Sesame-iOS/Sesame/API Extensions/SignedMessage+Crypto.swift
2023-12-12 17:33:42 +01:00

39 lines
1.1 KiB
Swift

import Foundation
import CryptoKit
extension SignedMessage {
/// The message encoded to data
var encoded: Data {
mac + message.encoded
}
var bytes: [UInt8] {
Array(encoded)
}
/**
Create a message from received bytes.
- Parameter data: The sequence of bytes
- Note: The sequence must contain at least `Message.length` bytes, or the function will crash.
*/
init(decodeFrom data: Data) throws {
guard data.count == SignedMessage.size else {
print("Invalid signed message size \(data.count)")
throw MessageResult.invalidMessageSizeFromDevice
}
let count = SHA256.byteCount
self.mac = data.prefix(count)
self.message = try Message(decodeFrom: data.dropFirst(count))
}
/**
Check if the message contains a valid authentication code
- Parameter key: The key used to sign the message.
- Returns: `true`, if the message is valid.
*/
func isValid(using key: SymmetricKey) -> Bool {
HMAC<SHA256>.isValidAuthenticationCode(mac, authenticating: message.encoded, using: key)
}
}