Improved signature handling & instance actor (#8275)

This PR is part of https://codeberg.org/forgejo/forgejo/pulls/4767

It improves the signature handling:
1. move logic to a service (might be used from other services as well)
2. make a clear difference between ` ReqHTTPUserSignature` and `ReqHTTPUserOrInstanceSignature`
3. improve test ability (activitypub/client & distant_federation_server_mock

Adjust instance actor
1. name &
2. webfinger

## Strategy for next PRs is

Integration tests are in the driving seat.

I will step by step add integration tests form original PR and add code required by the integration test changes.

## Meta

Proposal howto process large PRs can be discussed here: https://codeberg.org/forgejo-contrib/federation/pulls/37

Current state with rendered diagrams can be found here: https://codeberg.org/meissa/federation/src/branch/merge-large-pr/doc/merge-large-pr.md

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8275
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Michael Jerger <michael.jerger@meissa-gmbh.de>
Co-committed-by: Michael Jerger <michael.jerger@meissa-gmbh.de>

.deadcode-out

@@ -34,9 +34,6 @@ forgejo.org/models/dbfs
 	Create
 	Rename
 
-forgejo.org/models/forgefed
-	GetFederationHost
-
 forgejo.org/models/forgejo/semver
 	GetVersion
 	SetVersionString
@@ -68,7 +65,6 @@ forgejo.org/models/user
 	DeleteUserSetting
 	GetFederatedUser
 	GetFederatedUserByUserID
-	UpdateFederatedUser
 	GetFollowersForUser
 	AddFollower
 	RemoveFollower
@@ -249,6 +245,9 @@ forgejo.org/routers/web/org
 forgejo.org/services/context
 	GetPrivateContext
 
+forgejo.org/services/federation
+	Init
+
 forgejo.org/services/repository
 	IsErrForkAlreadyExist
 

models/user/activitypub.go

@@ -19,7 +19,7 @@ func (u *User) APActorID() string {
 	return fmt.Sprintf("%sapi/v1/activitypub/user-id/%s", setting.AppURL, url.PathEscape(fmt.Sprintf("%d", u.ID)))
 }
 
-// APActorKeyID returns the ID of the user's public key
-func (u *User) APActorKeyID() string {
+// KeyID returns the ID of the user's public key
+func (u *User) KeyID() string {
 	return u.APActorID() + "#main-key"
 }

models/user/user_repository.go

@@ -57,14 +57,6 @@ func CreateFederatedUser(ctx context.Context, user *User, federatedUser *Federat
 	return committer.Commit()
 }
 
-func (federatedUser *FederatedUser) UpdateFederatedUser(ctx context.Context) error {
-	if _, err := validation.IsValid(federatedUser); err != nil {
-		return err
-	}
-	_, err := db.GetEngine(ctx).ID(federatedUser.ID).Cols("inbox_path").Update(federatedUser)
-	return err
-}
-
 func FindFederatedUser(ctx context.Context, externalID string, federationHostID int64) (*User, *FederatedUser, error) {
 	federatedUser := new(FederatedUser)
 	user := new(User)
@@ -219,7 +211,6 @@ func RemoveFollower(ctx context.Context, followedUser *User, followingUser *Fede
 	return err
 }
 
-// TODO: We should unify Activity-pub-following and classical following (see models/user/follow.go)
 func IsFollowingAp(ctx context.Context, followedUser *User, followingUser *FederatedUser) (bool, error) {
 	if res, err := validation.IsValid(followedUser); !res {
 		return false, err

models/user/user_test.go

@@ -150,7 +150,7 @@ func TestAPActorID_APActorID(t *testing.T) {
 
 func TestKeyID(t *testing.T) {
 	user := user_model.User{ID: 1}
-	url := user.APActorKeyID()
+	url := user.KeyID()
 	expected := "https://try.gitea.io/api/v1/activitypub/user-id/1#main-key"
 	assert.Equal(t, expected, url)
 }

modules/activitypub/client.go

@@ -89,6 +89,7 @@ func NewClientFactory() (c *ClientFactory, err error) {
 
 type APClientFactory interface {
 	WithKeys(ctx context.Context, user *user_model.User, pubID string) (APClient, error)
+	WithKeysDirect(ctx context.Context, privateKey, pubID string) (APClient, error)
 }
 
 // Client struct
@@ -103,12 +104,8 @@ type Client struct {
 }
 
 // NewRequest function
-func (cf *ClientFactory) WithKeys(ctx context.Context, user *user_model.User, pubID string) (APClient, error) {
-	priv, err := GetPrivateKey(ctx, user)
-	if err != nil {
-		return nil, err
-	}
-	privPem, _ := pem.Decode([]byte(priv))
+func (cf *ClientFactory) WithKeysDirect(ctx context.Context, privateKey, pubID string) (APClient, error) {
+	privPem, _ := pem.Decode([]byte(privateKey))
 	privParsed, err := x509.ParsePKCS1PrivateKey(privPem.Bytes)
 	if err != nil {
 		return nil, err
@@ -126,6 +123,14 @@ func (cf *ClientFactory) WithKeys(ctx context.Context, user *user_model.User, pu
 	return &c, nil
 }
 
+func (cf *ClientFactory) WithKeys(ctx context.Context, user *user_model.User, pubID string) (APClient, error) {
+	priv, err := GetPrivateKey(ctx, user)
+	if err != nil {
+		return nil, err
+	}
+	return cf.WithKeysDirect(ctx, priv, pubID)
+}
+
 // NewRequest function
 func (c *Client) newRequest(method string, b []byte, to string) (req *http.Request, err error) {
 	buf := bytes.NewBuffer(b)
@@ -149,12 +154,14 @@ func (c *Client) Post(b []byte, to string) (resp *http.Response, err error) {
 		return nil, err
 	}
 
-	signer, _, err := httpsig.NewSigner(c.algs, c.digestAlg, c.postHeaders, httpsig.Signature, httpsigExpirationTime)
-	if err != nil {
-		return nil, err
-	}
-	if err := signer.SignRequest(c.priv, c.pubID, req, b); err != nil {
-		return nil, err
+	if c.pubID != "" {
+		signer, _, err := httpsig.NewSigner(c.algs, c.digestAlg, c.postHeaders, httpsig.Signature, httpsigExpirationTime)
+		if err != nil {
+			return nil, err
+		}
+		if err := signer.SignRequest(c.priv, c.pubID, req, b); err != nil {
+			return nil, err
+		}
 	}
 
 	resp, err = c.client.Do(req)
@@ -167,12 +174,15 @@ func (c *Client) Get(to string) (resp *http.Response, err error) {
 	if req, err = c.newRequest(http.MethodGet, nil, to); err != nil {
 		return nil, err
 	}
-	signer, _, err := httpsig.NewSigner(c.algs, c.digestAlg, c.getHeaders, httpsig.Signature, httpsigExpirationTime)
-	if err != nil {
-		return nil, err
-	}
-	if err := signer.SignRequest(c.priv, c.pubID, req, nil); err != nil {
-		return nil, err
+
+	if c.pubID != "" {
+		signer, _, err := httpsig.NewSigner(c.algs, c.digestAlg, c.getHeaders, httpsig.Signature, httpsigExpirationTime)
+		if err != nil {
+			return nil, err
+		}
+		if err := signer.SignRequest(c.priv, c.pubID, req, nil); err != nil {
+			return nil, err
+		}
 	}
 
 	resp, err = c.client.Do(req)

modules/structs/activitypub.go

@@ -1,4 +1,5 @@
 // Copyright 2022 The Gitea Authors. All rights reserved.
+// Copyright 2024 The Forgejo Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
 package structs
@@ -7,3 +8,15 @@ package structs
 type ActivityPub struct {
 	Context string `json:"@context"`
 }
+
+type APRemoteFollowOption struct {
+	Target string `json:"target"`
+}
+
+type APPersonFollowItem struct {
+	ActorID string `json:"actor_id"`
+	Note    string `json:"note"`
+
+	OriginalURL  string `json:"original_url"`
+	OriginalItem string `json:"original_item"`
+}

modules/test/distant_federation_server_mock.go

@@ -10,56 +10,79 @@ import (
 	"net/http/httptest"
 	"strings"
 	"testing"
+
+	"forgejo.org/modules/util"
 )
 
 type FederationServerMockPerson struct {
-	ID     int64
-	Name   string
-	PubKey string
+	ID      int64
+	Name    string
+	PubKey  string
+	PrivKey string
 }
 type FederationServerMockRepository struct {
 	ID int64
 }
+type ApActorMock struct {
+	PrivKey string
+	PubKey  string
+}
 type FederationServerMock struct {
+	ApActor      ApActorMock
 	Persons      []FederationServerMockPerson
 	Repositories []FederationServerMockRepository
 	LastPost     string
 }
 
 func NewFederationServerMockPerson(id int64, name string) FederationServerMockPerson {
+	priv, pub, _ := util.GenerateKeyPair(3072)
 	return FederationServerMockPerson{
-		ID:   id,
-		Name: name,
-		PubKey: `"-----BEGIN PUBLIC KEY-----\nMIIBojANBgkqhkiG9w0BAQEFAAOCAY8AMIIBigKCAYEA18H5s7N6ItZUAh9tneII\nIuZdTTa3cZlLa/9ejWAHTkcp3WLW+/zbsumlMrWYfBy2/yTm56qasWt38iY4D6ul\n` +
-			`CPiwhAqX3REvVq8tM79a2CEqZn9ka6vuXoDgBg/sBf/BUWqf7orkjUXwk/U0Egjf\nk5jcurF4vqf1u+rlAHH37dvSBaDjNj6Qnj4OP12bjfaY/yvs7+jue/eNXFHjzN4E\n` +
-			`T2H4B/yeKTJ4UuAwTlLaNbZJul2baLlHelJPAsxiYaziVuV5P+IGWckY6RSerRaZ\nAkc4mmGGtjAyfN9aewe+lNVfwS7ElFx546PlLgdQgjmeSwLX8FWxbPE5A/PmaXCs\n` +
-			`nx+nou+3dD7NluULLtdd7K+2x02trObKXCAzmi5/Dc+yKTzpFqEz+hLNCz7TImP/\ncK//NV9Q+X67J9O27baH9R9ZF4zMw8rv2Pg0WLSw1z7lLXwlgIsDapeMCsrxkVO4\n` +
-			`LXX5AQ1xQNtlssnVoUBqBrvZsX2jUUKUocvZqMGuE4hfAgMBAAE=\n-----END PUBLIC KEY-----\n"`,
+		ID:      id,
+		Name:    name,
+		PubKey:  pub,
+		PrivKey: priv,
 	}
 }
 
+func (p *FederationServerMockPerson) KeyID(host string) string {
+	return fmt.Sprintf("%[1]v/api/v1/activitypub/user-id/%[2]v#main-key", host, p.ID)
+}
+
 func NewFederationServerMockRepository(id int64) FederationServerMockRepository {
 	return FederationServerMockRepository{
 		ID: id,
 	}
 }
 
+func NewApActorMock() ApActorMock {
+	priv, pub, _ := util.GenerateKeyPair(1024)
+	return ApActorMock{
+		PrivKey: priv,
+		PubKey:  pub,
+	}
+}
+
+func (u *ApActorMock) KeyID(host string) string {
+	return fmt.Sprintf("%[1]v/api/v1/activitypub/actor#main-key", host)
+}
+
 func (p FederationServerMockPerson) marshal(host string) string {
 	return fmt.Sprintf(`{"@context":["https://www.w3.org/ns/activitystreams","https://w3id.org/security/v1"],`+
-		`"id":"http://%[1]v/api/activitypub/user-id/%[2]v",`+
+		`"id":"http://%[1]v/api/v1/activitypub/user-id/%[2]v",`+
 		`"type":"Person",`+
 		`"icon":{"type":"Image","mediaType":"image/png","url":"http://%[1]v/avatars/1bb05d9a5f6675ed0272af9ea193063c"},`+
 		`"url":"http://%[1]v/%[2]v",`+
-		`"inbox":"http://%[1]v/api/activitypub/user-id/%[2]v/inbox",`+
-		`"outbox":"http://%[1]v/api/activitypub/user-id/%[2]v/outbox",`+
+		`"inbox":"http://%[1]v/api/v1/activitypub/user-id/%[2]v/inbox",`+
+		`"outbox":"http://%[1]v/api/v1/activitypub/user-id/%[2]v/outbox",`+
 		`"preferredUsername":"%[3]v",`+
-		`"publicKey":{"id":"http://%[1]v/api/activitypub/user-id/%[2]v#main-key",`+
-		`"owner":"http://%[1]v/api/activitypub/user-id/%[2]v",`+
-		`"publicKeyPem":%[4]v}}`, host, p.ID, p.Name, p.PubKey)
+		`"publicKey":{"id":"http://%[1]v/api/v1/activitypub/user-id/%[2]v#main-key",`+
+		`"owner":"http://%[1]v/api/v1/activitypub/user-id/%[2]v",`+
+		`"publicKeyPem":%[4]q}}`, host, p.ID, p.Name, p.PubKey)
 }
 
 func NewFederationServerMock() *FederationServerMock {
 	return &FederationServerMock{
+		ApActor: NewApActorMock(),
 		Persons: []FederationServerMockPerson{
 			NewFederationServerMockPerson(15, "stargoose1"),
 			NewFederationServerMockPerson(30, "stargoose2"),
@@ -71,8 +94,18 @@ func NewFederationServerMock() *FederationServerMock {
 	}
 }
 
+func (mock *FederationServerMock) recordLastPost(t *testing.T, req *http.Request) {
+	buf := new(strings.Builder)
+	_, err := io.Copy(buf, req.Body)
+	if err != nil {
+		t.Errorf("Error reading body: %q", err)
+	}
+	mock.LastPost = strings.ReplaceAll(buf.String(), req.Host, "DISTANT_FEDERATION_HOST")
+}
+
 func (mock *FederationServerMock) DistantServer(t *testing.T) *httptest.Server {
 	federatedRoutes := http.NewServeMux()
+
 	federatedRoutes.HandleFunc("/.well-known/nodeinfo",
 		func(res http.ResponseWriter, req *http.Request) {
 			// curl -H "Accept: application/json" https://federated-repo.prod.meissa.de/.well-known/nodeinfo
@@ -87,30 +120,28 @@ func (mock *FederationServerMock) DistantServer(t *testing.T) *httptest.Server {
 				`"protocols":["activitypub"],"services":{"inbound":[],"outbound":["rss2.0"]},`+
 				`"openRegistrations":true,"usage":{"users":{"total":14,"activeHalfyear":2}},"metadata":{}}`)
 		})
+
 	for _, person := range mock.Persons {
 		federatedRoutes.HandleFunc(fmt.Sprintf("/api/v1/activitypub/user-id/%v", person.ID),
 			func(res http.ResponseWriter, req *http.Request) {
 				// curl -H "Accept: application/json" https://federated-repo.prod.meissa.de/api/v1/activitypub/user-id/2
 				fmt.Fprint(res, person.marshal(req.Host))
 			})
-	}
-	for _, repository := range mock.Repositories {
-		federatedRoutes.HandleFunc(fmt.Sprintf("/api/v1/activitypub/repository-id/%v/inbox", repository.ID),
+		federatedRoutes.HandleFunc(fmt.Sprintf("POST /api/v1/activitypub/user-id/%v/inbox", person.ID),
 			func(res http.ResponseWriter, req *http.Request) {
-				if req.Method != "POST" {
-					t.Errorf("POST expected at: %q", req.URL.EscapedPath())
-				}
-				buf := new(strings.Builder)
-				_, err := io.Copy(buf, req.Body)
-				if err != nil {
-					t.Errorf("Error reading body: %q", err)
-				}
-				mock.LastPost = buf.String()
+				mock.recordLastPost(t, req)
+			})
+	}
+
+	for _, repository := range mock.Repositories {
+		federatedRoutes.HandleFunc(fmt.Sprintf("POST /api/v1/activitypub/repository-id/%v/inbox", repository.ID),
+			func(res http.ResponseWriter, req *http.Request) {
+				mock.recordLastPost(t, req)
 			})
 	}
 	federatedRoutes.HandleFunc("/",
 		func(res http.ResponseWriter, req *http.Request) {
-			t.Errorf("Unhandled request: %q", req.URL.EscapedPath())
+			t.Errorf("Unhandled %v request: %q", req.Method, req.URL.EscapedPath())
 		})
 	federatedSrv := httptest.NewServer(federatedRoutes)
 	return federatedSrv

routers/api/v1/activitypub/actor.go

@@ -32,7 +32,7 @@ func Actor(ctx *context.APIContext) {
 	actor := ap.ActorNew(ap.IRI(link), ap.ApplicationType)
 
 	actor.PreferredUsername = ap.NaturalLanguageValuesNew()
-	err := actor.PreferredUsername.Set("en", ap.Content(setting.Domain))
+	err := actor.PreferredUsername.Set("en", ap.Content("ghost"))
 	if err != nil {
 		ctx.ServerError("PreferredUsername.Set", err)
 		return
@@ -41,8 +41,6 @@ func Actor(ctx *context.APIContext) {
 	actor.URL = ap.IRI(setting.AppURL)
 
 	actor.Inbox = ap.IRI(link + "/inbox")
-	actor.Outbox = ap.IRI(link + "/outbox")
-
 	actor.PublicKey.ID = ap.IRI(link + "#main-key")
 	actor.PublicKey.Owner = ap.IRI(link)
 

routers/api/v1/activitypub/reqsignature.go

@@ -4,132 +4,17 @@
 package activitypub
 
 import (
-	"crypto"
-	"crypto/x509"
-	"database/sql"
-	"encoding/pem"
-	"errors"
-	"fmt"
 	"net/http"
-	"net/url"
 
-	"forgejo.org/models/db"
-	"forgejo.org/models/forgefed"
-	"forgejo.org/models/user"
-	"forgejo.org/modules/activitypub"
-	fm "forgejo.org/modules/forgefed"
 	"forgejo.org/modules/log"
 	"forgejo.org/modules/setting"
 	gitea_context "forgejo.org/services/context"
 	"forgejo.org/services/federation"
 
 	"github.com/42wim/httpsig"
-	ap "github.com/go-ap/activitypub"
 )
 
-func decodePublicKeyPem(pubKeyPem string) ([]byte, error) {
-	block, _ := pem.Decode([]byte(pubKeyPem))
-	if block == nil || block.Type != "PUBLIC KEY" {
-		return nil, errors.New("could not decode publicKeyPem to PUBLIC KEY pem block type")
-	}
-
-	return block.Bytes, nil
-}
-
-func getFederatedUser(ctx *gitea_context.APIContext, person *ap.Person, federationHost *forgefed.FederationHost) (*user.FederatedUser, error) {
-	personID, err := fm.NewPersonID(person.ID.String(), string(federationHost.NodeInfo.SoftwareName))
-	if err != nil {
-		return nil, err
-	}
-	_, federatedUser, err := user.FindFederatedUser(ctx, personID.ID, federationHost.ID)
-	if err != nil {
-		return nil, err
-	}
-
-	if federatedUser != nil {
-		return federatedUser, nil
-	}
-
-	_, newFederatedUser, err := federation.CreateUserFromAP(ctx, personID, federationHost.ID)
-	if err != nil {
-		return nil, err
-	}
-
-	return newFederatedUser, nil
-}
-
-func storePublicKey(ctx *gitea_context.APIContext, person *ap.Person, pubKeyBytes []byte) error {
-	federationHost, err := federation.GetFederationHostForURI(ctx, person.ID.String())
-	if err != nil {
-		return err
-	}
-
-	if person.Type == ap.ActivityVocabularyType("Application") {
-		federationHost.KeyID = sql.NullString{
-			String: person.PublicKey.ID.String(),
-			Valid:  true,
-		}
-
-		federationHost.PublicKey = sql.Null[sql.RawBytes]{
-			V:     pubKeyBytes,
-			Valid: true,
-		}
-
-		_, err = db.GetEngine(ctx).ID(federationHost.ID).Update(federationHost)
-		if err != nil {
-			return err
-		}
-	} else if person.Type == ap.ActivityVocabularyType("Person") {
-		federatedUser, err := getFederatedUser(ctx, person, federationHost)
-		if err != nil {
-			return err
-		}
-
-		federatedUser.KeyID = sql.NullString{
-			String: person.PublicKey.ID.String(),
-			Valid:  true,
-		}
-
-		federatedUser.PublicKey = sql.Null[sql.RawBytes]{
-			V:     pubKeyBytes,
-			Valid: true,
-		}
-
-		_, err = db.GetEngine(ctx).ID(federatedUser.ID).Update(federatedUser)
-		if err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-func getPublicKeyFromResponse(b []byte, keyID *url.URL) (person *ap.Person, pubKeyBytes []byte, p crypto.PublicKey, err error) {
-	person = ap.PersonNew(ap.IRI(keyID.String()))
-	err = person.UnmarshalJSON(b)
-	if err != nil {
-		return nil, nil, nil, fmt.Errorf("ActivityStreams type cannot be converted to one known to have publicKey property: %w", err)
-	}
-
-	pubKey := person.PublicKey
-	if pubKey.ID.String() != keyID.String() {
-		return nil, nil, nil, fmt.Errorf("cannot find publicKey with id: %s in %s", keyID, string(b))
-	}
-
-	pubKeyBytes, err = decodePublicKeyPem(pubKey.PublicKeyPem)
-	if err != nil {
-		return nil, nil, nil, err
-	}
-
-	p, err = x509.ParsePKIXPublicKey(pubKeyBytes)
-	if err != nil {
-		return nil, nil, nil, err
-	}
-
-	return person, pubKeyBytes, p, err
-}
-
-func verifyHTTPSignatures(ctx *gitea_context.APIContext) (authenticated bool, err error) {
+func verifyHTTPUserOrInstanceSignature(ctx *gitea_context.APIContext) (authenticated bool, err error) {
 	if !setting.Federation.SignatureEnforced {
 		return true, nil
 	}
@@ -142,84 +27,64 @@ func verifyHTTPSignatures(ctx *gitea_context.APIContext) (authenticated bool, er
 		return false, err
 	}
 
-	ID := v.KeyId()
-	idIRI, err := url.Parse(ID)
+	signatureAlgorithm := httpsig.Algorithm(setting.Federation.SignatureAlgorithms[0])
+	pubKey, err := federation.FindOrCreateFederatedUserKey(ctx.Base, v.KeyId())
+	if err != nil || pubKey == nil {
+		pubKey, err = federation.FindOrCreateFederationHostKey(ctx.Base, v.KeyId())
+		if err != nil {
+			return false, err
+		}
+	}
+
+	err = v.Verify(pubKey, signatureAlgorithm)
+	if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+func verifyHTTPUserSignature(ctx *gitea_context.APIContext) (authenticated bool, err error) {
+	if !setting.Federation.SignatureEnforced {
+		return true, nil
+	}
+
+	r := ctx.Req
+
+	// 1. Figure out what key we need to verify
+	v, err := httpsig.NewVerifier(r)
 	if err != nil {
 		return false, err
 	}
 
 	signatureAlgorithm := httpsig.Algorithm(setting.Federation.SignatureAlgorithms[0])
-
-	// 2. Fetch the public key of the other actor
-	// Try if the signing actor is an already known federated user
-	_, federationUser, err := user.FindFederatedUserByKeyID(ctx, idIRI.String())
+	pubKey, err := federation.FindOrCreateFederatedUserKey(ctx.Base, v.KeyId())
 	if err != nil {
 		return false, err
 	}
 
-	if federationUser != nil && federationUser.PublicKey.Valid {
-		pubKey, err := x509.ParsePKIXPublicKey(federationUser.PublicKey.V)
-		if err != nil {
-			return false, err
-		}
-
-		authenticated = v.Verify(pubKey, signatureAlgorithm) == nil
-		return authenticated, err
-	}
-
-	// Try if the signing actor is an already known federation host
-	federationHost, err := forgefed.FindFederationHostByKeyID(ctx, idIRI.String())
+	err = v.Verify(pubKey, signatureAlgorithm)
 	if err != nil {
 		return false, err
 	}
-
-	if federationHost != nil && federationHost.PublicKey.Valid {
-		pubKey, err := x509.ParsePKIXPublicKey(federationHost.PublicKey.V)
-		if err != nil {
-			return false, err
-		}
-
-		authenticated = v.Verify(pubKey, signatureAlgorithm) == nil
-		return authenticated, err
-	}
-
-	// Fetch missing public key
-	actionsUser := user.NewAPServerActor()
-	clientFactory, err := activitypub.GetClientFactory(ctx)
-	if err != nil {
-		return false, err
-	}
-
-	apClient, err := clientFactory.WithKeys(ctx, actionsUser, actionsUser.APActorKeyID())
-	if err != nil {
-		return false, err
-	}
-
-	b, err := apClient.GetBody(idIRI.String())
-	if err != nil {
-		return false, err
-	}
-
-	person, pubKeyBytes, pubKey, err := getPublicKeyFromResponse(b, idIRI)
-	if err != nil {
-		return false, err
-	}
-
-	authenticated = v.Verify(pubKey, signatureAlgorithm) == nil
-	if authenticated {
-		err = storePublicKey(ctx, person, pubKeyBytes)
-		if err != nil {
-			return false, err
-		}
-	}
-
-	return authenticated, err
+	return true, nil
 }
 
 // ReqHTTPSignature function
-func ReqHTTPSignature() func(ctx *gitea_context.APIContext) {
+func ReqHTTPUserOrInstanceSignature() func(ctx *gitea_context.APIContext) {
 	return func(ctx *gitea_context.APIContext) {
-		if authenticated, err := verifyHTTPSignatures(ctx); err != nil {
+		if authenticated, err := verifyHTTPUserOrInstanceSignature(ctx); err != nil {
+			log.Warn("verifyHttpSignatures failed: %v", err)
+			ctx.Error(http.StatusBadRequest, "reqSignature", "request signature verification failed")
+		} else if !authenticated {
+			ctx.Error(http.StatusForbidden, "reqSignature", "request signature verification failed")
+		}
+	}
+}
+
+// ReqHTTPSignature function
+func ReqHTTPUserSignature() func(ctx *gitea_context.APIContext) {
+	return func(ctx *gitea_context.APIContext) {
+		if authenticated, err := verifyHTTPUserSignature(ctx); err != nil {
 			log.Warn("verifyHttpSignatures failed: %v", err)
 			ctx.Error(http.StatusBadRequest, "reqSignature", "request signature verification failed")
 		} else if !authenticated {

routers/api/v1/api.go

@@ -92,6 +92,7 @@ import (
 	_ "forgejo.org/routers/api/v1/swagger" // for swagger generation
 
 	"code.forgejo.org/go-chi/binding"
+	ap "github.com/go-ap/activitypub"
 )
 
 func sudo() func(ctx *context.APIContext) {
@@ -826,24 +827,22 @@ func Routes() *web.Route {
 		if setting.Federation.Enabled {
 			m.Get("/nodeinfo", misc.NodeInfo)
 			m.Group("/activitypub", func() {
-				// deprecated, remove in 1.20, use /user-id/{user-id} instead
-				m.Group("/user/{username}", func() {
-					m.Get("", activitypub.ReqHTTPSignature(), activitypub.Person)
-					m.Post("/inbox", activitypub.ReqHTTPSignature(), activitypub.PersonInbox)
-				}, context.UserAssignmentAPI(), checkTokenPublicOnly())
 				m.Group("/user-id/{user-id}", func() {
-					m.Get("", activitypub.ReqHTTPSignature(), activitypub.Person)
-					m.Post("/inbox", activitypub.ReqHTTPSignature(), activitypub.PersonInbox)
+					m.Get("", activitypub.ReqHTTPUserOrInstanceSignature(), activitypub.Person)
+					m.Post("/inbox",
+						activitypub.ReqHTTPUserSignature(),
+						bind(ap.Activity{}),
+						activitypub.PersonInbox)
 				}, context.UserIDAssignmentAPI(), checkTokenPublicOnly())
 				m.Group("/actor", func() {
 					m.Get("", activitypub.Actor)
-					m.Post("/inbox", activitypub.ReqHTTPSignature(), activitypub.ActorInbox)
+					m.Post("/inbox", activitypub.ReqHTTPUserOrInstanceSignature(), activitypub.ActorInbox)
 				})
 				m.Group("/repository-id/{repository-id}", func() {
-					m.Get("", activitypub.ReqHTTPSignature(), activitypub.Repository)
+					m.Get("", activitypub.ReqHTTPUserSignature(), activitypub.Repository)
 					m.Post("/inbox",
 						bind(forgefed.ForgeLike{}),
-						activitypub.ReqHTTPSignature(),
+						activitypub.ReqHTTPUserSignature(),
 						activitypub.RepositoryInbox)
 				}, context.RepositoryIDAssignmentAPI())
 			}, tokenRequiresScopes(auth_model.AccessTokenScopeCategoryActivityPub))

routers/web/webfinger.go

@@ -58,7 +58,33 @@ func WebfingerQuery(ctx *context.Context) {
 			return
 		}
 
+		// Instance actor
+		if parts[0] == "ghost" {
+			aliases := []string{
+				appURL.String() + "api/v1/activitypub/actor",
+			}
+
+			links := []*webfingerLink{
+				{
+					Rel:  "self",
+					Type: "application/activity+json",
+					Href: appURL.String() + "api/v1/activitypub/actor",
+				},
+			}
+
+			ctx.Resp.Header().Add("Access-Control-Allow-Origin", "*")
+			ctx.JSON(http.StatusOK, &webfingerJRD{
+				Subject: fmt.Sprintf("acct:%s@%s", "ghost", appURL.Host),
+				Aliases: aliases,
+				Links:   links,
+			})
+			ctx.Resp.Header().Set("Content-Type", "application/jrd+json")
+
+			return
+		}
+
 		u, err = user_model.GetUserByName(ctx, parts[0])
+
 	case "mailto":
 		u, err = user_model.GetUserByEmail(ctx, resource.Opaque)
 		if u != nil && u.KeepEmailPrivate {

services/federation/federation_service.go

@@ -5,15 +5,12 @@ package federation
 
 import (
 	"context"
-	"errors"
+	"database/sql"
 	"fmt"
-	"net/http"
 	"net/url"
 	"strings"
-	"time"
 
 	"forgejo.org/models/forgefed"
-	"forgejo.org/models/repo"
 	"forgejo.org/models/user"
 	"forgejo.org/modules/activitypub"
 	"forgejo.org/modules/auth/password"
@@ -21,91 +18,84 @@ import (
 	"forgejo.org/modules/log"
 	"forgejo.org/modules/setting"
 	"forgejo.org/modules/validation"
+	context_service "forgejo.org/services/context"
 
 	"github.com/google/uuid"
 )
 
-// ProcessLikeActivity receives a ForgeLike activity and does the following:
-// Validation of the activity
-// Creation of a (remote) federationHost if not existing
-// Creation of a forgefed Person if not existing
-// Validation of incoming RepositoryID against Local RepositoryID
-// Star the repo if it wasn't already stared
-// Do some mitigation against out of order attacks
-func ProcessLikeActivity(ctx context.Context, form any, repositoryID int64) (int, string, error) {
-	activity := form.(*fm.ForgeLike)
-	if res, err := validation.IsValid(activity); !res {
-		return http.StatusNotAcceptable, "Invalid activity", err
-	}
-	log.Info("Activity validated:%v", activity)
+func Init() error {
+	return nil
+}
 
-	// parse actorID (person)
-	actorURI := activity.Actor.GetID().String()
-	log.Info("actorURI was: %v", actorURI)
-	federationHost, err := GetFederationHostForURI(ctx, actorURI)
+func FindOrCreateFederationHost(ctx *context_service.Base, actorURI string) (*forgefed.FederationHost, error) {
+	rawActorID, err := fm.NewActorID(actorURI)
 	if err != nil {
-		return http.StatusInternalServerError, "Wrong FederationHost", err
+		return nil, err
 	}
-	if !activity.IsNewer(federationHost.LatestActivity) {
-		return http.StatusNotAcceptable, "Activity out of order.", errors.New("Activity already processed")
+	federationHost, err := forgefed.FindFederationHostByFqdnAndPort(ctx, rawActorID.Host, rawActorID.HostPort)
+	if err != nil {
+		return nil, err
+	}
+	if federationHost == nil {
+		result, err := createFederationHostFromAP(ctx, rawActorID)
+		if err != nil {
+			return nil, err
+		}
+		federationHost = result
+	}
+	return federationHost, nil
+}
+
+func FindOrCreateFederatedUser(ctx *context_service.Base, actorURI string) (*user.User, *user.FederatedUser, *forgefed.FederationHost, error) {
+	user, federatedUser, federationHost, err := findFederatedUser(ctx, actorURI)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	personID, err := fm.NewPersonID(actorURI, string(federationHost.NodeInfo.SoftwareName))
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	if user != nil {
+		log.Trace("Found local federatedUser: %#v", user)
+	} else {
+		user, federatedUser, err = createUserFromAP(ctx, personID, federationHost.ID)
+		if err != nil {
+			return nil, nil, nil, err
+		}
+		log.Trace("Created federatedUser from ap: %#v", user)
+	}
+	log.Trace("Got user: %v", user.Name)
+
+	return user, federatedUser, federationHost, nil
+}
+
+func findFederatedUser(ctx *context_service.Base, actorURI string) (*user.User, *user.FederatedUser, *forgefed.FederationHost, error) {
+	federationHost, err := FindOrCreateFederationHost(ctx, actorURI)
+	if err != nil {
+		return nil, nil, nil, err
 	}
 	actorID, err := fm.NewPersonID(actorURI, string(federationHost.NodeInfo.SoftwareName))
 	if err != nil {
-		return http.StatusNotAcceptable, "Invalid PersonID", err
+		return nil, nil, nil, err
 	}
-	log.Info("Actor accepted:%v", actorID)
 
-	// parse objectID (repository)
-	objectID, err := fm.NewRepositoryID(activity.Object.GetID().String(), string(forgefed.ForgejoSourceType))
+	user, federatedUser, err := user.FindFederatedUser(ctx, actorID.ID, federationHost.ID)
 	if err != nil {
-		return http.StatusNotAcceptable, "Invalid objectId", err
-	}
-	if objectID.ID != fmt.Sprint(repositoryID) {
-		return http.StatusNotAcceptable, "Invalid objectId", err
-	}
-	log.Info("Object accepted:%v", objectID)
-
-	// Check if user already exists
-	user, _, err := user.FindFederatedUser(ctx, actorID.ID, federationHost.ID)
-	if err != nil {
-		return http.StatusInternalServerError, "Searching for user failed", err
-	}
-	if user != nil {
-		log.Info("Found local federatedUser: %v", user)
-	} else {
-		user, _, err = CreateUserFromAP(ctx, actorID, federationHost.ID)
-		if err != nil {
-			return http.StatusInternalServerError, "Error creating federatedUser", err
-		}
-		log.Info("Created federatedUser from ap: %v", user)
-	}
-	log.Info("Got user:%v", user.Name)
-
-	// execute the activity if the repo was not stared already
-	alreadyStared := repo.IsStaring(ctx, user.ID, repositoryID)
-	if !alreadyStared {
-		err = repo.StarRepo(ctx, user.ID, repositoryID, true)
-		if err != nil {
-			return http.StatusNotAcceptable, "Error staring", err
-		}
-	}
-	federationHost.LatestActivity = activity.StartTime
-	err = forgefed.UpdateFederationHost(ctx, federationHost)
-	if err != nil {
-		return http.StatusNotAcceptable, "Error updating federatedHost", err
+		return nil, nil, nil, err
 	}
 
-	return 0, "", nil
+	return user, federatedUser, federationHost, nil
 }
 
-func CreateFederationHostFromAP(ctx context.Context, actorID fm.ActorID) (*forgefed.FederationHost, error) {
+func createFederationHostFromAP(ctx context.Context, actorID fm.ActorID) (*forgefed.FederationHost, error) {
 	actionsUser := user.NewAPServerActor()
 	clientFactory, err := activitypub.GetClientFactory(ctx)
 	if err != nil {
 		return nil, err
 	}
 
-	client, err := clientFactory.WithKeys(ctx, actionsUser, actionsUser.APActorKeyID())
+	client, err := clientFactory.WithKeys(ctx, actionsUser, actionsUser.KeyID())
 	if err != nil {
 		return nil, err
 	}
@@ -130,6 +120,7 @@ func CreateFederationHostFromAP(ctx context.Context, actorID fm.ActorID) (*forge
 		return nil, err
 	}
 
+	// TODO: we should get key material here also to have it immediately
 	result, err := forgefed.NewFederationHost(actorID.Host, nodeInfo, actorID.HostPort, actorID.HostSchema)
 	if err != nil {
 		return nil, err
@@ -143,34 +134,14 @@ func CreateFederationHostFromAP(ctx context.Context, actorID fm.ActorID) (*forge
 	return &result, nil
 }
 
-func GetFederationHostForURI(ctx context.Context, actorURI string) (*forgefed.FederationHost, error) {
-	log.Info("Input was: %v", actorURI)
-	rawActorID, err := fm.NewActorID(actorURI)
-	if err != nil {
-		return nil, err
-	}
-	federationHost, err := forgefed.FindFederationHostByFqdnAndPort(ctx, rawActorID.Host, rawActorID.HostPort)
-	if err != nil {
-		return nil, err
-	}
-	if federationHost == nil {
-		result, err := CreateFederationHostFromAP(ctx, rawActorID)
-		if err != nil {
-			return nil, err
-		}
-		federationHost = result
-	}
-	return federationHost, nil
-}
-
-func CreateUserFromAP(ctx context.Context, personID fm.PersonID, federationHostID int64) (*user.User, *user.FederatedUser, error) {
+func fetchUserFromAP(ctx context.Context, personID fm.PersonID, federationHostID int64) (*user.User, *user.FederatedUser, error) {
 	actionsUser := user.NewAPServerActor()
 	clientFactory, err := activitypub.GetClientFactory(ctx)
 	if err != nil {
 		return nil, nil, err
 	}
 
-	apClient, err := clientFactory.WithKeys(ctx, actionsUser, actionsUser.APActorKeyID())
+	apClient, err := clientFactory.WithKeys(ctx, actionsUser, actionsUser.KeyID())
 	if err != nil {
 		return nil, nil, err
 	}
@@ -216,6 +187,11 @@ func CreateUserFromAP(ctx context.Context, personID fm.PersonID, federationHostI
 		return nil, nil, err
 	}
 
+	pubKeyBytes, err := decodePublicKeyPem(person.PublicKey.PublicKeyPem)
+	if err != nil {
+		return nil, nil, err
+	}
+
 	newUser := user.User{
 		LowerName:                    strings.ToLower(name),
 		Name:                         name,
@@ -234,86 +210,30 @@ func CreateUserFromAP(ctx context.Context, personID fm.PersonID, federationHostI
 		FederationHostID:      federationHostID,
 		InboxPath:             inbox.Path,
 		NormalizedOriginalURL: personID.AsURI(),
+		KeyID: sql.NullString{
+			String: person.PublicKey.ID.String(),
+			Valid:  true,
+		},
+		PublicKey: sql.Null[sql.RawBytes]{
+			V:     pubKeyBytes,
+			Valid: true,
+		},
 	}
 
-	err = user.CreateFederatedUser(ctx, &newUser, &federatedUser)
+	log.Info("Fetch federatedUser:%q", federatedUser)
+	return &newUser, &federatedUser, nil
+}
+
+func createUserFromAP(ctx context.Context, personID fm.PersonID, federationHostID int64) (*user.User, *user.FederatedUser, error) {
+	newUser, federatedUser, err := fetchUserFromAP(ctx, personID, federationHostID)
+	if err != nil {
+		return nil, nil, err
+	}
+	err = user.CreateFederatedUser(ctx, newUser, federatedUser)
 	if err != nil {
 		return nil, nil, err
 	}
 
 	log.Info("Created federatedUser:%q", federatedUser)
-	return &newUser, &federatedUser, nil
-}
-
-// Create or update a list of FollowingRepo structs
-func StoreFollowingRepoList(ctx context.Context, localRepoID int64, followingRepoList []string) (int, string, error) {
-	followingRepos := make([]*repo.FollowingRepo, 0, len(followingRepoList))
-	for _, uri := range followingRepoList {
-		federationHost, err := GetFederationHostForURI(ctx, uri)
-		if err != nil {
-			return http.StatusInternalServerError, "Wrong FederationHost", err
-		}
-		followingRepoID, err := fm.NewRepositoryID(uri, string(federationHost.NodeInfo.SoftwareName))
-		if err != nil {
-			return http.StatusNotAcceptable, "Invalid federated repo", err
-		}
-		followingRepo, err := repo.NewFollowingRepo(localRepoID, followingRepoID.ID, federationHost.ID, uri)
-		if err != nil {
-			return http.StatusNotAcceptable, "Invalid federated repo", err
-		}
-		followingRepos = append(followingRepos, &followingRepo)
-	}
-
-	if err := repo.StoreFollowingRepos(ctx, localRepoID, followingRepos); err != nil {
-		return 0, "", err
-	}
-
-	return 0, "", nil
-}
-
-func DeleteFollowingRepos(ctx context.Context, localRepoID int64) error {
-	return repo.StoreFollowingRepos(ctx, localRepoID, []*repo.FollowingRepo{})
-}
-
-func SendLikeActivities(ctx context.Context, doer user.User, repoID int64) error {
-	followingRepos, err := repo.FindFollowingReposByRepoID(ctx, repoID)
-	log.Info("Federated Repos is: %v", followingRepos)
-	if err != nil {
-		return err
-	}
-
-	likeActivityList := make([]fm.ForgeLike, 0)
-	for _, followingRepo := range followingRepos {
-		log.Info("Found following repo: %v", followingRepo)
-		target := followingRepo.URI
-		likeActivity, err := fm.NewForgeLike(doer.APActorID(), target, time.Now())
-		if err != nil {
-			return err
-		}
-		likeActivityList = append(likeActivityList, likeActivity)
-	}
-
-	apclientFactory, err := activitypub.GetClientFactory(ctx)
-	if err != nil {
-		return err
-	}
-
-	apclient, err := apclientFactory.WithKeys(ctx, &doer, doer.APActorKeyID())
-	if err != nil {
-		return err
-	}
-	for i, activity := range likeActivityList {
-		activity.StartTime = activity.StartTime.Add(time.Duration(i) * time.Second)
-		json, err := activity.MarshalJSON()
-		if err != nil {
-			return err
-		}
-
-		_, err = apclient.Post(json, fmt.Sprintf("%s/inbox", activity.Object))
-		if err != nil {
-			log.Error("error %v while sending activity: %q", err, activity)
-		}
-	}
-
-	return nil
+	return newUser, federatedUser, nil
 }

services/federation/repo_like.go

@@ -0,0 +1,146 @@
+// Copyright 2024 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package federation
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"time"
+
+	"forgejo.org/models/forgefed"
+	"forgejo.org/models/repo"
+	"forgejo.org/models/user"
+	"forgejo.org/modules/activitypub"
+	fm "forgejo.org/modules/forgefed"
+	"forgejo.org/modules/log"
+	"forgejo.org/modules/validation"
+	context_service "forgejo.org/services/context"
+)
+
+// ProcessLikeActivity receives a ForgeLike activity and does the following:
+// Validation of the activity
+// Creation of a (remote) federationHost if not existing
+// Creation of a forgefed Person if not existing
+// Validation of incoming RepositoryID against Local RepositoryID
+// Star the repo if it wasn't already stared
+// Do some mitigation against out of order attacks
+func ProcessLikeActivity(ctx *context_service.APIContext, form any, repositoryID int64) (int, string, error) {
+	activity := form.(*fm.ForgeLike)
+	if res, err := validation.IsValid(activity); !res {
+		return http.StatusNotAcceptable, "Invalid activity", err
+	}
+	log.Trace("Activity validated: %#v", activity)
+
+	// parse actorID (person)
+	actorURI := activity.Actor.GetID().String()
+	user, _, federationHost, err := FindOrCreateFederatedUser(ctx.Base, actorURI)
+	if err != nil {
+		ctx.Error(http.StatusNotAcceptable, "Federated user not found", err)
+		return http.StatusInternalServerError, "FindOrCreateFederatedUser", err
+	}
+
+	if !activity.IsNewer(federationHost.LatestActivity) {
+		return http.StatusNotAcceptable, "Activity out of order.", errors.New("Activity already processed")
+	}
+
+	// parse objectID (repository)
+	objectID, err := fm.NewRepositoryID(activity.Object.GetID().String(), string(forgefed.ForgejoSourceType))
+	if err != nil {
+		return http.StatusNotAcceptable, "Invalid objectId", err
+	}
+	if objectID.ID != fmt.Sprint(repositoryID) {
+		return http.StatusNotAcceptable, "Invalid objectId", err
+	}
+	log.Trace("Object accepted: %#v", objectID)
+
+	// execute the activity if the repo was not stared already
+	alreadyStared := repo.IsStaring(ctx, user.ID, repositoryID)
+	if !alreadyStared {
+		err = repo.StarRepo(ctx, user.ID, repositoryID, true)
+		if err != nil {
+			return http.StatusNotAcceptable, "Error staring", err
+		}
+	}
+	federationHost.LatestActivity = activity.StartTime
+	err = forgefed.UpdateFederationHost(ctx, federationHost)
+	if err != nil {
+		return http.StatusNotAcceptable, "Error updating federatedHost", err
+	}
+
+	return 0, "", nil
+}
+
+// Create or update a list of FollowingRepo structs
+func StoreFollowingRepoList(ctx *context_service.Context, localRepoID int64, followingRepoList []string) (int, string, error) {
+	followingRepos := make([]*repo.FollowingRepo, 0, len(followingRepoList))
+	for _, uri := range followingRepoList {
+		federationHost, err := FindOrCreateFederationHost(ctx.Base, uri)
+		if err != nil {
+			return http.StatusInternalServerError, "Wrong FederationHost", err
+		}
+		followingRepoID, err := fm.NewRepositoryID(uri, string(federationHost.NodeInfo.SoftwareName))
+		if err != nil {
+			return http.StatusNotAcceptable, "Invalid federated repo", err
+		}
+		followingRepo, err := repo.NewFollowingRepo(localRepoID, followingRepoID.ID, federationHost.ID, uri)
+		if err != nil {
+			return http.StatusNotAcceptable, "Invalid federated repo", err
+		}
+		followingRepos = append(followingRepos, &followingRepo)
+	}
+
+	if err := repo.StoreFollowingRepos(ctx, localRepoID, followingRepos); err != nil {
+		return 0, "", err
+	}
+
+	return 0, "", nil
+}
+
+func DeleteFollowingRepos(ctx context.Context, localRepoID int64) error {
+	return repo.StoreFollowingRepos(ctx, localRepoID, []*repo.FollowingRepo{})
+}
+
+func SendLikeActivities(ctx context.Context, doer user.User, repoID int64) error {
+	followingRepos, err := repo.FindFollowingReposByRepoID(ctx, repoID)
+	log.Trace("Federated Repos is: %#v", followingRepos)
+	if err != nil {
+		return err
+	}
+
+	likeActivityList := make([]fm.ForgeLike, 0)
+	for _, followingRepo := range followingRepos {
+		log.Trace("Found following repo: %#v", followingRepo)
+		target := followingRepo.URI
+		likeActivity, err := fm.NewForgeLike(doer.APActorID(), target, time.Now())
+		if err != nil {
+			return err
+		}
+		likeActivityList = append(likeActivityList, likeActivity)
+	}
+
+	apclientFactory, err := activitypub.GetClientFactory(ctx)
+	if err != nil {
+		return err
+	}
+	apclient, err := apclientFactory.WithKeys(ctx, &doer, doer.APActorID()+"#main-key")
+	if err != nil {
+		return err
+	}
+	for i, activity := range likeActivityList {
+		activity.StartTime = activity.StartTime.Add(time.Duration(i) * time.Second)
+		json, err := activity.MarshalJSON()
+		if err != nil {
+			return err
+		}
+
+		_, err = apclient.Post(json, fmt.Sprintf("%v/inbox", activity.Object))
+		if err != nil {
+			log.Error("error %v while sending activity: %#v", err, activity)
+		}
+	}
+
+	return nil
+}

services/federation/signature_service.go

@@ -0,0 +1,234 @@
+// Copyright 2024, 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package federation
+
+import (
+	"crypto/x509"
+	"database/sql"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"net/url"
+
+	"forgejo.org/models/forgefed"
+	"forgejo.org/models/user"
+	"forgejo.org/modules/activitypub"
+	fm "forgejo.org/modules/forgefed"
+	context_service "forgejo.org/services/context"
+
+	ap "github.com/go-ap/activitypub"
+)
+
+// Factory function for ActorID. Created struct is asserted to be valid
+func NewActorIDFromKeyID(ctx *context_service.Base, uri string) (fm.ActorID, error) {
+	parsedURI, err := url.Parse(uri)
+	parsedURI.Fragment = ""
+	if err != nil {
+		return fm.ActorID{}, err
+	}
+
+	actionsUser := user.NewAPServerActor()
+	clientFactory, err := activitypub.GetClientFactory(ctx)
+	if err != nil {
+		return fm.ActorID{}, err
+	}
+
+	apClient, err := clientFactory.WithKeys(ctx, actionsUser, actionsUser.KeyID())
+	if err != nil {
+		return fm.ActorID{}, err
+	}
+
+	userResponse, err := apClient.GetBody(parsedURI.String())
+	if err != nil {
+		return fm.ActorID{}, err
+	}
+
+	var actor ap.Actor
+	err = actor.UnmarshalJSON(userResponse)
+	if err != nil {
+		return fm.ActorID{}, err
+	}
+
+	result, err := fm.NewActorID(actor.PublicKey.Owner.String())
+	return result, err
+}
+
+func FindOrCreateFederatedUserKey(ctx *context_service.Base, keyID string) (pubKey any, err error) {
+	var federatedUser *user.FederatedUser
+	var keyURL *url.URL
+
+	keyURL, err = url.Parse(keyID)
+	if err != nil {
+		return nil, err
+	}
+
+	// Try if the signing actor is an already known federated user
+	_, federatedUser, err = user.FindFederatedUserByKeyID(ctx, keyURL.String())
+	if err != nil {
+		return nil, err
+	}
+
+	if federatedUser == nil {
+		rawActorID, err := NewActorIDFromKeyID(ctx, keyID)
+		if err != nil {
+			return nil, err
+		}
+
+		_, federatedUser, _, err = FindOrCreateFederatedUser(ctx, rawActorID.AsURI())
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		_, err = forgefed.GetFederationHost(ctx, federatedUser.FederationHostID)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if federatedUser.PublicKey.Valid {
+		pubKey, err := x509.ParsePKIXPublicKey(federatedUser.PublicKey.V)
+		if err != nil {
+			return nil, err
+		}
+		return pubKey, nil
+	}
+
+	// Fetch missing public key
+	pubKey, pubKeyBytes, apPerson, err := fetchKeyFromAp(ctx, *keyURL)
+	if err != nil {
+		return nil, err
+	}
+	if apPerson.Type == ap.ActivityVocabularyType("Person") {
+		// Check federatedUser.id = person.id
+		if federatedUser.ExternalID != apPerson.ID.String() {
+			return nil, fmt.Errorf("federated user fetched (%v) does not match the stored one %v", apPerson, federatedUser)
+		}
+		// update federated user
+		federatedUser.KeyID = sql.NullString{
+			String: apPerson.PublicKey.ID.String(),
+			Valid:  true,
+		}
+		federatedUser.PublicKey = sql.Null[sql.RawBytes]{
+			V:     pubKeyBytes,
+			Valid: true,
+		}
+		err = user.UpdateFederatedUser(ctx, federatedUser)
+		if err != nil {
+			return nil, err
+		}
+		return pubKey, nil
+	}
+	return nil, nil
+}
+
+func FindOrCreateFederationHostKey(ctx *context_service.Base, keyID string) (pubKey any, err error) {
+	keyURL, err := url.Parse(keyID)
+	if err != nil {
+		return nil, err
+	}
+	rawActorID, err := NewActorIDFromKeyID(ctx, keyID)
+	if err != nil {
+		return nil, err
+	}
+
+	// Is there an already known federation host?
+	federationHost, err := forgefed.FindFederationHostByKeyID(ctx, keyURL.String())
+	if err != nil {
+		return nil, err
+	}
+
+	if federationHost == nil {
+		federationHost, err = FindOrCreateFederationHost(ctx, rawActorID.AsURI())
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Is there an already an key?
+	if federationHost.PublicKey.Valid {
+		pubKey, err := x509.ParsePKIXPublicKey(federationHost.PublicKey.V)
+		if err != nil {
+			return nil, err
+		}
+		return pubKey, nil
+	}
+
+	// If not, fetch missing public key
+	pubKey, pubKeyBytes, apPerson, err := fetchKeyFromAp(ctx, *keyURL)
+	if err != nil {
+		return nil, err
+	}
+	if apPerson.Type == ap.ActivityVocabularyType("Application") {
+		// Check federationhost.id = person.id
+		if federationHost.HostPort != rawActorID.HostPort || federationHost.HostFqdn != rawActorID.Host ||
+			federationHost.HostSchema != rawActorID.HostSchema {
+			return nil, fmt.Errorf("federation host fetched (%v) does not match the stored one %v", apPerson, federationHost)
+		}
+		// update federation host
+		federationHost.KeyID = sql.NullString{
+			String: apPerson.PublicKey.ID.String(),
+			Valid:  true,
+		}
+		federationHost.PublicKey = sql.Null[sql.RawBytes]{
+			V:     pubKeyBytes,
+			Valid: true,
+		}
+		err = forgefed.UpdateFederationHost(ctx, federationHost)
+		if err != nil {
+			return nil, err
+		}
+		return pubKey, nil
+	}
+	return nil, nil
+}
+
+func fetchKeyFromAp(ctx *context_service.Base, keyURL url.URL) (pubKey any, pubKeyBytes []byte, apPerson *ap.Person, err error) {
+	actionsUser := user.NewAPServerActor()
+	clientFactory, err := activitypub.GetClientFactory(ctx)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	apClient, err := clientFactory.WithKeys(ctx, actionsUser, actionsUser.KeyID())
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	b, err := apClient.GetBody(keyURL.String())
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	person := ap.PersonNew(ap.IRI(keyURL.String()))
+	err = person.UnmarshalJSON(b)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("ActivityStreams type cannot be converted to one known to have publicKey property: %w", err)
+	}
+
+	pubKeyFromAp := person.PublicKey
+	if pubKeyFromAp.ID.String() != keyURL.String() {
+		return nil, nil, nil, fmt.Errorf("cannot find publicKey with id: %v in %v", keyURL, string(b))
+	}
+
+	pubKeyBytes, err = decodePublicKeyPem(pubKeyFromAp.PublicKeyPem)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	pubKey, err = x509.ParsePKIXPublicKey(pubKeyBytes)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	return pubKey, pubKeyBytes, person, err
+}
+
+func decodePublicKeyPem(pubKeyPem string) ([]byte, error) {
+	block, _ := pem.Decode([]byte(pubKeyPem))
+	if block == nil || block.Type != "PUBLIC KEY" {
+		return nil, errors.New("could not decode publicKeyPem to PUBLIC KEY pem block type")
+	}
+
+	return block.Bytes, nil
+}

tests/integration/activitypub_client_test.go

@@ -29,7 +29,7 @@ func TestActivityPubClientBodySize(t *testing.T) {
 		clientFactory, err := activitypub.GetClientFactory(db.DefaultContext)
 		require.NoError(t, err)
 
-		apClient, err := clientFactory.WithKeys(db.DefaultContext, user1, user1.APActorKeyID())
+		apClient, err := clientFactory.WithKeys(db.DefaultContext, user1, user1.KeyID())
 		require.NoError(t, err)
 
 		url := u.JoinPath("/api/v1/nodeinfo").String()

tests/integration/api_activitypub_actor_test.go

@@ -4,12 +4,18 @@
 package integration
 
 import (
+	"fmt"
 	"net/http"
+	"net/url"
+	"strconv"
 	"testing"
 
+	"forgejo.org/modules/forgefed"
 	"forgejo.org/modules/setting"
 	"forgejo.org/modules/test"
 	"forgejo.org/routers"
+	"forgejo.org/services/contexttest"
+	"forgejo.org/services/federation"
 	"forgejo.org/tests"
 
 	ap "github.com/go-ap/activitypub"
@@ -31,10 +37,9 @@ func TestActivityPubActor(t *testing.T) {
 	require.NoError(t, err)
 
 	assert.Equal(t, ap.ApplicationType, actor.Type)
-	assert.Equal(t, setting.Domain, actor.PreferredUsername.String())
+	assert.Equal(t, "ghost", actor.PreferredUsername.String())
 	keyID := actor.GetID().String()
 	assert.Regexp(t, "activitypub/actor$", keyID)
-	assert.Regexp(t, "activitypub/actor/outbox$", actor.Outbox.GetID().String())
 	assert.Regexp(t, "activitypub/actor/inbox$", actor.Inbox.GetID().String())
 
 	pubKey := actor.PublicKey
@@ -46,3 +51,27 @@ func TestActivityPubActor(t *testing.T) {
 	assert.NotNil(t, pubKeyPem)
 	assert.Regexp(t, "^-----BEGIN PUBLIC KEY-----", pubKeyPem)
 }
+
+func TestActorNewFromKeyId(t *testing.T) {
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		ctx, _ := contexttest.MockAPIContext(t, "/api/v1/activitypub/actor")
+		sut, err := federation.NewActorIDFromKeyID(ctx.Base, fmt.Sprintf("%sapi/v1/activitypub/actor#main-key", u))
+		require.NoError(t, err)
+
+		port, err := strconv.ParseUint(u.Port(), 10, 16)
+		require.NoError(t, err)
+
+		assert.Equal(t, forgefed.ActorID{
+			ID:                 "actor",
+			HostSchema:         "http",
+			Path:               "api/v1/activitypub",
+			Host:               setting.Domain,
+			HostPort:           uint16(port),
+			UnvalidatedInput:   fmt.Sprintf("http://%s:%d/api/v1/activitypub/actor", setting.Domain, port),
+			IsPortSupplemented: false,
+		}, sut)
+	})
+}

tests/integration/api_activitypub_person_test.go

@@ -26,28 +26,37 @@ import (
 func TestActivityPubPerson(t *testing.T) {
 	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
 	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
-	onGiteaRun(t, func(t *testing.T, u *url.URL) {
-		userID := 2
-		username := "user2"
-		userURL := fmt.Sprintf("%sapi/v1/activitypub/user-id/%d", u, userID)
 
-		user1 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+	mock := test.NewFederationServerMock()
+	federatedSrv := mock.DistantServer(t)
+	defer federatedSrv.Close()
 
-		clientFactory, err := activitypub.GetClientFactory(db.DefaultContext)
+	onGiteaRun(t, func(t *testing.T, localUrl *url.URL) {
+		defer test.MockVariableValue(&setting.AppURL, localUrl.String())()
+
+		localUserID := 2
+		localUserName := "user2"
+		localUserURL := fmt.Sprintf("%sapi/v1/activitypub/user-id/%d", localUrl, localUserID)
+
+		// distantURL := federatedSrv.URL
+		// distantUser15URL := fmt.Sprintf("%s/api/v1/activitypub/user-id/15", distantURL)
+
+		cf, err := activitypub.GetClientFactory(db.DefaultContext)
 		require.NoError(t, err)
 
-		apClient, err := clientFactory.WithKeys(db.DefaultContext, user1, user1.APActorKeyID())
+		c, err := cf.WithKeysDirect(db.DefaultContext, mock.Persons[0].PrivKey,
+			mock.Persons[0].KeyID(federatedSrv.URL))
 		require.NoError(t, err)
 
 		// Unsigned request
 		t.Run("UnsignedRequest", func(t *testing.T) {
-			req := NewRequest(t, "GET", userURL)
+			req := NewRequest(t, "GET", localUserURL)
 			MakeRequest(t, req, http.StatusBadRequest)
 		})
 
 		t.Run("SignedRequestValidation", func(t *testing.T) {
 			// Signed request
-			resp, err := apClient.GetBody(userURL)
+			resp, err := c.GetBody(localUserURL)
 			require.NoError(t, err)
 
 			var person ap.Person
@@ -55,13 +64,12 @@ func TestActivityPubPerson(t *testing.T) {
 			require.NoError(t, err)
 
 			assert.Equal(t, ap.PersonType, person.Type)
-			assert.Equal(t, username, person.PreferredUsername.String())
-			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d$", userID), person.GetID())
-			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d/outbox$", userID), person.Outbox.GetID().String())
-			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d/inbox$", userID), person.Inbox.GetID().String())
+			assert.Equal(t, localUserName, person.PreferredUsername.String())
+			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d$", localUserID), person.GetID())
+			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d/inbox$", localUserID), person.Inbox.GetID().String())
 
 			assert.NotNil(t, person.PublicKey)
-			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d#main-key$", userID), person.PublicKey.ID)
+			assert.Regexp(t, fmt.Sprintf("activitypub/user-id/%d#main-key$", localUserID), person.PublicKey.ID)
 
 			assert.NotNil(t, person.PublicKey.PublicKeyPem)
 			assert.Regexp(t, "^-----BEGIN PUBLIC KEY-----", person.PublicKey.PublicKeyPem)

tests/integration/api_activitypub_repository_test.go

@@ -29,15 +29,18 @@ func TestActivityPubRepository(t *testing.T) {
 	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
 	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
 
+	mock := test.NewFederationServerMock()
+	federatedSrv := mock.DistantServer(t)
+	defer federatedSrv.Close()
+
 	onGiteaRun(t, func(t *testing.T, u *url.URL) {
 		repositoryID := 2
 
-		apServerActor := user.NewAPServerActor()
-
 		cf, err := activitypub.GetClientFactory(db.DefaultContext)
 		require.NoError(t, err)
 
-		c, err := cf.WithKeys(db.DefaultContext, apServerActor, apServerActor.APActorKeyID())
+		c, err := cf.WithKeysDirect(db.DefaultContext, mock.Persons[0].PrivKey,
+			mock.Persons[0].KeyID(federatedSrv.URL))
 		require.NoError(t, err)
 
 		resp, err := c.GetBody(fmt.Sprintf("%sapi/v1/activitypub/repository-id/%d", u, repositoryID))
@@ -53,9 +56,10 @@ func TestActivityPubRepository(t *testing.T) {
 }
 
 func TestActivityPubMissingRepository(t *testing.T) {
-	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
-	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
 	defer tests.PrepareTestEnv(t)()
+	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&setting.Federation.SignatureEnforced, false)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
 
 	repositoryID := 9999999
 	req := NewRequest(t, "GET", fmt.Sprintf("/api/v1/activitypub/repository-id/%d", repositoryID))
@@ -72,14 +76,14 @@ func TestActivityPubRepositoryInboxValid(t *testing.T) {
 	defer federatedSrv.Close()
 
 	onGiteaRun(t, func(t *testing.T, u *url.URL) {
-		apServerActor := user.NewAPServerActor()
 		repositoryID := 2
 		timeNow := time.Now().UTC()
 
 		cf, err := activitypub.GetClientFactory(db.DefaultContext)
 		require.NoError(t, err)
 
-		c, err := cf.WithKeys(db.DefaultContext, apServerActor, apServerActor.APActorKeyID())
+		c, err := cf.WithKeysDirect(db.DefaultContext, mock.Persons[0].PrivKey,
+			mock.Persons[0].KeyID(federatedSrv.URL))
 		require.NoError(t, err)
 
 		repoInboxURL := u.JoinPath(fmt.Sprintf("/api/v1/activitypub/repository-id/%d/inbox", repositoryID)).String()
@@ -148,6 +152,7 @@ func TestActivityPubRepositoryInboxValid(t *testing.T) {
 
 func TestActivityPubRepositoryInboxInvalid(t *testing.T) {
 	defer test.MockVariableValue(&setting.Federation.Enabled, true)()
+	defer test.MockVariableValue(&setting.Federation.SignatureEnforced, false)()
 	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
 
 	onGiteaRun(t, func(t *testing.T, u *url.URL) {
@@ -157,7 +162,7 @@ func TestActivityPubRepositoryInboxInvalid(t *testing.T) {
 		cf, err := activitypub.GetClientFactory(db.DefaultContext)
 		require.NoError(t, err)
 
-		c, err := cf.WithKeys(db.DefaultContext, apServerActor, apServerActor.APActorKeyID())
+		c, err := cf.WithKeys(db.DefaultContext, apServerActor, apServerActor.KeyID())
 		require.NoError(t, err)
 
 		repoInboxURL := u.JoinPath(fmt.Sprintf("/api/v1/activitypub/repository-id/%d/inbox", repositoryID)).String()

tests/integration/api_federation_httpsig_test.go

@@ -35,7 +35,7 @@ func TestFederationHttpSigValidation(t *testing.T) {
 		clientFactory, err := activitypub.GetClientFactory(db.DefaultContext)
 		require.NoError(t, err)
 
-		apClient, err := clientFactory.WithKeys(db.DefaultContext, user1, user1.APActorKeyID())
+		apClient, err := clientFactory.WithKeys(db.DefaultContext, user1, user1.KeyID())
 		require.NoError(t, err)
 
 		// Unsigned request

tests/integration/webfinger_test.go

@@ -52,6 +52,15 @@ func TestWebfinger(t *testing.T) {
 	assert.Equal(t, "acct:user2@"+appURL.Host, jrd.Subject)
 	assert.ElementsMatch(t, []string{user.HTMLURL(), appURL.String() + "api/v1/activitypub/user-id/" + fmt.Sprint(user.ID)}, jrd.Aliases)
 
+	instanceReq := NewRequest(t, "GET", fmt.Sprintf("/.well-known/webfinger?resource=acct:ghost@%s", appURL.Host))
+	instanceResp := MakeRequest(t, instanceReq, http.StatusOK)
+	assert.Equal(t, "application/jrd+json", instanceResp.Header().Get("Content-Type"))
+
+	var instanceActor webfingerJRD
+	DecodeJSON(t, instanceResp, &instanceActor)
+	assert.Equal(t, "acct:ghost@"+appURL.Host, instanceActor.Subject)
+	assert.ElementsMatch(t, []string{appURL.String() + "api/v1/activitypub/actor"}, instanceActor.Aliases)
+
 	req = NewRequest(t, "GET", fmt.Sprintf("/.well-known/webfinger?resource=acct:%s@%s", user.LowerName, "unknown.host"))
 	MakeRequest(t, req, http.StatusBadRequest)