diff --git a/keyserver/storage/postgres/cross_signing_keys_table.go b/keyserver/storage/postgres/cross_signing_keys_table.go
new file mode 100644
index 00000000..87d0511b
--- /dev/null
+++ b/keyserver/storage/postgres/cross_signing_keys_table.go
@@ -0,0 +1,47 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// 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 postgres
+
+import (
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/keyserver/storage/tables"
+)
+
+var crossSigningKeysSchema = `
+CREATE TABLE IF NOT EXISTS keyserver_cross_signing_keys (
+    user_id TEXT NOT NULL,
+	key_type TEXT NOT NULL,
+	key_data TEXT NOT NULL,
+	stream_id BIGINT NOT NULL 
+);
+
+CREATE UNIQUE INDEX keyserver_cross_signing_keys_idx ON keyserver_cross_signing_keys(user_id, key_type, stream_id);
+`
+
+type crossSigningKeysStatements struct {
+	db *sql.DB
+}
+
+func NewPostgresCrossSigningKeysTable(db *sql.DB) (tables.CrossSigningKeys, error) {
+	s := &crossSigningKeysStatements{
+		db: db,
+	}
+	_, err := db.Exec(crossSigningKeysSchema)
+	if err != nil {
+		return nil, err
+	}
+	return s, nil
+}
diff --git a/keyserver/storage/postgres/cross_signing_sigs_table.go b/keyserver/storage/postgres/cross_signing_sigs_table.go
new file mode 100644
index 00000000..bd0f5862
--- /dev/null
+++ b/keyserver/storage/postgres/cross_signing_sigs_table.go
@@ -0,0 +1,48 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// 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 postgres
+
+import (
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/keyserver/storage/tables"
+)
+
+var crossSigningSigsSchema = `
+CREATE TABLE IF NOT EXISTS keyserver_cross_signing_sigs (
+    user_id TEXT NOT NULL,
+	key_id TEXT NOT NULL,
+	target_user_id TEXT NOT NULL,
+	target_device_id TEXT NOT NULL,
+	signature TEXT NOT NULL 
+);
+
+CREATE UNIQUE INDEX keyserver_cross_signing_sigs_idx ON keyserver_cross_signing_sigs(user_id, target_user_id, target_device_id);
+`
+
+type crossSigningSigsStatements struct {
+	db *sql.DB
+}
+
+func NewPostgresCrossSigningSigsTable(db *sql.DB) (tables.CrossSigningSigs, error) {
+	s := &crossSigningSigsStatements{
+		db: db,
+	}
+	_, err := db.Exec(crossSigningSigsSchema)
+	if err != nil {
+		return nil, err
+	}
+	return s, nil
+}
diff --git a/keyserver/storage/postgres/cross_signing_streams_table.go b/keyserver/storage/postgres/cross_signing_streams_table.go
new file mode 100644
index 00000000..e823a5f3
--- /dev/null
+++ b/keyserver/storage/postgres/cross_signing_streams_table.go
@@ -0,0 +1,45 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// 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 postgres
+
+import (
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/keyserver/storage/tables"
+)
+
+var crossSigningStreamsSchema = `
+CREATE TABLE IF NOT EXISTS keyserver_cross_signing_streams (
+    stream_id BIGINT NOT NULL,
+	from_user_id TEXT NOT NULL,
+	user_ids TEXT NOT NULL,
+	PRIMARY KEY(stream_id)
+);
+`
+
+type crossSigningStreamsStatements struct {
+	db *sql.DB
+}
+
+func NewPostgresCrossSigningStreamsTable(db *sql.DB) (tables.CrossSigningStreams, error) {
+	s := &crossSigningStreamsStatements{
+		db: db,
+	}
+	_, err := db.Exec(crossSigningStreamsSchema)
+	if err != nil {
+		return nil, err
+	}
+	return s, nil
+}
diff --git a/keyserver/storage/postgres/storage.go b/keyserver/storage/postgres/storage.go
index cb16ffaa..fc3575af 100644
--- a/keyserver/storage/postgres/storage.go
+++ b/keyserver/storage/postgres/storage.go
@@ -43,12 +43,27 @@ func NewDatabase(dbProperties *config.DatabaseOptions) (*shared.Database, error)
 	if err != nil {
 		return nil, err
 	}
+	csk, err := NewPostgresCrossSigningKeysTable(db)
+	if err != nil {
+		return nil, err
+	}
+	css, err := NewPostgresCrossSigningSigsTable(db)
+	if err != nil {
+		return nil, err
+	}
+	cst, err := NewPostgresCrossSigningStreamsTable(db)
+	if err != nil {
+		return nil, err
+	}
 	return &shared.Database{
-		DB:                    db,
-		Writer:                sqlutil.NewDummyWriter(),
-		OneTimeKeysTable:      otk,
-		DeviceKeysTable:       dk,
-		KeyChangesTable:       kc,
-		StaleDeviceListsTable: sdl,
+		DB:                       db,
+		Writer:                   sqlutil.NewDummyWriter(),
+		OneTimeKeysTable:         otk,
+		DeviceKeysTable:          dk,
+		KeyChangesTable:          kc,
+		StaleDeviceListsTable:    sdl,
+		CrossSigningKeysTable:    csk,
+		CrossSigningSigsTable:    css,
+		CrossSigningStreamsTable: cst,
 	}, nil
 }
diff --git a/keyserver/storage/shared/storage.go b/keyserver/storage/shared/storage.go
index de757f29..5d76570f 100644
--- a/keyserver/storage/shared/storage.go
+++ b/keyserver/storage/shared/storage.go
@@ -26,12 +26,15 @@ import (
 )
 
 type Database struct {
-	DB                    *sql.DB
-	Writer                sqlutil.Writer
-	OneTimeKeysTable      tables.OneTimeKeys
-	DeviceKeysTable       tables.DeviceKeys
-	KeyChangesTable       tables.KeyChanges
-	StaleDeviceListsTable tables.StaleDeviceLists
+	DB                       *sql.DB
+	Writer                   sqlutil.Writer
+	OneTimeKeysTable         tables.OneTimeKeys
+	DeviceKeysTable          tables.DeviceKeys
+	KeyChangesTable          tables.KeyChanges
+	StaleDeviceListsTable    tables.StaleDeviceLists
+	CrossSigningKeysTable    tables.CrossSigningKeys
+	CrossSigningSigsTable    tables.CrossSigningSigs
+	CrossSigningStreamsTable tables.CrossSigningStreams
 }
 
 func (d *Database) ExistingOneTimeKeys(ctx context.Context, userID, deviceID string, keyIDsWithAlgorithms []string) (map[string]json.RawMessage, error) {
diff --git a/keyserver/storage/sqlite3/cross_signing_keys_table.go b/keyserver/storage/sqlite3/cross_signing_keys_table.go
new file mode 100644
index 00000000..81de19a9
--- /dev/null
+++ b/keyserver/storage/sqlite3/cross_signing_keys_table.go
@@ -0,0 +1,47 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// 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 sqlite3
+
+import (
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/keyserver/storage/tables"
+)
+
+var crossSigningKeysSchema = `
+CREATE TABLE IF NOT EXISTS keyserver_cross_signing_keys (
+    user_id TEXT NOT NULL,
+	key_type TEXT NOT NULL,
+	key_data TEXT NOT NULL,
+	stream_id BIGINT NOT NULL 
+);
+
+CREATE UNIQUE INDEX keyserver_cross_signing_keys_idx ON keyserver_cross_signing_keys(user_id, key_type, stream_id);
+`
+
+type crossSigningKeysStatements struct {
+	db *sql.DB
+}
+
+func NewSqliteCrossSigningKeysTable(db *sql.DB) (tables.CrossSigningKeys, error) {
+	s := &crossSigningKeysStatements{
+		db: db,
+	}
+	_, err := db.Exec(crossSigningKeysSchema)
+	if err != nil {
+		return nil, err
+	}
+	return s, nil
+}
diff --git a/keyserver/storage/sqlite3/cross_signing_sigs_table.go b/keyserver/storage/sqlite3/cross_signing_sigs_table.go
new file mode 100644
index 00000000..f6a4bc06
--- /dev/null
+++ b/keyserver/storage/sqlite3/cross_signing_sigs_table.go
@@ -0,0 +1,48 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// 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 sqlite3
+
+import (
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/keyserver/storage/tables"
+)
+
+var crossSigningSigsSchema = `
+CREATE TABLE IF NOT EXISTS keyserver_cross_signing_sigs (
+    user_id TEXT NOT NULL,
+	key_id TEXT NOT NULL,
+	target_user_id TEXT NOT NULL,
+	target_device_id TEXT NOT NULL,
+	signature TEXT NOT NULL 
+);
+
+CREATE UNIQUE INDEX keyserver_cross_signing_sigs_idx ON keyserver_cross_signing_sigs(user_id, target_user_id, target_device_id);
+`
+
+type crossSigningSigsStatements struct {
+	db *sql.DB
+}
+
+func NewSqliteCrossSigningSigsTable(db *sql.DB) (tables.CrossSigningSigs, error) {
+	s := &crossSigningSigsStatements{
+		db: db,
+	}
+	_, err := db.Exec(crossSigningSigsSchema)
+	if err != nil {
+		return nil, err
+	}
+	return s, nil
+}
diff --git a/keyserver/storage/sqlite3/cross_signing_streams_table.go b/keyserver/storage/sqlite3/cross_signing_streams_table.go
new file mode 100644
index 00000000..ecd54e32
--- /dev/null
+++ b/keyserver/storage/sqlite3/cross_signing_streams_table.go
@@ -0,0 +1,45 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// 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 sqlite3
+
+import (
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/keyserver/storage/tables"
+)
+
+var crossSigningStreamsSchema = `
+CREATE TABLE IF NOT EXISTS keyserver_cross_signing_streams (
+    stream_id BIGINT NOT NULL,
+	from_user_id TEXT NOT NULL,
+	user_ids TEXT NOT NULL,
+	PRIMARY KEY(stream_id)
+);
+`
+
+type crossSigningStreamsStatements struct {
+	db *sql.DB
+}
+
+func NewSqliteCrossSigningStreamsTable(db *sql.DB) (tables.CrossSigningStreams, error) {
+	s := &crossSigningStreamsStatements{
+		db: db,
+	}
+	_, err := db.Exec(crossSigningStreamsSchema)
+	if err != nil {
+		return nil, err
+	}
+	return s, nil
+}
diff --git a/keyserver/storage/sqlite3/storage.go b/keyserver/storage/sqlite3/storage.go
index ca1e7560..dbbd8da1 100644
--- a/keyserver/storage/sqlite3/storage.go
+++ b/keyserver/storage/sqlite3/storage.go
@@ -41,12 +41,27 @@ func NewDatabase(dbProperties *config.DatabaseOptions) (*shared.Database, error)
 	if err != nil {
 		return nil, err
 	}
+	csk, err := NewSqliteCrossSigningKeysTable(db)
+	if err != nil {
+		return nil, err
+	}
+	css, err := NewSqliteCrossSigningSigsTable(db)
+	if err != nil {
+		return nil, err
+	}
+	cst, err := NewSqliteCrossSigningStreamsTable(db)
+	if err != nil {
+		return nil, err
+	}
 	return &shared.Database{
-		DB:                    db,
-		Writer:                sqlutil.NewExclusiveWriter(),
-		OneTimeKeysTable:      otk,
-		DeviceKeysTable:       dk,
-		KeyChangesTable:       kc,
-		StaleDeviceListsTable: sdl,
+		DB:                       db,
+		Writer:                   sqlutil.NewExclusiveWriter(),
+		OneTimeKeysTable:         otk,
+		DeviceKeysTable:          dk,
+		KeyChangesTable:          kc,
+		StaleDeviceListsTable:    sdl,
+		CrossSigningKeysTable:    csk,
+		CrossSigningSigsTable:    css,
+		CrossSigningStreamsTable: cst,
 	}, nil
 }
diff --git a/keyserver/storage/tables/interface.go b/keyserver/storage/tables/interface.go
index b70c9bce..338d4a73 100644
--- a/keyserver/storage/tables/interface.go
+++ b/keyserver/storage/tables/interface.go
@@ -52,3 +52,9 @@ type StaleDeviceLists interface {
 	InsertStaleDeviceList(ctx context.Context, userID string, isStale bool) error
 	SelectUserIDsWithStaleDeviceLists(ctx context.Context, domains []gomatrixserverlib.ServerName) ([]string, error)
 }
+
+type CrossSigningKeys interface{}
+
+type CrossSigningSigs interface{}
+
+type CrossSigningStreams interface{}