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cleanup of olm encryption

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This commit is contained in:
Bruno Windels 2020-09-03 09:53:16 +02:00
parent e3daef5ca9
commit 1492b6b6f8
1 changed files with 102 additions and 64 deletions
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166
src/matrix/e2ee/olm/Encryption.js
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@ -42,6 +42,39 @@ export class Encryption {
}
async encrypt(type, content, devices, hsApi) {
const {
devicesWithoutSession,
existingEncryptionTargets
} = await this._findExistingSessions(devices);
const timestamp = this._now();
let encryptionTargets = [];
try {
if (devicesWithoutSession.length) {
const newEncryptionTargets = await this._createNewSessions(
devicesWithoutSession, hsApi, timestamp);
encryptionTargets = encryptionTargets.concat(newEncryptionTargets);
}
// TODO: if we read and write in two different txns,
// is there a chance we overwrite a session modified by the decryption during sync?
// I think so. We'll have to have a lock while sending ...
await this._loadSessions(existingEncryptionTargets);
encryptionTargets = encryptionTargets.concat(existingEncryptionTargets);
const messages = encryptionTargets.map(target => {
const content = this._encryptForDevice(type, content, target);
return new EncryptedMessage(content, target.device);
});
await this._storeSessions(encryptionTargets, timestamp);
return messages;
} finally {
for (const target of encryptionTargets) {
target.dispose();
}
}
}
async _findExistingSessions(devices) {
const txn = this._storage.readTxn([this._storage.storeNames.olmSessions]);
const sessionIdsForDevice = await Promise.all(devices.map(async device => {
return await txn.olmSessions.getSessionIds(device.curve25519Key);
@ -51,49 +84,28 @@ export class Encryption {
return !(sessionIds?.length);
});
const timestamp = this._now();
let encryptionTuples = [];
if (devicesWithoutSession.length) {
const newEncryptionTuples = await this._claimOneTimeKeys(hsApi, devicesWithoutSession);
try {
for (const tuple of newEncryptionTuples) {
const {device, oneTimeKey} = tuple;
tuple.session = this._account.createOutboundOlmSession(device.curve25519Key, oneTimeKey);
}
this._storeSessions(newEncryptionTuples, timestamp);
} catch (err) {
for (const tuple of newEncryptionTuples) {
tuple.dispose();
}
}
encryptionTuples = encryptionTuples.concat(newEncryptionTuples);
}
const existingEncryptionTuples = devices.map((device, i) => {
const existingEncryptionTargets = devices.map((device, i) => {
const sessionIds = sessionIdsForDevice[i];
if (sessionIds?.length > 0) {
const sessionId = findFirstSessionId(sessionIds);
return EncryptionTuple.fromSessionId(device, sessionId);
return EncryptionTarget.fromSessionId(device, sessionId);
}
}).filter(tuple => !!tuple);
// TODO: if we read and write in two different txns,
// is there a chance we overwrite a session modified by the decryption during sync?
// I think so. We'll have to have a lock while sending ...
await this._loadSessions(existingEncryptionTuples);
encryptionTuples = encryptionTuples.concat(existingEncryptionTuples);
const ciphertext = this._buildCipherText(type, content, encryptionTuples);
await this._storeSessions(encryptionTuples, timestamp);
return {
type: "m.room.encrypted",
content: {
algorithm: OLM_ALGORITHM,
sender_key: this._account.identityKeys.curve25519,
ciphertext
}).filter(target => !!target);
return {devicesWithoutSession, existingEncryptionTargets};
}
_encryptForDevice(type, content, target) {
const {session, device} = target;
const message = session.encrypt(this._buildPlainTextMessageForDevice(type, content, device));
const encryptedContent = {
algorithm: OLM_ALGORITHM,
sender_key: this._account.identityKeys.curve25519,
ciphertext: {
[device.curve25519Key]: message
}
};
return encryptedContent;
}
_buildPlainTextMessageForDevice(type, content, device) {
@ -111,15 +123,20 @@ export class Encryption {
}
}
_buildCipherText(type, content, encryptionTuples) {
const ciphertext = {};
for (const {device, session} of encryptionTuples) {
if (session) {
const message = session.encrypt(this._buildPlainTextMessageForDevice(type, content, device));
ciphertext[device.curve25519Key] = message;
async _createNewSessions(devicesWithoutSession, hsApi, timestamp) {
const newEncryptionTargets = await this._claimOneTimeKeys(hsApi, devicesWithoutSession);
try {
for (const target of newEncryptionTargets) {
const {device, oneTimeKey} = target;
target.session = this._account.createOutboundOlmSession(device.curve25519Key, oneTimeKey);
}
this._storeSessions(newEncryptionTargets, timestamp);
} catch (err) {
for (const target of newEncryptionTargets) {
target.dispose();
}
}
return ciphertext;
return newEncryptionTargets;
}
async _claimOneTimeKeys(hsApi, deviceIdentities) {
@ -142,11 +159,11 @@ export class Encryption {
}).response();
// TODO: log claimResponse.failures
const userKeyMap = claimResponse?.["one_time_keys"];
return this._verifyAndCreateOTKTuples(userKeyMap, devicesByUser);
return this._verifyAndCreateOTKTargets(userKeyMap, devicesByUser);
}
_verifyAndCreateOTKTuples(userKeyMap, devicesByUser) {
const verifiedEncryptionTuples = [];
_verifyAndCreateOTKTargets(userKeyMap, devicesByUser) {
const verifiedEncryptionTargets = [];
for (const [userId, userSection] of Object.entries(userKeyMap)) {
for (const [deviceId, deviceSection] of Object.entries(userSection)) {
const [firstPropName, keySection] = Object.entries(deviceSection)[0];
@ -157,34 +174,48 @@ export class Encryption {
const isValidSignature = verifyEd25519Signature(
this._olmUtil, userId, deviceId, device.ed25519Key, keySection);
if (isValidSignature) {
verifiedEncryptionTuples.push(EncryptionTuple.fromOTK(device, keySection.key));
const target = EncryptionTarget.fromOTK(device, keySection.key);
verifiedEncryptionTargets.push(target);
}
}
}
}
}
return verifiedEncryptionTuples;
return verifiedEncryptionTargets;
}
async _loadSessions(encryptionTuples) {
async _loadSessions(encryptionTargets) {
const txn = this._storage.readTxn([this._storage.storeNames.olmSessions]);
await Promise.all(encryptionTuples.map(async encryptionTuple => {
const sessionEntry = await txn.olmSessions.get(
encryptionTuple.device.curve25519Key, encryptionTuple.sessionId);
if (sessionEntry) {
const olmSession = new this._olm.Session();
encryptionTuple.session =
// given we run loading in parallel, there might still be some
// storage requests that will finish later once one has failed.
// those should not allocate a session anymore.
let failed = false;
try {
await Promise.all(encryptionTargets.map(async encryptionTarget => {
const sessionEntry = await txn.olmSessions.get(
encryptionTarget.device.curve25519Key, encryptionTarget.sessionId);
if (sessionEntry && !failed) {
const olmSession = new this._olm.Session();
olmSession.unpickle(this._pickleKey, sessionEntry.session);
encryptionTarget.session = olmSession;
}
}));
} catch (err) {
failed = true;
// clean up the sessions that did load
for (const target of encryptionTargets) {
target.dispose();
}
}));
throw err;
}
}
async _storeSessions(encryptionTuples, timestamp) {
async _storeSessions(encryptionTargets, timestamp) {
const txn = this._storage.readWriteTxn([this._storage.storeNames.olmSessions]);
try {
for (const tuple of encryptionTuples) {
for (const target of encryptionTargets) {
const sessionEntry = createSessionEntry(
tuple.session, tuple.device.curve25519Key, timestamp, this._pickleKey);
target.session, target.device.curve25519Key, timestamp, this._pickleKey);
txn.olmSessions.set(sessionEntry);
}
} catch (err) {
@ -199,7 +230,7 @@ export class Encryption {
// it is constructed with either a oneTimeKey
// (and later converted to a session) in case of a new session
// or an existing session
class EncryptionTuple {
class EncryptionTarget {
constructor(device, oneTimeKey, sessionId) {
this.device = device;
this.oneTimeKey = oneTimeKey;
@ -209,11 +240,11 @@ class EncryptionTuple {
}
static fromOTK(device, oneTimeKey) {
return new EncryptionTuple(device, oneTimeKey, null);
return new EncryptionTarget(device, oneTimeKey, null);
}
static fromSessionId(device, sessionId) {
return new EncryptionTuple(device, null, sessionId);
return new EncryptionTarget(device, null, sessionId);
}
dispose() {
@ -222,3 +253,10 @@ class EncryptionTuple {
}
}
}
class EncryptedMessage {
constructor(content, device) {
this.content = content;
this.device = device;
}
}