk, err = piv.Open(card); err != nil {
+				panic(err)
+			}
+			break
+		}
+	}
+	if yk == nil {
+		panic("no yubikey found")
+	}
+
+	defer yk.Close()
+
+	switch os.Args[1] {
+	case "cert":
+		cert(yk)
+	case "decrypt":
+		decrypt(yk)
+	case "encrypt":
+		encrypt(yk)
+	}
+}
+
+func cert(yk *piv.YubiKey) {
+
+	// sn, _ := yk.Serial()
+	// fmt.Printf("Version: %d.%d.%d\n", yk.Version().Major, yk.Version().Minor, yk.Version().Patch)
+	// fmt.Printf("Serial: %d\n", sn)
+
+	crt, err := yk.Certificate(piv.SlotSignature)
+	if err != nil {
+		panic(err)
+	}
+
+	// Print the certificate
+	// result, err := certinfo.CertificateText(crt)
+	// if err != nil {
+	// 	log.Fatal(err)
+	// }
+	// fmt.Print(result)
+
+	pemPayload, _ := x509.MarshalPKIXPublicKey(crt.PublicKey.(*rsa.PublicKey))
+
+	pem.Encode(os.Stdout, &pem.Block{
+		Type:  "PUBLIC KEY",
+		Bytes: pemPayload,
+	})
+}
+
+func encrypt(yk *piv.YubiKey) {
+	pt, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		panic(err)
+	}
+
+	crt, err := yk.Certificate(piv.SlotSignature)
+	if err != nil {
+		panic(err)
+	}
+
+	pk := crt.PublicKey.(*rsa.PublicKey)
+
+	ct, err := rsa.EncryptPKCS1v15(rand.Reader, pk, pt)
+	if err != nil {
+		panic(err)
+	}
+
+	os.Stdout.Write(ct)
+}
+
+func decrypt(yk *piv.YubiKey) {
+	ct, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		panic(err)
+	}
+
+	crt, err := yk.Certificate(piv.SlotSignature)
+	if err != nil {
+		panic(err)
+	}
+
+	sk, err := yk.PrivateKey(piv.SlotSignature, crt.PublicKey, piv.KeyAuth{
+		PIN: "0000",
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	dec, ok := sk.(crypto.Decrypter)
+	if !ok {
+		panic("no rsa key?")
+	}
+
+	pt, err := dec.Decrypt(rand.Reader, ct, nil)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Print(string(pt))
+}

pkg/daemon/feature/pske/pske.go

@@ -0,0 +1,43 @@
+// Package pske uses the Kyber Key Establishment Mechanism (KEM) to establish Preshared Keys (PSKs) between two WireGuard peers
+package pske
+
+import (
+	"github.com/stv0g/cunicu/pkg/core"
+	"github.com/stv0g/cunicu/pkg/daemon"
+	"go.uber.org/zap"
+)
+
+func init() {
+	daemon.RegisterFeature("pske", "Preshared key establishment ", New, 110)
+}
+
+type Interface struct {
+	*daemon.Interface
+
+	Peers map[*core.Peer]*Peer
+
+	logger *zap.Logger
+}
+
+func New(i *daemon.Interface) (daemon.Feature, error) {
+	if !i.Settings.EstablishPresharedKeys {
+		return nil, nil
+	}
+
+	p := &Interface{
+		Interface: i,
+		Peers:     map[*core.Peer]*Peer{},
+
+		logger: zap.L().Named("pske").With(zap.String("intf", i.Name())),
+	}
+
+	i.OnPeer(p)
+
+	return p, nil
+}
+
+func (i *Interface) Start() error {
+	i.logger.Info("Started post-quantum preshared key establishment")
+
+	return nil
+}

pkg/daemon/feature/pske/types.go

@@ -0,0 +1,7 @@
+package pske
+
+import kyber "github.com/symbolicsoft/kyber-k2so"
+
+type KyberCipherText [kyber.Kyber1024CTBytes]byte
+type KyberPublicKey [kyber.Kyber1024PKBytes]byte
+type KyberSecretKey [kyber.Kyber1024SKBytes]byte

pkg/proto/proto.go

@@ -5,7 +5,7 @@ package proto
 //go:generate protoc --proto_path=../../proto --go_out=.      --go_opt=paths=import,module=github.com/stv0g/cunicu/pkg/proto core/peer.proto core/interface.proto core/net.proto
 //go:generate protoc --proto_path=../../proto --go_out=.      --go_opt=paths=import,module=github.com/stv0g/cunicu/pkg/proto signaling/signaling.proto signaling/relay.proto
 //go:generate protoc --proto_path=../../proto --go_out=.      --go_opt=paths=import,module=github.com/stv0g/cunicu/pkg/proto rpc/daemon.proto rpc/epdisc.proto rpc/event.proto rpc/signaling.proto rpc/invitation.proto
-//go:generate protoc --proto_path=../../proto --go_out=.      --go_opt=paths=import,module=github.com/stv0g/cunicu/pkg/proto feature/epdisc.proto feature/epdisc_candidate.proto feature/pdisc.proto feature/pske.proto feature/hooks.proto
+//go:generate protoc --proto_path=../../proto --go_out=.      --go_opt=paths=import,module=github.com/stv0g/cunicu/pkg/proto feature/epdisc.proto feature/epdisc_candidate.proto feature/pdisc.proto feature/pske.proto feature/hooks.proto feature/pske.proto
 
 //go:generate protoc --proto_path=../../proto --go-grpc_out=. --go-grpc_opt=paths=import,module=github.com/stv0g/cunicu/pkg/proto rpc/daemon.proto rpc/epdisc.proto rpc/signaling.proto
 //go:generate protoc --proto_path=../../proto --go-grpc_out=. --go-grpc_opt=paths=import,module=github.com/stv0g/cunicu/pkg/proto signaling/signaling.proto signaling/relay.proto