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calculateDefaultKey() -> unlockAndLoad() + more refactoring
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1. The rename is because it does so much more than just default key
   calculation.
2. Speaking of the default key, it's now only retrieved once, not 5
   times.
3. The default key "event" type definition can be removed now that
   usage of it becomes one-time access of a single key.
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@KitsuneRal
Kitsune Ral authored and KitsuneRal committed Mar 13, 2024
1 parent c81af2e commit 8dddb64
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Showing 2 changed files with 25 additions and 31 deletions.
51 changes: 22 additions & 29 deletions Quotient/e2ee/sssshandler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -16,31 +16,25 @@

using namespace Quotient;

DEFINE_SIMPLE_EVENT(SecretStorageDefaultKeyEvent, Event, "m.secret_storage.default_key", QString, key, "key");

namespace {
constexpr inline auto MegolmBackupKey = "m.megolm_backup.v1"_ls;
constexpr inline auto CrossSigningMasterKey = "m.cross_signing.master"_ls;
constexpr inline auto CrossSigningSelfSigningKey = "m.cross_signing.self_signing"_ls;
constexpr inline auto CrossSigningUserSigningKey = "m.cross_signing.user_signing"_ls;
}

QByteArray SSSSHandler::decryptKey(event_type_t keyType, const QByteArray& decryptionKey)
QByteArray SSSSHandler::decryptKey(event_type_t keyType, const QString& defaultKey,
const QByteArray& decryptionKey)
{
Q_ASSERT(m_connection);
const auto defaultKeyEvent = m_connection->accountData<SecretStorageDefaultKeyEvent>();
if (!defaultKeyEvent) {
qCWarning(E2EE) << "No default secret storage key";
emit error(NoKeyError);
return {};
}
const auto& encryptedKeyObject = m_connection->accountData<Event>(keyType);
const auto& encryptedKeyObject = m_connection->accountData(keyType);
if (!encryptedKeyObject) {
qWarning() << "No account data for key" << keyType;
emit error(NoKeyError);
return {};
}
const auto& encrypted = encryptedKeyObject->contentPart<QJsonObject>("encrypted"_ls)
.value(defaultKeyEvent->key())
.toObject();
const auto& encrypted =
encryptedKeyObject->contentPart<QJsonObject>("encrypted"_ls).value(defaultKey).toObject();

auto hkdfResult = hkdfSha256(decryptionKey, QByteArray(32, u'\0'), keyType.data());
if (!hkdfResult.has_value()) {
Expand Down Expand Up @@ -76,7 +70,7 @@ QByteArray SSSSHandler::decryptKey(event_type_t keyType, const QByteArray& decry
void SSSSHandler::unlockSSSSFromPassword(const QString& password)
{
Q_ASSERT(m_connection);
calculateDefaultKey(password.toLatin1(), true);
unlockAndLoad(password.toLatin1(), true);
}

void SSSSHandler::unlockSSSSFromCrossSigning()
Expand Down Expand Up @@ -147,16 +141,15 @@ void SSSSHandler::loadMegolmBackup(const QByteArray& megolmDecryptionKey)
});
}

void SSSSHandler::calculateDefaultKey(const QByteArray& secret,
bool requirePassphrase)
void SSSSHandler::unlockAndLoad(QByteArray&& secret, bool requirePassphrase)
{
auto key = secret;
if (!m_connection->hasAccountData(SecretStorageDefaultKeyEvent::TypeId)) {
const auto& defaultKeyEvent = m_connection->accountData("m.secret_storage.default_key"_ls);
if (!defaultKeyEvent) {
qCWarning(E2EE) << "No default secret storage key";
emit error(NoKeyError);
return;
}
const auto defaultKey = m_connection->accountData<SecretStorageDefaultKeyEvent>()->key();
const auto defaultKey = defaultKeyEvent->contentPart<QString>("key"_ls);
if (!m_connection->hasAccountData("m.secret_storage.key."_ls + defaultKey)) {
qCWarning(E2EE) << "No account data for key" << ("m.secret_storage.key."_ls + defaultKey);
emit error(NoKeyError);
Expand All @@ -177,16 +170,16 @@ void SSSSHandler::calculateDefaultKey(const QByteArray& secret,
return;
}

auto result = pbkdf2HmacSha512(secret, passphraseJson["salt"_ls].toString().toLatin1(), passphraseJson["iterations"_ls].toInt(), 32);
auto&& result = pbkdf2HmacSha512(secret, passphraseJson["salt"_ls].toString().toLatin1(), passphraseJson["iterations"_ls].toInt(), 32);
if (!result.has_value()) {
qCWarning(E2EE) << "Failed to calculate pbkdf";
emit error(DecryptionError);
return;
}
key = result.value();
secret = std::move(result.value());
}

const auto &testKeys = hkdfSha256(key, QByteArray(32, u'\0'), {});
const auto& testKeys = hkdfSha256(secret, QByteArray(32, u'\0'), {});
if (!testKeys.has_value()) {
qCWarning(E2EE) << "Failed to calculate hkdf";
emit error(DecryptionError);
Expand Down Expand Up @@ -215,12 +208,12 @@ void SSSSHandler::calculateDefaultKey(const QByteArray& secret,

emit keyBackupUnlocked();

auto megolmDecryptionKey = decryptKey(MegolmBackupKey, key);
auto megolmDecryptionKey = decryptKey(MegolmBackupKey, defaultKey, secret);

// These keys are only decrypted since this will automatically store them locally
decryptKey(CrossSigningSelfSigningKey, key);
decryptKey(CrossSigningUserSigningKey, key);
decryptKey(CrossSigningMasterKey, key);
decryptKey(CrossSigningSelfSigningKey, defaultKey, secret);
decryptKey(CrossSigningUserSigningKey, defaultKey, secret);
decryptKey(CrossSigningMasterKey, defaultKey, secret);
if (megolmDecryptionKey.isEmpty()) {
qCWarning(E2EE) << "No megolm decryption key";
emit error(NoKeyError);
Expand All @@ -233,7 +226,7 @@ void SSSSHandler::unlockSSSSFromSecurityKey(const QString& key)
{
auto securityKey = key;
securityKey.remove(u' ');
auto decoded = base58Decode(securityKey.toLatin1());
auto&& decoded = base58Decode(securityKey.toLatin1());
unsigned char parity = 0;
for (const auto b : decoded) {
parity ^= b;
Expand All @@ -248,13 +241,13 @@ void SSSSHandler::unlockSSSSFromSecurityKey(const QString& key)
emit error(WrongKeyError);
return;
}
if (decoded.length() != 32 + 3) {
if (decoded.size() != 32 + 3) {
qCWarning(E2EE) << "Incorrect length";
emit error(WrongKeyError);
return;
}
decoded = decoded.mid(2);
decoded.chop(1);

calculateDefaultKey(decoded, false);
unlockAndLoad(std::move(decoded), false);
}
5 changes: 3 additions & 2 deletions Quotient/e2ee/sssshandler.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,9 +48,10 @@ class QUOTIENT_API SSSSHandler : public QObject
QPointer<Connection> m_connection;

//! \brief Decrypt the key with this name from the account data
QByteArray decryptKey(event_type_t keyType, const QByteArray& decryptionKey);
QByteArray decryptKey(event_type_t keyType, const QString& defaultKey,
const QByteArray& decryptionKey);

void loadMegolmBackup(const QByteArray& megolmDecryptionKey);
void calculateDefaultKey(const QByteArray& secret, bool requirePassphrase);
void unlockAndLoad(QByteArray&& secret, bool requirePassphrase);
};
} // namespace Quotient

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