Extract common server encryption logic (#65)

* refactor: extract common message encryption logic
* refactor: move letsencrypt logic to common
* refactor: rename common package to encryption
* test: add encryption tests

encryption/encryption.go

@@ -0,0 +1,50 @@
+package encryption
+
+import (
+	"crypto/rand"
+	"fmt"
+	"golang.org/x/crypto/nacl/box"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+)
+
+// A set of tools to encrypt/decrypt messages being sent through the Signal Exchange Service or Management Service
+// These tools use Golang crypto package (Curve25519, XSalsa20 and Poly1305 to encrypt and authenticate)
+// Wireguard keys are used for encryption
+
+// Encrypt encrypts a message using local Wireguard private key and remote peer's public key.
+func Encrypt(msg []byte, peerPublicKey wgtypes.Key, privateKey wgtypes.Key) ([]byte, error) {
+	nonce, err := genNonce()
+	if err != nil {
+		return nil, err
+	}
+	return box.Seal(nonce[:], msg, nonce, toByte32(peerPublicKey), toByte32(privateKey)), nil
+}
+
+// Decrypt decrypts a message that has been encrypted by the remote peer using Wireguard private key and remote peer's public key.
+func Decrypt(encryptedMsg []byte, peerPublicKey wgtypes.Key, privateKey wgtypes.Key) ([]byte, error) {
+	nonce, err := genNonce()
+	if err != nil {
+		return nil, err
+	}
+	copy(nonce[:], encryptedMsg[:24])
+	opened, ok := box.Open(nil, encryptedMsg[24:], nonce, toByte32(peerPublicKey), toByte32(privateKey))
+	if !ok {
+		return nil, fmt.Errorf("failed to decrypt message from peer %s", peerPublicKey.String())
+	}
+
+	return opened, nil
+}
+
+// Generates nonce of size 24
+func genNonce() (*[24]byte, error) {
+	var nonce [24]byte
+	if _, err := rand.Read(nonce[:]); err != nil {
+		return nil, err
+	}
+	return &nonce, nil
+}
+
+// Converts Wireguard key to byte array of size 32 (a format used by the golang crypto package)
+func toByte32(key wgtypes.Key) *[32]byte {
+	return (*[32]byte)(&key)
+}

encryption/encryption_suite_test.go

@@ -0,0 +1,13 @@
+package encryption_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"testing"
+)
+
+func TestManagement(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Management Service Suite")
+}

encryption/encryption_test.go

@@ -0,0 +1,60 @@
+package encryption_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"github.com/wiretrustee/wiretrustee/encryption"
+	"github.com/wiretrustee/wiretrustee/encryption/testprotos"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+)
+
+const ()
+
+var _ = Describe("Encryption", func() {
+
+	var (
+		encryptionKey wgtypes.Key
+		decryptionKey wgtypes.Key
+	)
+
+	BeforeEach(func() {
+		var err error
+		encryptionKey, err = wgtypes.GenerateKey()
+		Expect(err).NotTo(HaveOccurred())
+		decryptionKey, err = wgtypes.GenerateKey()
+		Expect(err).NotTo(HaveOccurred())
+	})
+
+	Context("decrypting a plain message", func() {
+		Context("when it was encrypted with Wireguard keys", func() {
+			Specify("should be successful", func() {
+				msg := "message"
+				encryptedMsg, err := encryption.Encrypt([]byte(msg), decryptionKey.PublicKey(), encryptionKey)
+				Expect(err).NotTo(HaveOccurred())
+
+				decryptedMsg, err := encryption.Decrypt(encryptedMsg, encryptionKey.PublicKey(), decryptionKey)
+				Expect(err).NotTo(HaveOccurred())
+
+				Expect(string(decryptedMsg)).To(BeEquivalentTo(msg))
+			})
+		})
+	})
+
+	Context("decrypting a protobuf message", func() {
+		Context("when it was encrypted with Wireguard keys", func() {
+			Specify("should be successful", func() {
+
+				protoMsg := &testprotos.TestMessage{Body: "message"}
+				encryptedMsg, err := encryption.EncryptMessage(decryptionKey.PublicKey(), encryptionKey, protoMsg)
+				Expect(err).NotTo(HaveOccurred())
+
+				decryptedMsg := &testprotos.TestMessage{}
+				err = encryption.DecryptMessage(encryptionKey.PublicKey(), decryptionKey, encryptedMsg, decryptedMsg)
+				Expect(err).NotTo(HaveOccurred())
+
+				Expect(decryptedMsg.GetBody()).To(BeEquivalentTo(protoMsg.GetBody()))
+			})
+		})
+	})
+
+})

encryption/letsencrypt.go

@@ -0,0 +1,40 @@
+package encryption
+
+import (
+	"crypto/tls"
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/crypto/acme/autocert"
+	"net/http"
+	"os"
+	"path/filepath"
+)
+
+// EnableLetsEncrypt wraps common logic of generating Let's encrypt certificate.
+// Includes a HTTP handler and listener to solve the Let's encrypt challenge
+func EnableLetsEncrypt(datadir string, letsencryptDomain string) *tls.Config {
+	certDir := filepath.Join(datadir, "letsencrypt")
+
+	if _, err := os.Stat(certDir); os.IsNotExist(err) {
+		err = os.MkdirAll(certDir, os.ModeDir)
+		if err != nil {
+			log.Fatalf("failed creating Let's encrypt certdir: %s: %v", certDir, err)
+		}
+	}
+
+	log.Infof("running with Let's encrypt with domain %s. Cert will be stored in %s", letsencryptDomain, certDir)
+
+	certManager := autocert.Manager{
+		Prompt:     autocert.AcceptTOS,
+		Cache:      autocert.DirCache(certDir),
+		HostPolicy: autocert.HostWhitelist(letsencryptDomain),
+	}
+
+	// listener to handle Let's encrypt certificate challenge
+	go func() {
+		if err := http.Serve(certManager.Listener(), certManager.HTTPHandler(nil)); err != nil {
+			log.Fatalf("failed to serve letsencrypt handler: %v", err)
+		}
+	}()
+
+	return &tls.Config{GetCertificate: certManager.GetCertificate}
+}

encryption/message.go

@@ -0,0 +1,40 @@
+package encryption
+
+import (
+	pb "github.com/golang/protobuf/proto" //nolint
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+)
+
+// EncryptMessage encrypts a body of the given protobuf Message
+func EncryptMessage(remotePubKey wgtypes.Key, ourPrivateKey wgtypes.Key, message pb.Message) ([]byte, error) {
+	byteResp, err := pb.Marshal(message)
+	if err != nil {
+		log.Errorf("failed marshalling message %v", err)
+		return nil, err
+	}
+
+	encryptedBytes, err := Encrypt(byteResp, remotePubKey, ourPrivateKey)
+	if err != nil {
+		log.Errorf("failed encrypting SyncResponse %v", err)
+		return nil, err
+	}
+
+	return encryptedBytes, nil
+}
+
+// DecryptMessage decrypts an encrypted message into given protobuf Message
+func DecryptMessage(remotePubKey wgtypes.Key, ourPrivateKey wgtypes.Key, encryptedMessage []byte, message pb.Message) error {
+	decrypted, err := Decrypt(encryptedMessage, remotePubKey, ourPrivateKey)
+	if err != nil {
+		log.Warnf("error while decrypting Sync request message from peer %s", remotePubKey.String())
+		return err
+	}
+
+	err = pb.Unmarshal(decrypted, message)
+	if err != nil {
+		log.Warnf("error while umarshalling Sync request message from peer %s", remotePubKey.String())
+		return err
+	}
+	return nil
+}

encryption/testprotos/generate.sh

@@ -0,0 +1,2 @@
+#!/bin/bash
+protoc -I testprotos/ testprotos/testproto.proto --go_out=.

encryption/testprotos/testproto.pb.go

@@ -0,0 +1,142 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.26.0
+// 	protoc        v3.12.4
+// source: testproto.proto
+
+package testprotos
+
+import (
+	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
+	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
+	reflect "reflect"
+	sync "sync"
+)
+
+const (
+	// Verify that this generated code is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
+	// Verify that runtime/protoimpl is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
+)
+
+type TestMessage struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	Body string `protobuf:"bytes,1,opt,name=body,proto3" json:"body,omitempty"`
+}
+
+func (x *TestMessage) Reset() {
+	*x = TestMessage{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_testproto_proto_msgTypes[0]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *TestMessage) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*TestMessage) ProtoMessage() {}
+
+func (x *TestMessage) ProtoReflect() protoreflect.Message {
+	mi := &file_testproto_proto_msgTypes[0]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use TestMessage.ProtoReflect.Descriptor instead.
+func (*TestMessage) Descriptor() ([]byte, []int) {
+	return file_testproto_proto_rawDescGZIP(), []int{0}
+}
+
+func (x *TestMessage) GetBody() string {
+	if x != nil {
+		return x.Body
+	}
+	return ""
+}
+
+var File_testproto_proto protoreflect.FileDescriptor
+
+var file_testproto_proto_rawDesc = []byte{
+	0x0a, 0x0f, 0x74, 0x65, 0x73, 0x74, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2e, 0x70, 0x72, 0x6f, 0x74,
+	0x6f, 0x12, 0x0a, 0x74, 0x65, 0x73, 0x74, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x73, 0x22, 0x21, 0x0a,
+	0x0b, 0x54, 0x65, 0x73, 0x74, 0x4d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x12, 0x12, 0x0a, 0x04,
+	0x62, 0x6f, 0x64, 0x79, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x04, 0x62, 0x6f, 0x64, 0x79,
+	0x42, 0x0d, 0x5a, 0x0b, 0x2f, 0x74, 0x65, 0x73, 0x74, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x73, 0x62,
+	0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
+}
+
+var (
+	file_testproto_proto_rawDescOnce sync.Once
+	file_testproto_proto_rawDescData = file_testproto_proto_rawDesc
+)
+
+func file_testproto_proto_rawDescGZIP() []byte {
+	file_testproto_proto_rawDescOnce.Do(func() {
+		file_testproto_proto_rawDescData = protoimpl.X.CompressGZIP(file_testproto_proto_rawDescData)
+	})
+	return file_testproto_proto_rawDescData
+}
+
+var file_testproto_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
+var file_testproto_proto_goTypes = []interface{}{
+	(*TestMessage)(nil), // 0: testprotos.TestMessage
+}
+var file_testproto_proto_depIdxs = []int32{
+	0, // [0:0] is the sub-list for method output_type
+	0, // [0:0] is the sub-list for method input_type
+	0, // [0:0] is the sub-list for extension type_name
+	0, // [0:0] is the sub-list for extension extendee
+	0, // [0:0] is the sub-list for field type_name
+}
+
+func init() { file_testproto_proto_init() }
+func file_testproto_proto_init() {
+	if File_testproto_proto != nil {
+		return
+	}
+	if !protoimpl.UnsafeEnabled {
+		file_testproto_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*TestMessage); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+	}
+	type x struct{}
+	out := protoimpl.TypeBuilder{
+		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
+			RawDescriptor: file_testproto_proto_rawDesc,
+			NumEnums:      0,
+			NumMessages:   1,
+			NumExtensions: 0,
+			NumServices:   0,
+		},
+		GoTypes:           file_testproto_proto_goTypes,
+		DependencyIndexes: file_testproto_proto_depIdxs,
+		MessageInfos:      file_testproto_proto_msgTypes,
+	}.Build()
+	File_testproto_proto = out.File
+	file_testproto_proto_rawDesc = nil
+	file_testproto_proto_goTypes = nil
+	file_testproto_proto_depIdxs = nil
+}

encryption/testprotos/testproto.proto

@@ -0,0 +1,9 @@
+syntax = "proto3";
+
+option go_package = "/testprotos";
+
+package testprotos;
+
+message TestMessage {
+  string body = 1;
+}