Refactoring
This commit is contained in:
Justin Mazzocchi
parent
98a80e5704
commit
aea6030d43
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@ -1,10 +1,7 @@
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// Copyright © 2020 Metabolist. All rights reserved.
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import CryptoKit
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import Keychain
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import Kingfisher
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import Mastodon
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import Secrets
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import ServiceLayer
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import UserNotifications
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@ -28,13 +25,13 @@ final class NotificationService: UNNotificationServiceExtension {
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guard let bestAttemptContent = bestAttemptContent else { return }
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let pushNotification: PushNotification
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let parsingService = PushNotificationParsingService(environment: environment)
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let decryptedJSON: Data
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let identityId: Identity.Id
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let pushNotification: PushNotification
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do {
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(decryptedJSON, identityId) = try Self.extractAndDecrypt(userInfo: request.content.userInfo)
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(decryptedJSON, identityId) = try parsingService.extractAndDecrypt(userInfo: request.content.userInfo)
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pushNotification = try MastodonDecoder().decode(PushNotification.self, from: decryptedJSON)
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} catch {
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contentHandler(bestAttemptContent)
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@ -72,105 +69,7 @@ final class NotificationService: UNNotificationServiceExtension {
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}
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}
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enum NotificationServiceError: Error {
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case userInfoDataAbsent
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case keychainDataAbsent
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}
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private extension NotificationService {
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static let identityIdUserInfoKey = "i"
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static let encryptedMessageUserInfoKey = "m"
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static let saltUserInfoKey = "s"
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static let serverPublicKeyUserInfoKey = "k"
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static let keyLength = 16
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static let nonceLength = 12
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static let pseudoRandomKeyLength = 32
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static let paddedByteCount = 2
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static let curve = "P-256"
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enum HKDFInfo: String {
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case auth, aesgcm, nonce
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var bytes: [UInt8] {
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Array("Content-Encoding: \(self)\0".utf8)
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}
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}
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static func extractAndDecrypt(userInfo: [AnyHashable: Any]) throws -> (Data, Identity.Id) {
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guard
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let identityIdString = userInfo[identityIdUserInfoKey] as? String,
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let identityId = Identity.Id(uuidString: identityIdString),
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let encryptedMessageBase64 = (userInfo[encryptedMessageUserInfoKey] as? String)?.URLSafeBase64ToBase64(),
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let encryptedMessage = Data(base64Encoded: encryptedMessageBase64),
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let saltBase64 = (userInfo[saltUserInfoKey] as? String)?.URLSafeBase64ToBase64(),
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let salt = Data(base64Encoded: saltBase64),
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let serverPublicKeyBase64 = (userInfo[serverPublicKeyUserInfoKey] as? String)?.URLSafeBase64ToBase64(),
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let serverPublicKeyData = Data(base64Encoded: serverPublicKeyBase64)
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else { throw NotificationServiceError.userInfoDataAbsent }
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let secretsService = Secrets(identityId: identityId, keychain: LiveKeychain.self)
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guard
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let auth = try secretsService.getPushAuth(),
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let pushKey = try secretsService.getPushKey()
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else { throw NotificationServiceError.keychainDataAbsent }
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return (try decrypt(encryptedMessage: encryptedMessage,
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privateKeyData: pushKey,
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serverPublicKeyData: serverPublicKeyData,
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auth: auth,
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salt: salt),
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identityId)
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}
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static func decrypt(encryptedMessage: Data,
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privateKeyData: Data,
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serverPublicKeyData: Data,
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auth: Data,
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salt: Data) throws -> Data {
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let privateKey = try P256.KeyAgreement.PrivateKey(x963Representation: privateKeyData)
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let serverPublicKey = try P256.KeyAgreement.PublicKey(x963Representation: serverPublicKeyData)
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let sharedSecret = try privateKey.sharedSecretFromKeyAgreement(with: serverPublicKey)
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var keyInfo = HKDFInfo.aesgcm.bytes
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var nonceInfo = HKDFInfo.nonce.bytes
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var context = Array(curve.utf8)
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let publicKeyData = privateKey.publicKey.x963Representation
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context.append(0)
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context.append(0)
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context.append(UInt8(publicKeyData.count))
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context += Array(publicKeyData)
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context.append(0)
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context.append(UInt8(serverPublicKeyData.count))
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context += Array(serverPublicKeyData)
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keyInfo += context
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nonceInfo += context
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let pseudoRandomKey = sharedSecret.hkdfDerivedSymmetricKey(
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using: SHA256.self,
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salt: auth,
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sharedInfo: HKDFInfo.auth.bytes,
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outputByteCount: pseudoRandomKeyLength)
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let key = HKDF<SHA256>.deriveKey(
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inputKeyMaterial: pseudoRandomKey,
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salt: salt,
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info: keyInfo,
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outputByteCount: keyLength)
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let nonce = HKDF<SHA256>.deriveKey(
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inputKeyMaterial: pseudoRandomKey,
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salt: salt,
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info: nonceInfo,
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outputByteCount: nonceLength)
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let sealedBox = try AES.GCM.SealedBox(combined: nonce.withUnsafeBytes(Array.init) + encryptedMessage)
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let decrypted = try AES.GCM.open(sealedBox, using: key)
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let unpadded = decrypted.suffix(from: paddedByteCount)
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return Data(unpadded)
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}
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static func addImage(pushNotification: PushNotification,
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bestAttemptContent: UNMutableNotificationContent,
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contentHandler: @escaping (UNNotificationContent) -> Void) {
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@ -208,16 +107,3 @@ private extension NotificationService {
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}
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}
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}
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extension String {
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func URLSafeBase64ToBase64() -> String {
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var base64 = replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/")
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let countMod4 = count % 4
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if countMod4 != 0 {
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base64.append(String(repeating: "=", count: 4 - countMod4))
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}
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return base64
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}
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}
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@ -0,0 +1,129 @@
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// Copyright © 2021 Metabolist. All rights reserved.
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import CryptoKit
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import Foundation
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import Mastodon
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import Secrets
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enum NotificationExtensionServiceError: Error {
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case userInfoDataAbsent
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case keychainDataAbsent
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}
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public struct PushNotificationParsingService {
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private let environment: AppEnvironment
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public init(environment: AppEnvironment) {
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self.environment = environment
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}
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}
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public extension PushNotificationParsingService {
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func extractAndDecrypt(userInfo: [AnyHashable: Any]) throws -> (Data, Identity.Id) {
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guard let identityIdString = userInfo[Self.identityIdUserInfoKey] as? String,
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let identityId = Identity.Id(uuidString: identityIdString),
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let encryptedMessageBase64 = (userInfo[Self.encryptedMessageUserInfoKey] as? String)?
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.URLSafeBase64ToBase64(),
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let encryptedMessage = Data(base64Encoded: encryptedMessageBase64),
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let saltBase64 = (userInfo[Self.saltUserInfoKey] as? String)?.URLSafeBase64ToBase64(),
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let salt = Data(base64Encoded: saltBase64),
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let serverPublicKeyBase64 = (userInfo[Self.serverPublicKeyUserInfoKey] as? String)?
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.URLSafeBase64ToBase64(),
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let serverPublicKeyData = Data(base64Encoded: serverPublicKeyBase64)
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else { throw NotificationExtensionServiceError.userInfoDataAbsent }
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let secrets = Secrets(identityId: identityId, keychain: environment.keychain)
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guard let auth = try secrets.getPushAuth(),
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let pushKey = try secrets.getPushKey()
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else { throw NotificationExtensionServiceError.keychainDataAbsent }
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return (try Self.decrypt(encryptedMessage: encryptedMessage,
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privateKeyData: pushKey,
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serverPublicKeyData: serverPublicKeyData,
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auth: auth,
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salt: salt),
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identityId)
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}
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}
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private extension PushNotificationParsingService {
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static let identityIdUserInfoKey = "i"
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static let encryptedMessageUserInfoKey = "m"
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static let saltUserInfoKey = "s"
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static let serverPublicKeyUserInfoKey = "k"
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static let keyLength = 16
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static let nonceLength = 12
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static let pseudoRandomKeyLength = 32
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static let paddedByteCount = 2
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static let curve = "P-256"
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enum HKDFInfo: String {
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case auth, aesgcm, nonce
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var bytes: [UInt8] {
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Array("Content-Encoding: \(self)\0".utf8)
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}
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}
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static func decrypt(encryptedMessage: Data,
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privateKeyData: Data,
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serverPublicKeyData: Data,
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auth: Data,
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salt: Data) throws -> Data {
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let privateKey = try P256.KeyAgreement.PrivateKey(x963Representation: privateKeyData)
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let serverPublicKey = try P256.KeyAgreement.PublicKey(x963Representation: serverPublicKeyData)
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let sharedSecret = try privateKey.sharedSecretFromKeyAgreement(with: serverPublicKey)
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var keyInfo = HKDFInfo.aesgcm.bytes
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var nonceInfo = HKDFInfo.nonce.bytes
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var context = Array(curve.utf8)
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let publicKeyData = privateKey.publicKey.x963Representation
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context.append(0)
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context.append(0)
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context.append(UInt8(publicKeyData.count))
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context += Array(publicKeyData)
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context.append(0)
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context.append(UInt8(serverPublicKeyData.count))
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context += Array(serverPublicKeyData)
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keyInfo += context
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nonceInfo += context
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let pseudoRandomKey = sharedSecret.hkdfDerivedSymmetricKey(
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using: SHA256.self,
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salt: auth,
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sharedInfo: HKDFInfo.auth.bytes,
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outputByteCount: pseudoRandomKeyLength)
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let key = HKDF<SHA256>.deriveKey(
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inputKeyMaterial: pseudoRandomKey,
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salt: salt,
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info: keyInfo,
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outputByteCount: keyLength)
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let nonce = HKDF<SHA256>.deriveKey(
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inputKeyMaterial: pseudoRandomKey,
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salt: salt,
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info: nonceInfo,
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outputByteCount: nonceLength)
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let sealedBox = try AES.GCM.SealedBox(combined: nonce.withUnsafeBytes(Array.init) + encryptedMessage)
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let decrypted = try AES.GCM.open(sealedBox, using: key)
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let unpadded = decrypted.suffix(from: paddedByteCount)
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return Data(unpadded)
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}
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}
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private extension String {
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func URLSafeBase64ToBase64() -> String {
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var base64 = replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/")
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let countMod4 = count % 4
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if countMod4 != 0 {
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base64.append(String(repeating: "=", count: 4 - countMod4))
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}
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return base64
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}
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}
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