333 lines
13 KiB
Go
333 lines
13 KiB
Go
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// Copyright (c) 2020 Nikos Filippakis
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at http://mozilla.org/MPL/2.0/.
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package crypto
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import (
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"encoding/json"
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"errors"
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"time"
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"maunium.net/go/mautrix/crypto/canonicaljson"
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"maunium.net/go/mautrix/crypto/olm"
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"maunium.net/go/mautrix/event"
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"maunium.net/go/mautrix/id"
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)
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var (
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ErrNoVerificationFromDevice = errors.New("from_device field is empty")
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ErrNoVerificationMethods = errors.New("verification method list is empty")
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ErrNoRelatesTo = errors.New("missing m.relates_to info")
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)
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// ProcessInRoomVerification is a callback that is to be called when a client receives a message
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// related to in-room verification.
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//
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// Currently this is not automatically called, so you must add the listener yourself.
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// Note that in-room verification events are wrapped in m.room.encrypted, but this expects the decrypted events.
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func (mach *OlmMachine) ProcessInRoomVerification(evt *event.Event) error {
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if evt.Sender == mach.Client.UserID {
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// nothing to do if the message is our own
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return nil
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}
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if relatable, ok := evt.Content.Parsed.(event.Relatable); !ok || relatable.OptionalGetRelatesTo() == nil {
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return ErrNoRelatesTo
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}
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switch content := evt.Content.Parsed.(type) {
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case *event.MessageEventContent:
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if content.MsgType == event.MsgVerificationRequest {
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if content.FromDevice == "" {
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return ErrNoVerificationFromDevice
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}
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if content.Methods == nil {
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return ErrNoVerificationMethods
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}
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newContent := &event.VerificationRequestEventContent{
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FromDevice: content.FromDevice,
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Methods: content.Methods,
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Timestamp: evt.Timestamp,
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TransactionID: evt.ID.String(),
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}
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mach.handleVerificationRequest(evt.Sender, newContent, evt.ID.String(), evt.RoomID)
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}
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case *event.VerificationStartEventContent:
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mach.handleVerificationStart(evt.Sender, content, content.RelatesTo.EventID.String(), 10*time.Minute, evt.RoomID)
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case *event.VerificationReadyEventContent:
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mach.handleInRoomVerificationReady(evt.Sender, evt.RoomID, content, content.RelatesTo.EventID.String())
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case *event.VerificationAcceptEventContent:
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mach.handleVerificationAccept(evt.Sender, content, content.RelatesTo.EventID.String())
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case *event.VerificationKeyEventContent:
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mach.handleVerificationKey(evt.Sender, content, content.RelatesTo.EventID.String())
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case *event.VerificationMacEventContent:
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mach.handleVerificationMAC(evt.Sender, content, content.RelatesTo.EventID.String())
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case *event.VerificationCancelEventContent:
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mach.handleVerificationCancel(evt.Sender, content, content.RelatesTo.EventID.String())
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}
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return nil
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}
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// SendInRoomSASVerificationCancel is used to manually send an in-room SAS cancel message process with the given reason and cancellation code.
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func (mach *OlmMachine) SendInRoomSASVerificationCancel(roomID id.RoomID, userID id.UserID, transactionID string, reason string, code event.VerificationCancelCode) error {
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content := &event.VerificationCancelEventContent{
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RelatesTo: &event.RelatesTo{Type: event.RelReference, EventID: id.EventID(transactionID)},
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Reason: reason,
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Code: code,
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To: userID,
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}
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encrypted, err := mach.EncryptMegolmEvent(roomID, event.InRoomVerificationCancel, content)
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if err != nil {
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return err
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}
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_, err = mach.Client.SendMessageEvent(roomID, event.EventEncrypted, encrypted)
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return err
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}
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// SendInRoomSASVerificationRequest is used to manually send an in-room SAS verification request message to another user.
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func (mach *OlmMachine) SendInRoomSASVerificationRequest(roomID id.RoomID, toUserID id.UserID, methods []VerificationMethod) (string, error) {
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content := &event.MessageEventContent{
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MsgType: event.MsgVerificationRequest,
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FromDevice: mach.Client.DeviceID,
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Methods: []event.VerificationMethod{event.VerificationMethodSAS},
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To: toUserID,
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}
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encrypted, err := mach.EncryptMegolmEvent(roomID, event.EventMessage, content)
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if err != nil {
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return "", err
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}
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resp, err := mach.Client.SendMessageEvent(roomID, event.EventEncrypted, encrypted)
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if err != nil {
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return "", err
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}
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return resp.EventID.String(), nil
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}
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// SendInRoomSASVerificationReady is used to manually send an in-room SAS verification ready message to another user.
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func (mach *OlmMachine) SendInRoomSASVerificationReady(roomID id.RoomID, transactionID string) error {
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content := &event.VerificationReadyEventContent{
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FromDevice: mach.Client.DeviceID,
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Methods: []event.VerificationMethod{event.VerificationMethodSAS},
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RelatesTo: &event.RelatesTo{Type: event.RelReference, EventID: id.EventID(transactionID)},
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}
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encrypted, err := mach.EncryptMegolmEvent(roomID, event.InRoomVerificationReady, content)
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if err != nil {
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return err
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}
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_, err = mach.Client.SendMessageEvent(roomID, event.EventEncrypted, encrypted)
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return err
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}
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// SendInRoomSASVerificationStart is used to manually send the in-room SAS verification start message to another user.
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func (mach *OlmMachine) SendInRoomSASVerificationStart(roomID id.RoomID, toUserID id.UserID, transactionID string, methods []VerificationMethod) (*event.VerificationStartEventContent, error) {
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sasMethods := make([]event.SASMethod, len(methods))
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for i, method := range methods {
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sasMethods[i] = method.Type()
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}
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content := &event.VerificationStartEventContent{
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FromDevice: mach.Client.DeviceID,
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RelatesTo: &event.RelatesTo{Type: event.RelReference, EventID: id.EventID(transactionID)},
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Method: event.VerificationMethodSAS,
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KeyAgreementProtocols: []event.KeyAgreementProtocol{event.KeyAgreementCurve25519HKDFSHA256},
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Hashes: []event.VerificationHashMethod{event.VerificationHashSHA256},
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MessageAuthenticationCodes: []event.MACMethod{event.HKDFHMACSHA256},
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ShortAuthenticationString: sasMethods,
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To: toUserID,
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}
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encrypted, err := mach.EncryptMegolmEvent(roomID, event.InRoomVerificationStart, content)
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if err != nil {
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return nil, err
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}
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_, err = mach.Client.SendMessageEvent(roomID, event.EventEncrypted, encrypted)
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return content, err
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}
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// SendInRoomSASVerificationAccept is used to manually send an accept for an in-room SAS verification process from a received m.key.verification.start event.
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func (mach *OlmMachine) SendInRoomSASVerificationAccept(roomID id.RoomID, fromUser id.UserID, startEvent *event.VerificationStartEventContent, transactionID string, publicKey []byte, methods []VerificationMethod) error {
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if startEvent.Method != event.VerificationMethodSAS {
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reason := "Unknown verification method: " + string(startEvent.Method)
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if err := mach.SendInRoomSASVerificationCancel(roomID, fromUser, transactionID, reason, event.VerificationCancelUnknownMethod); err != nil {
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return err
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}
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return ErrUnknownVerificationMethod
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}
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payload, err := json.Marshal(startEvent)
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if err != nil {
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return err
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}
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canonical, err := canonicaljson.CanonicalJSON(payload)
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if err != nil {
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return err
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}
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hash := olm.NewUtility().Sha256(string(publicKey) + string(canonical))
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sasMethods := make([]event.SASMethod, len(methods))
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for i, method := range methods {
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sasMethods[i] = method.Type()
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}
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content := &event.VerificationAcceptEventContent{
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RelatesTo: &event.RelatesTo{Type: event.RelReference, EventID: id.EventID(transactionID)},
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Method: event.VerificationMethodSAS,
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KeyAgreementProtocol: event.KeyAgreementCurve25519HKDFSHA256,
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Hash: event.VerificationHashSHA256,
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MessageAuthenticationCode: event.HKDFHMACSHA256,
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ShortAuthenticationString: sasMethods,
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Commitment: hash,
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To: fromUser,
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}
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encrypted, err := mach.EncryptMegolmEvent(roomID, event.InRoomVerificationAccept, content)
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if err != nil {
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return err
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}
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_, err = mach.Client.SendMessageEvent(roomID, event.EventEncrypted, encrypted)
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return err
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}
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// SendInRoomSASVerificationKey sends the ephemeral public key for a device to the partner device for an in-room verification.
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func (mach *OlmMachine) SendInRoomSASVerificationKey(roomID id.RoomID, userID id.UserID, transactionID string, key string) error {
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content := &event.VerificationKeyEventContent{
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RelatesTo: &event.RelatesTo{Type: event.RelReference, EventID: id.EventID(transactionID)},
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Key: key,
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To: userID,
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}
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encrypted, err := mach.EncryptMegolmEvent(roomID, event.InRoomVerificationKey, content)
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if err != nil {
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return err
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}
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_, err = mach.Client.SendMessageEvent(roomID, event.EventEncrypted, encrypted)
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return err
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}
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// SendInRoomSASVerificationMAC sends the MAC of a device's key to the partner device for an in-room verification.
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func (mach *OlmMachine) SendInRoomSASVerificationMAC(roomID id.RoomID, userID id.UserID, deviceID id.DeviceID, transactionID string, sas *olm.SAS) error {
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keyID := id.NewKeyID(id.KeyAlgorithmEd25519, mach.Client.DeviceID.String())
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signingKey := mach.account.SigningKey()
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keyIDsMap := map[id.KeyID]string{keyID: ""}
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macMap := make(map[id.KeyID]string)
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if mach.CrossSigningKeys != nil {
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masterKey := mach.CrossSigningKeys.MasterKey.PublicKey
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masterKeyID := id.NewKeyID(id.KeyAlgorithmEd25519, masterKey.String())
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// add master key ID to key map
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keyIDsMap[masterKeyID] = ""
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masterKeyMAC, _, err := mach.getPKAndKeysMAC(sas, mach.Client.UserID, mach.Client.DeviceID,
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userID, deviceID, transactionID, masterKey, masterKeyID, keyIDsMap)
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if err != nil {
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mach.Log.Error("Error generating master key MAC: %v", err)
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} else {
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mach.Log.Debug("Generated master key `%v` MAC: %v", masterKey, masterKeyMAC)
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macMap[masterKeyID] = masterKeyMAC
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}
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}
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pubKeyMac, keysMac, err := mach.getPKAndKeysMAC(sas, mach.Client.UserID, mach.Client.DeviceID, userID, deviceID, transactionID, signingKey, keyID, keyIDsMap)
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if err != nil {
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return err
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}
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mach.Log.Debug("MAC of key %s is: %s", signingKey, pubKeyMac)
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mach.Log.Debug("MAC of key ID(s) %s is: %s", keyID, keysMac)
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macMap[keyID] = pubKeyMac
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content := &event.VerificationMacEventContent{
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RelatesTo: &event.RelatesTo{Type: event.RelReference, EventID: id.EventID(transactionID)},
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Keys: keysMac,
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Mac: macMap,
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To: userID,
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}
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encrypted, err := mach.EncryptMegolmEvent(roomID, event.InRoomVerificationMAC, content)
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if err != nil {
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return err
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}
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_, err = mach.Client.SendMessageEvent(roomID, event.EventEncrypted, encrypted)
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return err
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}
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// NewInRoomSASVerificationWith starts the in-room SAS verification process with another user in the given room.
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// It returns the generated transaction ID.
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func (mach *OlmMachine) NewInRoomSASVerificationWith(inRoomID id.RoomID, userID id.UserID, hooks VerificationHooks, timeout time.Duration) (string, error) {
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return mach.newInRoomSASVerificationWithInner(inRoomID, &DeviceIdentity{UserID: userID}, hooks, "", timeout)
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}
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func (mach *OlmMachine) newInRoomSASVerificationWithInner(inRoomID id.RoomID, device *DeviceIdentity, hooks VerificationHooks, transactionID string, timeout time.Duration) (string, error) {
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mach.Log.Debug("Starting new in-room verification transaction user %v", device.UserID)
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request := transactionID == ""
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if request {
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var err error
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// get new transaction ID from the request message event ID
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transactionID, err = mach.SendInRoomSASVerificationRequest(inRoomID, device.UserID, hooks.VerificationMethods())
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if err != nil {
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return "", err
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}
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}
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verState := &verificationState{
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sas: olm.NewSAS(),
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otherDevice: device,
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initiatedByUs: true,
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verificationStarted: false,
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keyReceived: false,
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sasMatched: make(chan bool, 1),
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hooks: hooks,
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inRoomID: inRoomID,
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}
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verState.lock.Lock()
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defer verState.lock.Unlock()
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if !request {
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// start in-room verification
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startEvent, err := mach.SendInRoomSASVerificationStart(inRoomID, device.UserID, transactionID, hooks.VerificationMethods())
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if err != nil {
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return "", err
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}
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payload, err := json.Marshal(startEvent)
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if err != nil {
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return "", err
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}
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canonical, err := canonicaljson.CanonicalJSON(payload)
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if err != nil {
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return "", err
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}
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verState.startEventCanonical = string(canonical)
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}
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mach.keyVerificationTransactionState.Store(device.UserID.String()+":"+transactionID, verState)
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mach.timeoutAfter(verState, transactionID, timeout)
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return transactionID, nil
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}
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func (mach *OlmMachine) handleInRoomVerificationReady(userID id.UserID, roomID id.RoomID, content *event.VerificationReadyEventContent, transactionID string) {
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device, err := mach.GetOrFetchDevice(userID, content.FromDevice)
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if err != nil {
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mach.Log.Error("Error fetching device %v of user %v: %v", content.FromDevice, userID, err)
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return
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}
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verState, err := mach.getTransactionState(transactionID, userID)
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if err != nil {
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mach.Log.Error("Error getting transaction state: %v", err)
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return
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}
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//mach.keyVerificationTransactionState.Delete(userID.String() + ":" + transactionID)
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if mach.Client.UserID < userID {
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// up to us to send the start message
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verState.lock.Lock()
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mach.newInRoomSASVerificationWithInner(roomID, device, verState.hooks, transactionID, 10*time.Minute)
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verState.lock.Unlock()
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}
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}
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