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move curve25519 code to separate file

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This commit is contained in:
Bruno Windels 2022-01-26 10:13:01 +01:00
parent 86caa5f9b1
commit cfb94206f9
2 changed files with 113 additions and 91 deletions
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89
src/matrix/e2ee/megolm/keybackup/Curve25519.ts Normal file
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@ -0,0 +1,89 @@
/*
Copyright 2022 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.
*/
import {MEGOLM_ALGORITHM} from "../../common";
import type {RoomKey} from "../decryption/RoomKey";
import type {BaseBackupInfo, SignatureMap, SessionKeyInfo} from "./KeyBackup";
import type * as OlmNamespace from "@matrix-org/olm";
type Olm = typeof OlmNamespace;
export const Algorithm = "m.megolm_backup.v1.curve25519-aes-sha2";
export type BackupInfo = BaseBackupInfo & {
algorithm: typeof Algorithm,
auth_data: AuthData,
}
export type AuthData = {
public_key: string,
signatures: SignatureMap
}
export type SessionData = {
ciphertext: string,
mac: string,
ephemeral: string,
}
export class BackupEncryption {
constructor(
private readonly encryption: Olm.PkEncryption,
private readonly decryption: Olm.PkDecryption
) {}
static fromAuthData(authData: AuthData, privateKey: Uint8Array, olm: Olm): BackupEncryption {
const expectedPubKey = authData.public_key;
const decryption = new olm.PkDecryption();
const encryption = new olm.PkEncryption();
try {
const pubKey = decryption.init_with_private_key(privateKey);
if (pubKey !== expectedPubKey) {
throw new Error(`Bad backup key, public key does not match. Calculated ${pubKey} but expected ${expectedPubKey}`);
}
encryption.set_recipient_key(pubKey);
} catch(err) {
decryption.free();
throw err;
}
return new BackupEncryption(encryption, decryption);
}
decryptRoomKey(sessionData: SessionData): SessionKeyInfo {
const sessionInfo = this.decryption.decrypt(
sessionData.ephemeral,
sessionData.mac,
sessionData.ciphertext,
);
return JSON.parse(sessionInfo) as SessionKeyInfo;
}
encryptRoomKey(key: RoomKey, sessionKey: string): SessionData {
const sessionInfo: SessionKeyInfo = {
algorithm: MEGOLM_ALGORITHM,
sender_key: key.senderKey,
sender_claimed_keys: {ed25519: key.claimedEd25519Key},
forwarding_curve25519_key_chain: [],
session_key: sessionKey
};
return this.encryption.encrypt(JSON.stringify(sessionInfo)) as SessionData;
}
dispose() {
this.decryption.free();
this.encryption.free();
}
}

115
src/matrix/e2ee/megolm/keybackup/KeyBackup.ts
View file

@ -15,9 +15,9 @@ limitations under the License.
*/
import {StoreNames} from "../../../storage/common";
import {LRUCache} from "../../../../utils/LRUCache";
import {keyFromStorage, keyFromBackup} from "../decryption/RoomKey";
import {MEGOLM_ALGORITHM} from "../../common";
import * as Curve25519 from "./Curve25519";
import type {HomeServerApi} from "../../../net/HomeServerApi";
import type {IncomingRoomKey, RoomKey} from "../decryption/RoomKey";
@ -31,48 +31,28 @@ import type {Transaction} from "../../../storage/idb/Transaction";
import type * as OlmNamespace from "@matrix-org/olm";
type Olm = typeof OlmNamespace;
type SignatureMap = {
export type SignatureMap = {
[userId: string]: {[deviceIdAndAlgorithm: string]: string}
}
interface BaseBackupInfo {
export type BaseBackupInfo = {
version: string,
etag: string,
count: number,
}
const Curve25519Algorithm = "m.megolm_backup.v1.curve25519-aes-sha2";
interface Curve25519BackupInfo extends BaseBackupInfo {
algorithm: typeof Curve25519Algorithm,
auth_data: Curve25519AuthData,
}
interface OtherBackupInfo extends BaseBackupInfo {
type OtherBackupInfo = BaseBackupInfo & {
algorithm: "other"
};
type BackupInfo = Curve25519BackupInfo | OtherBackupInfo;
interface Curve25519AuthData {
public_key: string,
signatures: SignatureMap
}
type AuthData = Curve25519AuthData;
type BackupInfo = Curve25519.BackupInfo | OtherBackupInfo;
type AuthData = Curve25519.AuthData;
type SessionInfo = {
first_message_index: number,
forwarded_count: number,
is_verified: boolean,
session_data: Curve29915SessionData | any
}
type Curve29915SessionData = {
ciphertext: string,
mac: string,
ephemeral: string,
session_data: Curve25519.SessionData | any
}
type MegOlmSessionKeyInfo = {
@ -83,12 +63,20 @@ type MegOlmSessionKeyInfo = {
session_key: string
}
type SessionKeyInfo = MegOlmSessionKeyInfo | {algorithm: string};
export type SessionKeyInfo = MegOlmSessionKeyInfo | {algorithm: string};
type KeyBackupPayload = {
rooms: {
[roomId: string]: {
sessions: {[sessionId: string]: SessionInfo}
}
}
}
export class KeyBackup {
constructor(
private readonly backupInfo: BackupInfo,
private readonly algorithm: Curve25519,
private readonly crypto: Curve25519.BackupEncryption,
private readonly hsApi: HomeServerApi,
private readonly keyLoader: KeyLoader,
private readonly storage: Storage,
@ -100,7 +88,7 @@ export class KeyBackup {
if (!sessionResponse.session_data) {
return;
}
const sessionKeyInfo = this.algorithm.decryptRoomKey(sessionResponse.session_data);
const sessionKeyInfo = this.crypto.decryptRoomKey(sessionResponse.session_data as Curve25519.SessionData);
if (sessionKeyInfo?.algorithm === MEGOLM_ALGORITHM) {
return keyFromBackup(roomId, sessionId, sessionKeyInfo);
} else if (sessionKeyInfo?.algorithm) {
@ -131,13 +119,7 @@ export class KeyBackup {
return;
}
const roomKeys = await Promise.all(keysNeedingBackup.map(k => keyFromStorage(k.roomId, k.senderKey, k.sessionId, txn)));
const payload: {
rooms: {
[roomId: string]: {
sessions: {[sessionId: string]: SessionInfo}
}
}
} = { rooms: {} };
const payload: KeyBackupPayload = { rooms: {} };
const payloadRooms = payload.rooms;
for (const key of roomKeys) {
if (key) {
@ -174,7 +156,7 @@ export class KeyBackup {
first_message_index: firstMessageIndex,
forwarded_count: 0,
is_verified: false,
session_data: this.algorithm.encryptRoomKey(roomKey, sessionKey)
session_data: this.crypto.encryptRoomKey(roomKey, sessionKey)
};
});
}
@ -184,7 +166,7 @@ export class KeyBackup {
}
dispose() {
this.algorithm.dispose();
this.crypto.dispose();
}
static async fromSecretStorage(platform: Platform, olm: Olm, secretStorage: SecretStorage, hsApi: HomeServerApi, keyLoader: KeyLoader, storage: Storage, txn: Transaction): Promise<KeyBackup | undefined> {
@ -192,61 +174,12 @@ export class KeyBackup {
if (base64PrivateKey) {
const privateKey = new Uint8Array(platform.encoding.base64.decode(base64PrivateKey));
const backupInfo = await hsApi.roomKeysVersion().response() as BackupInfo;
if (backupInfo.algorithm === Curve25519Algorithm) {
const algorithm = Curve25519.fromAuthData(backupInfo.auth_data, privateKey, olm);
return new KeyBackup(backupInfo, algorithm, hsApi, keyLoader, storage, platform);
if (backupInfo.algorithm === Curve25519.Algorithm) {
const crypto = Curve25519.BackupEncryption.fromAuthData(backupInfo.auth_data, privateKey, olm);
return new KeyBackup(backupInfo, crypto, hsApi, keyLoader, storage, platform);
} else {
throw new Error(`Unknown backup algorithm: ${backupInfo.algorithm}`);
}
}
}
}
class Curve25519 {
constructor(
private readonly encryption: Olm.PkEncryption,
private readonly decryption: Olm.PkDecryption
) {}
static fromAuthData(authData: Curve25519AuthData, privateKey: Uint8Array, olm: Olm): Curve25519 {
const expectedPubKey = authData.public_key;
const decryption = new olm.PkDecryption();
const encryption = new olm.PkEncryption();
try {
const pubKey = decryption.init_with_private_key(privateKey);
if (pubKey !== expectedPubKey) {
throw new Error(`Bad backup key, public key does not match. Calculated ${pubKey} but expected ${expectedPubKey}`);
}
encryption.set_recipient_key(pubKey);
} catch(err) {
decryption.free();
throw err;
}
return new Curve25519(encryption, decryption);
}
decryptRoomKey(sessionData: Curve29915SessionData): SessionKeyInfo {
const sessionInfo = this.decryption.decrypt(
sessionData.ephemeral,
sessionData.mac,
sessionData.ciphertext,
);
return JSON.parse(sessionInfo) as SessionKeyInfo;
}
encryptRoomKey(key: RoomKey, sessionKey: string): Curve29915SessionData {
const sessionInfo: SessionKeyInfo = {
algorithm: MEGOLM_ALGORITHM,
sender_key: key.senderKey,
sender_claimed_keys: {ed25519: key.claimedEd25519Key},
forwarding_curve25519_key_chain: [],
session_key: sessionKey
};
return this.encryption.encrypt(JSON.stringify(sessionInfo)) as Curve29915SessionData;
}
dispose() {
this.decryption.free();
this.encryption.free();
}
}