add digital signature challenge response authentication mechanism

using ed25519 keypairs

Signed-off-by: Fabian Deifuß <deifussfabian@icloud.com>

clientapi/auth/authtypes/logintypes.go

@@ -7,6 +7,7 @@ type LoginType string
 const (
 	LoginTypePassword           = "m.login.password"
 	LoginTypeDummy              = "m.login.dummy"
+	LoginTypeChallengeResponse  = "m.login.challenge_response"
 	LoginTypeSharedSecret       = "org.matrix.login.shared_secret"
 	LoginTypeRecaptcha          = "m.login.recaptcha"
 	LoginTypeApplicationService = "m.login.application_service"

clientapi/auth/challenge_response.go

@@ -0,0 +1,67 @@
+package auth
+
+import (
+	"context"
+	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/clientapi/userutil"
+	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/util"
+	"net/http"
+)
+
+type GetAccountByChallengeResponse func(ctx context.Context, localpart, b64encodedSignature, challenge string) (*api.Account, error)
+
+type ChallengeResponseRequest struct {
+	Login
+	Signature string `json:"signature"`
+}
+
+// LoginTypeChallengeResponse using public key encryption
+type LoginTypeChallengeResponse struct {
+	GetAccountByChallengeResponse GetAccountByChallengeResponse
+	Config                        *config.ClientAPI
+}
+
+func (t *LoginTypeChallengeResponse) Name() string {
+	return authtypes.LoginTypeChallengeResponse
+}
+
+func (t *LoginTypeChallengeResponse) Request() interface{} {
+	return &ChallengeResponseRequest{}
+}
+
+func (t *LoginTypeChallengeResponse) Login(ctx context.Context, req interface{}, challenge string) (*Login, *util.JSONResponse) {
+	r := req.(*ChallengeResponseRequest)
+	username := r.Username()
+	if username == "" {
+		return nil, &util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("A username must be supplied."),
+		}
+	}
+	localpart, err := userutil.ParseUsernameParam(username, &t.Config.Matrix.ServerName)
+	if err != nil {
+		return nil, &util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.InvalidUsername(err.Error()),
+		}
+	}
+	if r.Signature == "" {
+		return nil, &util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.InvalidSignature("No signature provided"),
+		}
+	}
+	_, err = t.GetAccountByChallengeResponse(ctx, localpart, r.Signature, challenge)
+	if err != nil {
+		// Technically we could tell them if the user does not exist by checking if err == sql.ErrNoRows
+		// but that would leak the existence of the user.
+		return nil, &util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden("The digital signature is incorrect or the account does not exist."),
+		}
+	}
+	return &r.Login, nil
+}

clientapi/auth/password.go

@@ -47,7 +47,7 @@ func (t *LoginTypePassword) Request() interface{} {
 	return &PasswordRequest{}
 }
 
-func (t *LoginTypePassword) Login(ctx context.Context, req interface{}) (*Login, *util.JSONResponse) {
+func (t *LoginTypePassword) Login(ctx context.Context, req interface{}, challenge string) (*Login, *util.JSONResponse) {
 	r := req.(*PasswordRequest)
 	// Squash username to all lowercase letters
 	username := strings.ToLower(r.Username())

clientapi/auth/user_interactive.go

@@ -17,14 +17,15 @@ package auth
 import (
 	"context"
 	"encoding/json"
-	"net/http"
+	"fmt"
-
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/userapi/api"
 	"github.com/matrix-org/util"
 	"github.com/sirupsen/logrus"
 	"github.com/tidwall/gjson"
+	"net/http"
+	"time"
 )
 
 // Type represents an auth type
@@ -43,7 +44,7 @@ type Type interface {
 	// "If the homeserver decides that an attempt on a stage was unsuccessful, but the
 	// client may make a second attempt, it returns the same HTTP status 401 response as above,
 	// with the addition of the standard errcode and error fields describing the error."
-	Login(ctx context.Context, req interface{}) (login *Login, errRes *util.JSONResponse)
+	Login(ctx context.Context, req interface{}, challenge string) (login *Login, errRes *util.JSONResponse)
 	// TODO: Extend to support Register() flow
 	// Register(ctx context.Context, sessionID string, req interface{})
 }
@@ -109,13 +110,18 @@ type UserInteractive struct {
 	Types map[string]Type
 	// Map of session ID to completed login types, will need to be extended in future
 	Sessions      map[string][]string
+	SessionParams map[string]map[string]string
 }
 
-func NewUserInteractive(getAccByPass GetAccountByPassword, cfg *config.ClientAPI) *UserInteractive {
+func NewUserInteractive(getAccByPass GetAccountByPassword, getAccByChallengeResponse GetAccountByChallengeResponse, cfg *config.ClientAPI) *UserInteractive {
 	typePassword := &LoginTypePassword{
 		GetAccountByPassword: getAccByPass,
 		Config:               cfg,
 	}
+	typeChallengeResponse := &LoginTypeChallengeResponse{
+		GetAccountByChallengeResponse: getAccByChallengeResponse,
+		Config:                        cfg,
+	}
 	// TODO: Add SSO login
 	return &UserInteractive{
 		Completed: []string{},
@@ -123,11 +129,16 @@ func NewUserInteractive(getAccByPass GetAccountByPassword, cfg *config.ClientAPI
 			{
 				Stages: []string{typePassword.Name()},
 			},
+			{
+				Stages: []string{typeChallengeResponse.Name()},
+			},
 		},
 		Types: map[string]Type{
 			typePassword.Name():          typePassword,
+			typeChallengeResponse.Name(): typeChallengeResponse,
 		},
 		Sessions:      make(map[string][]string),
+		SessionParams: make(map[string]map[string]string),
 	}
 }
 
@@ -148,6 +159,9 @@ func (u *UserInteractive) AddCompletedStage(sessionID, authType string) {
 
 // Challenge returns an HTTP 401 with the supported flows for authenticating
 func (u *UserInteractive) Challenge(sessionID string) *util.JSONResponse {
+	params := make(map[string]string)
+	params["challenge"] = fmt.Sprintf("%d%s", time.Now().Unix(), sessionID)
+	u.SessionParams[sessionID] = params
 	return &util.JSONResponse{
 		Code: 401,
 		JSON: struct {
@@ -155,18 +169,18 @@ func (u *UserInteractive) Challenge(sessionID string) *util.JSONResponse {
 			Flows     []userInteractiveFlow `json:"flows"`
 			Session   string                `json:"session"`
 			// TODO: Return any additional `params`
-			Params map[string]interface{} `json:"params"`
+			Params map[string]string `json:"params"`
 		}{
 			u.Completed,
 			u.Flows,
 			sessionID,
-			make(map[string]interface{}),
+			params,
 		},
 	}
 }
 
 // NewSession returns a challenge with a new session ID and remembers the session ID
-func (u *UserInteractive) NewSession() *util.JSONResponse {
+func (u *UserInteractive) NewSession(authType string) *util.JSONResponse {
 	sessionID, err := GenerateAccessToken()
 	if err != nil {
 		logrus.WithError(err).Error("failed to generate session ID")
@@ -207,15 +221,16 @@ func (u *UserInteractive) ResponseWithChallenge(sessionID string, response inter
 func (u *UserInteractive) Verify(ctx context.Context, bodyBytes []byte, device *api.Device) (*Login, *util.JSONResponse) {
 	// TODO: rate limit
 
+	// extract the type so we know which login type to use
+	authType := gjson.GetBytes(bodyBytes, "auth.type").Str
+
 	// "A client should first make a request with no auth parameter. The homeserver returns an HTTP 401 response, with a JSON body"
 	// https://matrix.org/docs/spec/client_server/r0.6.1#user-interactive-api-in-the-rest-api
 	hasResponse := gjson.GetBytes(bodyBytes, "auth").Exists()
 	if !hasResponse {
-		return nil, u.NewSession()
+		return nil, u.NewSession(authType)
 	}
 
-	// extract the type so we know which login type to use
-	authType := gjson.GetBytes(bodyBytes, "auth.type").Str
 	loginType, ok := u.Types[authType]
 	if !ok {
 		return nil, &util.JSONResponse{
@@ -237,13 +252,13 @@ func (u *UserInteractive) Verify(ctx context.Context, bodyBytes []byte, device *
 	}
 
 	r := loginType.Request()
-	if err := json.Unmarshal([]byte(gjson.GetBytes(bodyBytes, "auth").Raw), r); err != nil {
+	if err := json.Unmarshal(bodyBytes, r); err != nil {
 		return nil, &util.JSONResponse{
 			Code: http.StatusBadRequest,
 			JSON: jsonerror.BadJSON("The request body could not be decoded into valid JSON. " + err.Error()),
 		}
 	}
-	login, resErr := loginType.Login(ctx, r)
+	login, resErr := loginType.Login(ctx, r, u.SessionParams[sessionID]["challenge"])
 	if resErr == nil {
 		u.AddCompletedStage(sessionID, authType)
 		// TODO: Check if there's more stages to go and return an error

clientapi/auth/user_interactive_test.go

@@ -32,13 +32,21 @@ func getAccountByPassword(ctx context.Context, localpart, plaintextPassword stri
 	return acc, nil
 }
 
+func getAccountByChallengeResponse(ctx context.Context, localpart, b64encodedSignature, challenge string) (*api.Account, error) {
+	acc, ok := lookup[localpart+" "+b64encodedSignature+" "+challenge]
+	if !ok {
+		return nil, fmt.Errorf("unknown user/pubkey")
+	}
+	return acc, nil
+}
+
 func setup() *UserInteractive {
 	cfg := &config.ClientAPI{
 		Matrix: &config.Global{
 			ServerName: serverName,
 		},
 	}
-	return NewUserInteractive(getAccountByPassword, cfg)
+	return NewUserInteractive(getAccountByPassword, getAccountByChallengeResponse, cfg)
 }
 
 func TestUserInteractiveChallenge(t *testing.T) {

clientapi/httputil/httputil.go

@@ -15,7 +15,9 @@
 package httputil
 
 import (
+	"bytes"
 	"encoding/json"
+	"github.com/matrix-org/dendrite/clientapi/auth"
 	"io/ioutil"
 	"net/http"
 	"unicode/utf8"
@@ -54,3 +56,19 @@ func UnmarshalJSONRequest(req *http.Request, iface interface{}) *util.JSONRespon
 	}
 	return nil
 }
+
+func GetLoginType(req *http.Request) (string, *util.JSONResponse) {
+	body, err := ioutil.ReadAll(req.Body)
+	if err != nil {
+		resp := jsonerror.InternalServerError()
+		return "", &resp
+	}
+	req.Body = ioutil.NopCloser(bytes.NewReader(body))
+	r := &auth.Login{}
+	jsonErr := UnmarshalJSONRequest(req, r)
+	if jsonErr != nil {
+		return "", jsonErr
+	}
+	req.Body = ioutil.NopCloser(bytes.NewReader(body))
+	return r.Type, nil
+}

clientapi/routing/key_crosssigning.go

@@ -67,7 +67,7 @@ func UploadCrossSigningDeviceKeys(
 		GetAccountByPassword: accountDB.GetAccountByPassword,
 		Config:               cfg,
 	}
-	if _, authErr := typePassword.Login(req.Context(), &uploadReq.Auth.PasswordRequest); authErr != nil {
+	if _, authErr := typePassword.Login(req.Context(), &uploadReq.Auth.PasswordRequest, ""); authErr != nil {
 		return *authErr
 	}
 	AddCompletedSessionStage(sessionID, authtypes.LoginTypePassword)

clientapi/routing/login.go

@@ -16,6 +16,9 @@ package routing
 
 import (
 	"context"
+	"fmt"
+	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
+	"io/ioutil"
 	"net/http"
 
 	"github.com/matrix-org/dendrite/clientapi/auth"
@@ -44,27 +47,34 @@ type flow struct {
 	Type string `json:"type"`
 }
 
-func passwordLogin() flows {
+func enabledLoginTypes(cfg *config.ClientAPI) flows {
 	f := flows{}
+	for _, loginType := range cfg.LoginTypes {
 		s := flow{
-		Type: "m.login.password",
+			Type: loginType,
 		}
 		f.Flows = append(f.Flows, s)
+	}
 	return f
 }
 
 // Login implements GET and POST /login
 func Login(
 	req *http.Request, accountDB accounts.Database, userAPI userapi.UserInternalAPI,
-	cfg *config.ClientAPI,
+	cfg *config.ClientAPI, userInteractiveAuth *auth.UserInteractive,
 ) util.JSONResponse {
 	if req.Method == http.MethodGet {
-		// TODO: support other forms of login other than password, depending on config options
 		return util.JSONResponse{
 			Code: http.StatusOK,
-			JSON: passwordLogin(),
+			JSON: enabledLoginTypes(cfg),
 		}
 	} else if req.Method == http.MethodPost {
+		loginType, err := httputil.GetLoginType(req)
+		if err != nil {
+			return *err
+		}
+		switch loginType {
+		case authtypes.LoginTypePassword:
 			typePassword := auth.LoginTypePassword{
 				GetAccountByPassword: accountDB.GetAccountByPassword,
 				Config:               cfg,
@@ -74,12 +84,33 @@ func Login(
 			if resErr != nil {
 				return *resErr
 			}
-		login, authErr := typePassword.Login(req.Context(), r)
+			login, authErr := typePassword.Login(req.Context(), r, "")
 			if authErr != nil {
 				return *authErr
 			}
 			// make a device/access token
 			return completeAuth(req.Context(), cfg.Matrix.ServerName, userAPI, login, req.RemoteAddr, req.UserAgent())
+		case authtypes.LoginTypeChallengeResponse:
+			defer req.Body.Close() // nolint:errcheck
+			bodyBytes, err := ioutil.ReadAll(req.Body)
+			if err != nil {
+				return util.JSONResponse{
+					Code: http.StatusBadRequest,
+					JSON: jsonerror.BadJSON("The request body could not be read: " + err.Error()),
+				}
+			}
+			login, resErr := userInteractiveAuth.Verify(req.Context(), bodyBytes, nil)
+			if resErr != nil {
+				return *resErr
+			}
+			// create a device/access token
+			return completeAuth(req.Context(), cfg.Matrix.ServerName, userAPI, login, req.RemoteAddr, req.UserAgent())
+		default:
+			return util.JSONResponse{
+				Code: http.StatusBadRequest,
+				JSON: jsonerror.InvalidParam(fmt.Sprintf("Unsupported login type: %s", loginType)),
+			}
+		}
 	}
 	return util.JSONResponse{
 		Code: http.StatusMethodNotAllowed,

clientapi/routing/password.go

@@ -71,7 +71,7 @@ func Password(
 		GetAccountByPassword: accountDB.GetAccountByPassword,
 		Config:               cfg,
 	}
-	if _, authErr := typePassword.Login(req.Context(), &r.Auth.PasswordRequest); authErr != nil {
+	if _, authErr := typePassword.Login(req.Context(), &r.Auth.PasswordRequest, ""); authErr != nil {
 		return *authErr
 	}
 	AddCompletedSessionStage(sessionID, authtypes.LoginTypePassword)

clientapi/routing/register.go

@@ -123,6 +123,7 @@ type registerRequest struct {
 	// registration parameters
 	Password            string `json:"password"`
 	Username            string `json:"username"`
+	B64encodedPublicKey string `json:"b64PublicKey"`
 	Admin               bool   `json:"admin"`
 	// user-interactive auth params
 	Auth authDict `json:"auth"`
@@ -518,6 +519,7 @@ func Register(
 	logger := util.GetLogger(req.Context())
 	logger.WithFields(log.Fields{
 		"username":     r.Username,
+		"b64PublicKey": r.B64encodedPublicKey,
 		"auth.type":    r.Auth.Type,
 		"session_id":   r.Auth.Session,
 	}).Info("Processing registration request")
@@ -700,7 +702,7 @@ func handleApplicationServiceRegistration(
 	// Don't need to worry about appending to registration stages as
 	// application service registration is entirely separate.
 	return completeRegistration(
-		req.Context(), userAPI, r.Username, "", appserviceID, req.RemoteAddr, req.UserAgent(),
+		req.Context(), userAPI, r.Username, "", "", appserviceID, req.RemoteAddr, req.UserAgent(),
 		r.InhibitLogin, r.InitialDisplayName, r.DeviceID,
 	)
 }
@@ -719,7 +721,7 @@ func checkAndCompleteFlow(
 	if checkFlowCompleted(flow, cfg.Derived.Registration.Flows) {
 		// This flow was completed, registration can continue
 		return completeRegistration(
-			req.Context(), userAPI, r.Username, r.Password, "", req.RemoteAddr, req.UserAgent(),
+			req.Context(), userAPI, r.Username, r.Password, r.B64encodedPublicKey, "", req.RemoteAddr, req.UserAgent(),
 			r.InhibitLogin, r.InitialDisplayName, r.DeviceID,
 		)
 	}
@@ -739,13 +741,7 @@ func checkAndCompleteFlow(
 // registerRequest, as this function serves requests encoded as both
 // registerRequests and legacyRegisterRequests, which share some attributes but
 // not all
-func completeRegistration(
+func completeRegistration(ctx context.Context, userAPI userapi.UserInternalAPI, username, password, b64encodedPublicKey, appserviceID, ipAddr, userAgent string, inhibitLogin eventutil.WeakBoolean, displayName, deviceID *string) util.JSONResponse {
-	ctx context.Context,
-	userAPI userapi.UserInternalAPI,
-	username, password, appserviceID, ipAddr, userAgent string,
-	inhibitLogin eventutil.WeakBoolean,
-	displayName, deviceID *string,
-) util.JSONResponse {
 	if username == "" {
 		return util.JSONResponse{
 			Code: http.StatusBadRequest,
@@ -765,6 +761,7 @@ func completeRegistration(
 		AppServiceID:        appserviceID,
 		Localpart:           username,
 		Password:            password,
+		B64encodedPublicKey: b64encodedPublicKey,
 		AccountType:         userapi.AccountTypeUser,
 		OnConflict:          userapi.ConflictAbort,
 	}, &accRes)
@@ -963,5 +960,5 @@ func handleSharedSecretRegistration(userAPI userapi.UserInternalAPI, sr *SharedS
 		return *resErr
 	}
 	deviceID := "shared_secret_registration"
-	return completeRegistration(req.Context(), userAPI, ssrr.User, ssrr.Password, "", req.RemoteAddr, req.UserAgent(), false, &ssrr.User, &deviceID)
+	return completeRegistration(req.Context(), userAPI, ssrr.User, ssrr.Password, "", "", req.RemoteAddr, req.UserAgent(), false, &ssrr.User, &deviceID)
 }

clientapi/routing/routing.go

@@ -62,7 +62,7 @@ func Setup(
 	mscCfg *config.MSCs,
 ) {
 	rateLimits := httputil.NewRateLimits(&cfg.RateLimiting)
-	userInteractiveAuth := auth.NewUserInteractive(accountDB.GetAccountByPassword, cfg)
+	userInteractiveAuth := auth.NewUserInteractive(accountDB.GetAccountByPassword, accountDB.GetAccountByChallengeResponse, cfg)
 
 	unstableFeatures := map[string]bool{
 		"org.matrix.e2e_cross_signing": true,
@@ -498,7 +498,7 @@ func Setup(
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
 			}
-			return Login(req, accountDB, userAPI, cfg)
+			return Login(req, accountDB, userAPI, cfg, userInteractiveAuth)
 		}),
 	).Methods(http.MethodGet, http.MethodPost, http.MethodOptions)
 

cmd/create-account/main.go

@@ -16,6 +16,9 @@ package main
 
 import (
 	"context"
+	"crypto/ed25519"
+	"crypto/rand"
+	"encoding/base64"
 	"flag"
 	"fmt"
 	"io"
@@ -39,6 +42,8 @@ Example:
 
 	# provide password by parameter
   	%s --config dendrite.yaml -username alice -password foobarbaz
+	# auto generate keypair
+  	%s --config dendrite.yaml -username alice -password foobarbaz -udk NuJ7J4BsaE8QZT1ULNTc3s8ZjLFmDPh91l1i0Urf/ls=
 	# use password from file
   	%s --config dendrite.yaml -username alice -passwordfile my.pass
 	# ask user to provide password
@@ -54,6 +59,7 @@ Arguments:
 var (
 	username      = flag.String("username", "", "The username of the account to register (specify the localpart only, e.g. 'alice' for '@alice:domain.com')")
 	password      = flag.String("password", "", "The password to associate with the account (optional, account will be password-less if not specified)")
+	createKeypair = flag.Bool("create-keypair", false, "Whether to create an Ed25519 keypair for the account to create (optional)")
 	pwdFile       = flag.String("passwordfile", "", "The file to use for the password (e.g. for automated account creation)")
 	pwdStdin      = flag.Bool("passwordstdin", false, "Reads the password from stdin")
 	askPass       = flag.Bool("ask-pass", false, "Ask for the password to use")
@@ -62,7 +68,7 @@ var (
 func main() {
 	name := os.Args[0]
 	flag.Usage = func() {
-		_, _ = fmt.Fprintf(os.Stderr, usage, name, name, name, name, name, name)
+		_, _ = fmt.Fprintf(os.Stderr, usage, name, name, name, name, name, name, name)
 		flag.PrintDefaults()
 	}
 	cfg := setup.ParseFlags(true)
@@ -81,7 +87,32 @@ func main() {
 		logrus.Fatalln("Failed to connect to the database:", err.Error())
 	}
 
-	_, err = accountDB.CreateAccount(context.Background(), *username, pass, "")
+	var pub64 string
+	if *createKeypair {
+		pub, priv, err2 := ed25519.GenerateKey(rand.Reader)
+		pub64 = base64.StdEncoding.EncodeToString(priv.Public().(ed25519.PublicKey))
+		if err2 != nil {
+			logrus.Fatalln(err2)
+		}
+		err2 = os.WriteFile("private.key", priv, 0644)
+		if err2 != nil {
+			logrus.Fatalln(err2)
+		}
+		err2 = os.WriteFile("private.key.seed", priv.Seed(), 0644)
+		if err2 != nil {
+			logrus.Fatalln(err2)
+		}
+		err2 = os.WriteFile("./public.key", pub, 0644)
+		if err2 != nil {
+			logrus.Fatalln(err2)
+		}
+		err2 = os.WriteFile("./public.key.b64", []byte(pub64), 0644)
+		if err2 != nil {
+			logrus.Fatalln(err2)
+		}
+	}
+
+	_, err = accountDB.CreateAccount(context.Background(), *username, pass, pub64, "")
 	if err != nil {
 		logrus.Fatalln("Failed to create the account:", err.Error())
 	}

cmd/sign-challenge/main.go

@@ -0,0 +1,61 @@
+// Copyright 2017 Vector Creations Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"crypto/ed25519"
+	"encoding/base64"
+	"flag"
+	"fmt"
+	"github.com/sirupsen/logrus"
+	"os"
+)
+
+const usage = `Usage: %s
+
+Sign a string using an Ed25519 private key
+
+Arguments:
+
+`
+
+var (
+	privateKeyFile = flag.String("private-key", "", "An Ed25519 private key seed used to sign the input")
+	input          = flag.String("input", "", "The input to sign")
+)
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, usage, os.Args[0])
+		flag.PrintDefaults()
+	}
+
+	flag.Parse()
+
+	if *privateKeyFile == "" || *input == "" {
+		flag.Usage()
+		return
+	}
+
+	if *privateKeyFile != "" && *input != "" {
+		seedBytes, err := os.ReadFile(*privateKeyFile)
+		if err != nil {
+			logrus.Fatalln(err)
+		}
+		priv := ed25519.NewKeyFromSeed(seedBytes)
+		sig := ed25519.Sign(priv, []byte(*input))
+		logrus.Infoln("Signature: " + base64.StdEncoding.EncodeToString(sig))
+	}
+}

dendrite-config.yaml

@@ -145,6 +145,11 @@ client_api:
   external_api:
     listen: http://[::]:8071
 
+  # Which of the authentication flows to support on this server
+  login_types:
+    - m.login.password
+    - m.login.challenge_response
+
   # Prevents new users from being able to register on this homeserver, except when
   # using the registration shared secret below.
   registration_disabled: false

setup/config/config_clientapi.go

@@ -12,6 +12,10 @@ type ClientAPI struct {
 	InternalAPI InternalAPIOptions `yaml:"internal_api"`
 	ExternalAPI ExternalAPIOptions `yaml:"external_api"`
 
+	// What authentication mechanisms shall be supported
+	// by this server
+	LoginTypes []string `yaml:"login_types"`
+
 	// If set disables new users from registering (except via shared
 	// secrets)
 	RegistrationDisabled bool `yaml:"registration_disabled"`
@@ -45,6 +49,7 @@ func (c *ClientAPI) Defaults(generate bool) {
 	c.InternalAPI.Listen = "http://localhost:7771"
 	c.InternalAPI.Connect = "http://localhost:7771"
 	c.ExternalAPI.Listen = "http://[::]:8071"
+	c.LoginTypes = []string{"m.login.password"}
 	c.RegistrationSharedSecret = ""
 	c.RecaptchaPublicKey = ""
 	c.RecaptchaPrivateKey = ""

userapi/api/api.go

@@ -245,6 +245,7 @@ type PerformAccountCreationRequest struct {
 
 	AppServiceID        string // optional: the application service ID (not user ID) creating this account, if any.
 	Password            string // optional: if missing then this account will be a passwordless account
+	B64encodedPublicKey string // optional: if missing then this account will not allow digital signature login until a public key is added
 	OnConflict          Conflict
 }
 

userapi/internal/api.go

@@ -67,7 +67,7 @@ func (a *UserInternalAPI) PerformAccountCreation(ctx context.Context, req *api.P
 		res.Account = acc
 		return nil
 	}
-	acc, err := a.AccountDB.CreateAccount(ctx, req.Localpart, req.Password, req.AppServiceID)
+	acc, err := a.AccountDB.CreateAccount(ctx, req.Localpart, req.Password, req.B64encodedPublicKey, req.AppServiceID)
 	if err != nil {
 		if errors.Is(err, sqlutil.ErrUserExists) { // This account already exists
 			switch req.OnConflict {

userapi/storage/accounts/interface.go

@@ -27,6 +27,7 @@ import (
 type Database interface {
 	internal.PartitionStorer
 	GetAccountByPassword(ctx context.Context, localpart, plaintextPassword string) (*api.Account, error)
+	GetAccountByChallengeResponse(ctx context.Context, localpart, b64encodedSignature, challenge string) (*api.Account, error)
 	GetProfileByLocalpart(ctx context.Context, localpart string) (*authtypes.Profile, error)
 	SetPassword(ctx context.Context, localpart string, plaintextPassword string) error
 	SetAvatarURL(ctx context.Context, localpart string, avatarURL string) error
@@ -34,7 +35,7 @@ type Database interface {
 	// CreateAccount makes a new account with the given login name and password, and creates an empty profile
 	// for this account. If no password is supplied, the account will be a passwordless account. If the
 	// account already exists, it will return nil, ErrUserExists.
-	CreateAccount(ctx context.Context, localpart, plaintextPassword, appserviceID string) (*api.Account, error)
+	CreateAccount(ctx context.Context, localpart, plaintextPassword, b64encodedPublicKey, appserviceID string) (*api.Account, error)
 	CreateGuestAccount(ctx context.Context) (*api.Account, error)
 	SaveAccountData(ctx context.Context, localpart, roomID, dataType string, content json.RawMessage) error
 	GetAccountData(ctx context.Context, localpart string) (global map[string]json.RawMessage, rooms map[string]map[string]json.RawMessage, err error)

userapi/storage/accounts/postgres/accounts_table.go

@@ -36,6 +36,8 @@ CREATE TABLE IF NOT EXISTS account_accounts (
     created_ts BIGINT NOT NULL,
     -- The password hash for this account. Can be NULL if this is a passwordless account.
     password_hash TEXT,
+    -- The public key for this account, base64 encoded.
+    b64_public_key TEXT,
     -- Identifies which application service this account belongs to, if any.
     appservice_id TEXT,
     -- If the account is currently active
@@ -48,7 +50,7 @@ CREATE SEQUENCE IF NOT EXISTS numeric_username_seq START 1;
 `
 
 const insertAccountSQL = "" +
-	"INSERT INTO account_accounts(localpart, created_ts, password_hash, appservice_id) VALUES ($1, $2, $3, $4)"
+	"INSERT INTO account_accounts(localpart, created_ts, password_hash, b64_public_key, appservice_id) VALUES ($1, $2, $3, $4)"
 
 const updatePasswordSQL = "" +
 	"UPDATE account_accounts SET password_hash = $1 WHERE localpart = $2"
@@ -62,6 +64,9 @@ const selectAccountByLocalpartSQL = "" +
 const selectPasswordHashSQL = "" +
 	"SELECT password_hash FROM account_accounts WHERE localpart = $1 AND is_deactivated = FALSE"
 
+const selectb64PubKeySQL = "" +
+	"SELECT b64_public_key FROM account_accounts WHERE localpart = $1 AND is_deactivated = 0"
+
 const selectNewNumericLocalpartSQL = "" +
 	"SELECT nextval('numeric_username_seq')"
 
@@ -71,6 +76,7 @@ type accountsStatements struct {
 	deactivateAccountStmt         *sql.Stmt
 	selectAccountByLocalpartStmt  *sql.Stmt
 	selectPasswordHashStmt        *sql.Stmt
+	selectb64PubKeyStmt           *sql.Stmt
 	selectNewNumericLocalpartStmt *sql.Stmt
 	serverName                    gomatrixserverlib.ServerName
 }
@@ -88,6 +94,7 @@ func (s *accountsStatements) prepare(db *sql.DB, server gomatrixserverlib.Server
 		{&s.deactivateAccountStmt, deactivateAccountSQL},
 		{&s.selectAccountByLocalpartStmt, selectAccountByLocalpartSQL},
 		{&s.selectPasswordHashStmt, selectPasswordHashSQL},
+		{&s.selectb64PubKeyStmt, selectb64PubKeySQL},
 		{&s.selectNewNumericLocalpartStmt, selectNewNumericLocalpartSQL},
 	}.Prepare(db)
 }
@@ -95,17 +102,15 @@ func (s *accountsStatements) prepare(db *sql.DB, server gomatrixserverlib.Server
 // insertAccount creates a new account. 'hash' should be the password hash for this account. If it is missing,
 // this account will be passwordless. Returns an error if this account already exists. Returns the account
 // on success.
-func (s *accountsStatements) insertAccount(
+func (s *accountsStatements) insertAccount(ctx context.Context, txn *sql.Tx, localpart, hash, b64PubKey, appserviceID string) (*api.Account, error) {
-	ctx context.Context, txn *sql.Tx, localpart, hash, appserviceID string,
-) (*api.Account, error) {
 	createdTimeMS := time.Now().UnixNano() / 1000000
 	stmt := sqlutil.TxStmt(txn, s.insertAccountStmt)
 
 	var err error
 	if appserviceID == "" {
-		_, err = stmt.ExecContext(ctx, localpart, createdTimeMS, hash, nil)
+		_, err = stmt.ExecContext(ctx, localpart, createdTimeMS, hash, b64PubKey, nil)
 	} else {
-		_, err = stmt.ExecContext(ctx, localpart, createdTimeMS, hash, appserviceID)
+		_, err = stmt.ExecContext(ctx, localpart, createdTimeMS, hash, nil, appserviceID)
 	}
 	if err != nil {
 		return nil, err
@@ -140,6 +145,13 @@ func (s *accountsStatements) selectPasswordHash(
 	return
 }
 
+func (s *accountsStatements) selectb64PubKey(
+	ctx context.Context, localpart string,
+) (b64PubKey string, err error) {
+	err = s.selectb64PubKeyStmt.QueryRowContext(ctx, localpart).Scan(&b64PubKey)
+	return
+}
+
 func (s *accountsStatements) selectAccountByLocalpart(
 	ctx context.Context, localpart string,
 ) (*api.Account, error) {

userapi/storage/accounts/postgres/storage.go

@@ -16,7 +16,9 @@ package postgres
 
 import (
 	"context"
+	"crypto/ed25519"
 	"database/sql"
+	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -120,6 +122,29 @@ func (d *Database) GetAccountByPassword(
 	return d.accounts.selectAccountByLocalpart(ctx, localpart)
 }
 
+// GetAccountByChallengeResponse returns the account associated with the given localpart and public key
+// if the given signature can be traced back to the public key.
+// Returns sql.ErrNoRows if no account exists which matches the given localpart.
+func (d *Database) GetAccountByChallengeResponse(ctx context.Context, localpart, b64encodedSignature, challenge string) (*api.Account, error) {
+	b64PubKey, err := d.accounts.selectb64PubKey(ctx, localpart)
+	if err != nil {
+		return nil, err
+	}
+	pubKey, err := base64.StdEncoding.DecodeString(b64PubKey)
+	if err != nil {
+		return nil, err
+	}
+	sig, err := base64.StdEncoding.DecodeString(b64encodedSignature)
+	if err != nil {
+		return nil, err
+	}
+	verified := ed25519.Verify(pubKey, []byte(challenge), sig)
+	if !verified {
+		return nil, errors.New("Authentication error: Invalid signature")
+	}
+	return d.accounts.selectAccountByLocalpart(ctx, localpart)
+}
+
 // GetProfileByLocalpart returns the profile associated with the given localpart.
 // Returns sql.ErrNoRows if no profile exists which matches the given localpart.
 func (d *Database) GetProfileByLocalpart(
@@ -165,7 +190,7 @@ func (d *Database) CreateGuestAccount(ctx context.Context) (acc *api.Account, er
 			return err
 		}
 		localpart := strconv.FormatInt(numLocalpart, 10)
-		acc, err = d.createAccount(ctx, txn, localpart, "", "")
+		acc, err = d.createAccount(ctx, txn, localpart, "", "", "")
 		return err
 	})
 	return acc, err
@@ -174,19 +199,15 @@ func (d *Database) CreateGuestAccount(ctx context.Context) (acc *api.Account, er
 // CreateAccount makes a new account with the given login name and password, and creates an empty profile
 // for this account. If no password is supplied, the account will be a passwordless account. If the
 // account already exists, it will return nil, sqlutil.ErrUserExists.
-func (d *Database) CreateAccount(
+func (d *Database) CreateAccount(ctx context.Context, localpart, plaintextPassword, b64encodedPublicKey, appserviceID string) (acc *api.Account, err error) {
-	ctx context.Context, localpart, plaintextPassword, appserviceID string,
-) (acc *api.Account, err error) {
 	err = sqlutil.WithTransaction(d.db, func(txn *sql.Tx) error {
-		acc, err = d.createAccount(ctx, txn, localpart, plaintextPassword, appserviceID)
+		acc, err = d.createAccount(ctx, txn, localpart, plaintextPassword, b64encodedPublicKey, appserviceID)
 		return err
 	})
 	return
 }
 
-func (d *Database) createAccount(
+func (d *Database) createAccount(ctx context.Context, txn *sql.Tx, localpart, plaintextPassword, publicKey, appserviceID string) (*api.Account, error) {
-	ctx context.Context, txn *sql.Tx, localpart, plaintextPassword, appserviceID string,
-) (*api.Account, error) {
 	var account *api.Account
 	var err error
 	// Generate a password hash if this is not a password-less user
@@ -197,7 +218,7 @@ func (d *Database) createAccount(
 			return nil, err
 		}
 	}
-	if account, err = d.accounts.insertAccount(ctx, txn, localpart, hash, appserviceID); err != nil {
+	if account, err = d.accounts.insertAccount(ctx, txn, localpart, hash, publicKey, appserviceID); err != nil {
 		if sqlutil.IsUniqueConstraintViolationErr(err) {
 			return nil, sqlutil.ErrUserExists
 		}

userapi/storage/accounts/sqlite3/accounts_table.go

@@ -36,6 +36,8 @@ CREATE TABLE IF NOT EXISTS account_accounts (
     created_ts BIGINT NOT NULL,
     -- The password hash for this account. Can be NULL if this is a passwordless account.
     password_hash TEXT,
+    -- The public key for this account, base64 encoded.
+    b64_public_key TEXT,
     -- Identifies which application service this account belongs to, if any.
     appservice_id TEXT,
     -- If the account is currently active
@@ -46,7 +48,7 @@ CREATE TABLE IF NOT EXISTS account_accounts (
 `
 
 const insertAccountSQL = "" +
-	"INSERT INTO account_accounts(localpart, created_ts, password_hash, appservice_id) VALUES ($1, $2, $3, $4)"
+	"INSERT INTO account_accounts(localpart, created_ts, password_hash, b64_public_key, appservice_id) VALUES ($1, $2, $3, $4, $5)"
 
 const updatePasswordSQL = "" +
 	"UPDATE account_accounts SET password_hash = $1 WHERE localpart = $2"
@@ -60,6 +62,9 @@ const selectAccountByLocalpartSQL = "" +
 const selectPasswordHashSQL = "" +
 	"SELECT password_hash FROM account_accounts WHERE localpart = $1 AND is_deactivated = 0"
 
+const selectb64PubKeySQL = "" +
+	"SELECT b64_public_key FROM account_accounts WHERE localpart = $1 AND is_deactivated = 0"
+
 const selectNewNumericLocalpartSQL = "" +
 	"SELECT COUNT(localpart) FROM account_accounts"
 
@@ -70,6 +75,7 @@ type accountsStatements struct {
 	deactivateAccountStmt         *sql.Stmt
 	selectAccountByLocalpartStmt  *sql.Stmt
 	selectPasswordHashStmt        *sql.Stmt
+	selectb64PubKeyStmt           *sql.Stmt
 	selectNewNumericLocalpartStmt *sql.Stmt
 	serverName                    gomatrixserverlib.ServerName
 }
@@ -88,6 +94,7 @@ func (s *accountsStatements) prepare(db *sql.DB, server gomatrixserverlib.Server
 		{&s.deactivateAccountStmt, deactivateAccountSQL},
 		{&s.selectAccountByLocalpartStmt, selectAccountByLocalpartSQL},
 		{&s.selectPasswordHashStmt, selectPasswordHashSQL},
+		{&s.selectb64PubKeyStmt, selectb64PubKeySQL},
 		{&s.selectNewNumericLocalpartStmt, selectNewNumericLocalpartSQL},
 	}.Prepare(db)
 }
@@ -95,17 +102,15 @@ func (s *accountsStatements) prepare(db *sql.DB, server gomatrixserverlib.Server
 // insertAccount creates a new account. 'hash' should be the password hash for this account. If it is missing,
 // this account will be passwordless. Returns an error if this account already exists. Returns the account
 // on success.
-func (s *accountsStatements) insertAccount(
+func (s *accountsStatements) insertAccount(ctx context.Context, txn *sql.Tx, localpart, hash, b64PubKey, appserviceID string) (*api.Account, error) {
-	ctx context.Context, txn *sql.Tx, localpart, hash, appserviceID string,
-) (*api.Account, error) {
 	createdTimeMS := time.Now().UnixNano() / 1000000
 	stmt := s.insertAccountStmt
 
 	var err error
 	if appserviceID == "" {
-		_, err = sqlutil.TxStmt(txn, stmt).ExecContext(ctx, localpart, createdTimeMS, hash, nil)
+		_, err = sqlutil.TxStmt(txn, stmt).ExecContext(ctx, localpart, createdTimeMS, hash, b64PubKey, nil)
 	} else {
-		_, err = sqlutil.TxStmt(txn, stmt).ExecContext(ctx, localpart, createdTimeMS, hash, appserviceID)
+		_, err = sqlutil.TxStmt(txn, stmt).ExecContext(ctx, localpart, createdTimeMS, hash, nil, appserviceID)
 	}
 	if err != nil {
 		return nil, err
@@ -140,6 +145,13 @@ func (s *accountsStatements) selectPasswordHash(
 	return
 }
 
+func (s *accountsStatements) selectb64PubKey(
+	ctx context.Context, localpart string,
+) (b64PubKey string, err error) {
+	err = s.selectb64PubKeyStmt.QueryRowContext(ctx, localpart).Scan(&b64PubKey)
+	return
+}
+
 func (s *accountsStatements) selectAccountByLocalpart(
 	ctx context.Context, localpart string,
 ) (*api.Account, error) {

userapi/storage/accounts/sqlite3/deltas/20200929203058_is_active.go

@@ -23,6 +23,7 @@ CREATE TABLE account_accounts (
     localpart TEXT NOT NULL PRIMARY KEY,
     created_ts BIGINT NOT NULL,
     password_hash TEXT,
+    b64_public_key TEXT,
     appservice_id TEXT,
     is_deactivated BOOLEAN DEFAULT 0
 );
@@ -47,6 +48,7 @@ CREATE TABLE account_accounts (
     localpart TEXT NOT NULL PRIMARY KEY,
     created_ts BIGINT NOT NULL,
     password_hash TEXT,
+    b64_public_key TEXT,
     appservice_id TEXT
 );
 INSERT

userapi/storage/accounts/sqlite3/storage.go

@@ -16,7 +16,9 @@ package sqlite3
 
 import (
 	"context"
+	"crypto/ed25519"
 	"database/sql"
+	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -125,6 +127,29 @@ func (d *Database) GetAccountByPassword(
 	return d.accounts.selectAccountByLocalpart(ctx, localpart)
 }
 
+// GetAccountByChallengeResponse returns the account associated with the given localpart and public key
+// if the given signature can be traced back to the public key.
+// Returns sql.ErrNoRows if no account exists which matches the given localpart.
+func (d *Database) GetAccountByChallengeResponse(ctx context.Context, localpart, b64encodedSignature, challenge string) (*api.Account, error) {
+	b64PubKey, err := d.accounts.selectb64PubKey(ctx, localpart)
+	if err != nil {
+		return nil, err
+	}
+	pubKey, err := base64.StdEncoding.DecodeString(b64PubKey)
+	if err != nil {
+		return nil, err
+	}
+	sig, err := base64.StdEncoding.DecodeString(b64encodedSignature)
+	if err != nil {
+		return nil, err
+	}
+	verified := ed25519.Verify(pubKey, []byte(challenge), sig)
+	if !verified {
+		return nil, errors.New("Authentication error: Invalid signature")
+	}
+	return d.accounts.selectAccountByLocalpart(ctx, localpart)
+}
+
 // GetProfileByLocalpart returns the profile associated with the given localpart.
 // Returns sql.ErrNoRows if no profile exists which matches the given localpart.
 func (d *Database) GetProfileByLocalpart(
@@ -191,7 +216,7 @@ func (d *Database) CreateGuestAccount(ctx context.Context) (acc *api.Account, er
 			return err
 		}
 		localpart := strconv.FormatInt(numLocalpart, 10)
-		acc, err = d.createAccount(ctx, txn, localpart, "", "")
+		acc, err = d.createAccount(ctx, txn, localpart, "", "", "")
 		return err
 	})
 	return acc, err
@@ -200,9 +225,7 @@ func (d *Database) CreateGuestAccount(ctx context.Context) (acc *api.Account, er
 // CreateAccount makes a new account with the given login name and password, and creates an empty profile
 // for this account. If no password is supplied, the account will be a passwordless account. If the
 // account already exists, it will return nil, ErrUserExists.
-func (d *Database) CreateAccount(
+func (d *Database) CreateAccount(ctx context.Context, localpart, plaintextPassword, b64encodedPublicKey, appserviceID string) (acc *api.Account, err error) {
-	ctx context.Context, localpart, plaintextPassword, appserviceID string,
-) (acc *api.Account, err error) {
 	// Create one account at a time else we can get 'database is locked'.
 	d.profilesMu.Lock()
 	d.accountDatasMu.Lock()
@@ -211,7 +234,7 @@ func (d *Database) CreateAccount(
 	defer d.accountDatasMu.Unlock()
 	defer d.accountsMu.Unlock()
 	err = d.writer.Do(d.db, nil, func(txn *sql.Tx) error {
-		acc, err = d.createAccount(ctx, txn, localpart, plaintextPassword, appserviceID)
+		acc, err = d.createAccount(ctx, txn, localpart, plaintextPassword, b64encodedPublicKey, appserviceID)
 		return err
 	})
 	return
@@ -219,9 +242,7 @@ func (d *Database) CreateAccount(
 
 // WARNING! This function assumes that the relevant mutexes have already
 // been taken out by the caller (e.g. CreateAccount or CreateGuestAccount).
-func (d *Database) createAccount(
+func (d *Database) createAccount(ctx context.Context, txn *sql.Tx, localpart, plaintextPassword, publicKey, appserviceID string) (*api.Account, error) {
-	ctx context.Context, txn *sql.Tx, localpart, plaintextPassword, appserviceID string,
-) (*api.Account, error) {
 	var err error
 	var account *api.Account
 	// Generate a password hash if this is not a password-less user
@@ -232,7 +253,7 @@ func (d *Database) createAccount(
 			return nil, err
 		}
 	}
-	if account, err = d.accounts.insertAccount(ctx, txn, localpart, hash, appserviceID); err != nil {
+	if account, err = d.accounts.insertAccount(ctx, txn, localpart, hash, publicKey, appserviceID); err != nil {
 		return nil, sqlutil.ErrUserExists
 	}
 	if err = d.profiles.insertProfile(ctx, txn, localpart); err != nil {

userapi/userapi_test.go

@@ -48,7 +48,7 @@ func TestQueryProfile(t *testing.T) {
 	aliceAvatarURL := "mxc://example.com/alice"
 	aliceDisplayName := "Alice"
 	userAPI, accountDB := MustMakeInternalAPI(t)
-	_, err := accountDB.CreateAccount(context.TODO(), "alice", "foobar", "")
+	_, err := accountDB.CreateAccount(context.TODO(), "alice", "foobar", "", "")
 	if err != nil {
 		t.Fatalf("failed to make account: %s", err)
 	}