120 lines
4.1 KiB
Go
120 lines
4.1 KiB
Go
// 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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"fmt"
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"maunium.net/go/mautrix"
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"maunium.net/go/mautrix/crypto/ssss"
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"maunium.net/go/mautrix/crypto/utils"
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"maunium.net/go/mautrix/event"
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)
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// FetchCrossSigningKeysFromSSSS fetches all the cross-signing keys from SSSS, decrypts them using the given key and stores them in the olm machine.
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func (mach *OlmMachine) FetchCrossSigningKeysFromSSSS(key *ssss.Key) error {
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masterKey, err := mach.retrieveDecryptXSigningKey(event.AccountDataCrossSigningMaster, key)
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if err != nil {
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return err
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}
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selfSignKey, err := mach.retrieveDecryptXSigningKey(event.AccountDataCrossSigningSelf, key)
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if err != nil {
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return err
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}
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userSignKey, err := mach.retrieveDecryptXSigningKey(event.AccountDataCrossSigningUser, key)
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if err != nil {
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return err
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}
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return mach.ImportCrossSigningKeys(CrossSigningSeeds{
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MasterKey: masterKey[:],
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SelfSigningKey: selfSignKey[:],
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UserSigningKey: userSignKey[:],
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})
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}
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// retrieveDecryptXSigningKey retrieves the requested cross-signing key from SSSS and decrypts it using the given SSSS key.
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func (mach *OlmMachine) retrieveDecryptXSigningKey(keyName event.Type, key *ssss.Key) ([utils.AESCTRKeyLength]byte, error) {
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var decryptedKey [utils.AESCTRKeyLength]byte
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var encData ssss.EncryptedAccountDataEventContent
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// retrieve and parse the account data for this key type from SSSS
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err := mach.Client.GetAccountData(keyName.Type, &encData)
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if err != nil {
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return decryptedKey, err
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}
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decrypted, err := encData.Decrypt(keyName.Type, key)
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if err != nil {
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return decryptedKey, err
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}
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copy(decryptedKey[:], decrypted)
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return decryptedKey, nil
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}
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// GenerateAndUploadCrossSigningKeys generates a new key with all corresponding cross-signing keys.
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//
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// A passphrase can be provided to generate the SSSS key. If the passphrase is empty, a random key
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// is used. The base58-formatted recovery key is the first return parameter.
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//
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// The account password of the user is required for uploading keys to the server.
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func (mach *OlmMachine) GenerateAndUploadCrossSigningKeys(userPassword, passphrase string) (string, error) {
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key, err := mach.SSSS.GenerateAndUploadKey(passphrase)
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if err != nil {
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return "", fmt.Errorf("failed to generate and upload SSSS key: %w", err)
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}
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// generate the three cross-signing keys
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keysCache, err := mach.GenerateCrossSigningKeys()
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if err != nil {
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return "", err
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}
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recoveryKey := key.RecoveryKey()
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// Store the private keys in SSSS
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if err := mach.UploadCrossSigningKeysToSSSS(key, keysCache); err != nil {
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return recoveryKey, fmt.Errorf("failed to upload cross-signing keys to SSSS: %w", err)
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}
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// Publish cross-signing keys
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err = mach.PublishCrossSigningKeys(keysCache, func(uiResp *mautrix.RespUserInteractive) interface{} {
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return &mautrix.ReqUIAuthLogin{
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BaseAuthData: mautrix.BaseAuthData{
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Type: mautrix.AuthTypePassword,
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Session: uiResp.Session,
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},
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User: mach.Client.UserID.String(),
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Password: userPassword,
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}
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})
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if err != nil {
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return recoveryKey, fmt.Errorf("failed to publish cross-signing keys: %w", err)
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}
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err = mach.SSSS.SetDefaultKeyID(key.ID)
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if err != nil {
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return recoveryKey, fmt.Errorf("failed to mark %s as the default key: %w", key.ID, err)
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}
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return recoveryKey, nil
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}
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// UploadCrossSigningKeysToSSSS stores the given cross-signing keys on the server encrypted with the given key.
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func (mach *OlmMachine) UploadCrossSigningKeysToSSSS(key *ssss.Key, keys *CrossSigningKeysCache) error {
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if err := mach.SSSS.SetEncryptedAccountData(event.AccountDataCrossSigningMaster, keys.MasterKey.Seed, key); err != nil {
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return err
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}
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if err := mach.SSSS.SetEncryptedAccountData(event.AccountDataCrossSigningSelf, keys.SelfSigningKey.Seed, key); err != nil {
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return err
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}
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if err := mach.SSSS.SetEncryptedAccountData(event.AccountDataCrossSigningUser, keys.UserSigningKey.Seed, key); err != nil {
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return err
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}
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return nil
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}
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