67 lines
2.3 KiB
Swift
67 lines
2.3 KiB
Swift
//
|
|
// Copyright 2024 Signal Messenger, LLC
|
|
// SPDX-License-Identifier: AGPL-3.0-only
|
|
//
|
|
|
|
import Foundation
|
|
import LibSignalClient
|
|
|
|
public struct MessageBackupKeyMaterialImpl: MessageBackupKeyMaterial {
|
|
|
|
private enum Constants {
|
|
static let MessageBackupIdInfoString = "20231003_Signal_Backups_GenerateBackupId"
|
|
static let MessageBackupIdLength = 16
|
|
|
|
static let MessageBackupEncryptionInfoString = "20231003_Signal_Backups_EncryptMessageBackup"
|
|
static let MessageBackupEncryptionDataLength = 80
|
|
}
|
|
|
|
private let svr: SecureValueRecovery
|
|
private let tsAccountManager: TSAccountManager
|
|
|
|
public init(svr: SecureValueRecovery, tsAccountManager: TSAccountManager) {
|
|
self.svr = svr
|
|
self.tsAccountManager = tsAccountManager
|
|
}
|
|
|
|
public func backupID(tx: DBReadTransaction) throws -> Data {
|
|
guard let backupKey = svr.data(for: .backupKey, transaction: tx) else {
|
|
throw MessageBackupKeyMaterialError.missingMasterKey
|
|
}
|
|
guard let localAci = tsAccountManager.localIdentifiers(tx: tx)?.aci else {
|
|
throw MessageBackupKeyMaterialError.notRegistered
|
|
}
|
|
guard let infoData = Constants.MessageBackupIdInfoString.data(using: .utf8) else {
|
|
owsFailDebug("Failed to encode data")
|
|
throw MessageBackupKeyMaterialError.invalidKeyInfo
|
|
}
|
|
let keyBytes = try hkdf(
|
|
outputLength: Constants.MessageBackupIdLength,
|
|
inputKeyMaterial: backupKey.rawData,
|
|
salt: localAci.serviceIdBinary,
|
|
info: infoData
|
|
)
|
|
return Data(keyBytes)
|
|
}
|
|
|
|
public func encryptionData(tx: DBReadTransaction) throws -> Data {
|
|
guard let backupKey = svr.data(for: .backupKey, transaction: tx) else {
|
|
throw MessageBackupKeyMaterialError.missingMasterKey
|
|
}
|
|
let backupId = try backupID(tx: tx)
|
|
guard let infoData = Constants.MessageBackupEncryptionInfoString.data(using: .utf8) else {
|
|
owsFailDebug("Failed to encode data")
|
|
throw MessageBackupKeyMaterialError.invalidKeyInfo
|
|
}
|
|
|
|
let keyBytes = try hkdf(
|
|
outputLength: Constants.MessageBackupEncryptionDataLength,
|
|
inputKeyMaterial: backupKey.rawData,
|
|
salt: backupId,
|
|
info: infoData
|
|
)
|
|
|
|
return Data(keyBytes)
|
|
}
|
|
}
|