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Proper serialization and cleanup

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This commit is contained in:
Christoph Hagen
2022-04-28 23:19:44 +02:00
parent 360833ae5f
commit 921b9237f7
6 changed files with 110 additions and 88 deletions
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38
Sesame/API/Message+Extensions.swift
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@ -1,38 +0,0 @@
import Foundation
#if canImport(CryptoKit)
import CryptoKit
#else
import Crypto
#endif
extension Message {
static var length: Int {
SHA256.byteCount + Content.length
}
init<T: Sequence>(decodeFrom data: T) where T.Element == UInt8 {
let count = SHA256.byteCount
self.mac = Data(data.prefix(count))
self.content = .init(decodeFrom: Array(data.dropFirst(count)))
}
func isValid(using key: SymmetricKey) -> Bool {
HMAC<SHA256>.isValidAuthenticationCode(mac, authenticating: content.encoded, using: key)
}
}
extension Message.Content {
func authenticate(using key: SymmetricKey) -> Message {
let mac = HMAC<SHA256>.authenticationCode(for: encoded, using: key)
return .init(mac: Data(mac.map { $0 }), content: self)
}
func authenticateAndSerialize(using key: SymmetricKey) -> Data {
let encoded = self.encoded
let mac = HMAC<SHA256>.authenticationCode(for: encoded, using: key)
return Data(mac.map { $0 }) + encoded
}
}

117
Sesame/API/Message.swift
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@ -1,11 +1,36 @@
import Foundation
import NIOCore
#if canImport(CryptoKit)
import CryptoKit
#else
import Crypto
#endif
/**
An authenticated message to or from the device.
*/
struct Message: Equatable, Hashable {
/// The message authentication code for the message (32 bytes)
let mac: Data
/// The message content
let content: Content
/**
Create an authenticated message
- Parameter mac: The message authentication code
- Parameter content: The message content
*/
init(mac: Data, content: Content) {
self.mac = mac
self.content = content
}
}
extension Message {
/**
The message content without authentication.
*/
@ -30,13 +55,13 @@ struct Message: Equatable, Hashable {
/**
Decode message content from data.
The data consists of two `UInt32` encoded in big endian format (MSB at index 0)
The data consists of two `UInt32` encoded in little endian format
- Warning: The sequence must contain at least 8 bytes, or the function will crash.
- Parameter data: The sequence containing the bytes.
*/
init<T: Sequence>(decodeFrom data: T) where T.Element == UInt8 {
self.time = UInt32(data: data.prefix(MemoryLayout<UInt32>.size))
self.id = UInt32(data: data.dropFirst(MemoryLayout<UInt32>.size))
self.time = UInt32(data: Data(data.prefix(MemoryLayout<UInt32>.size)))
self.id = UInt32(data: Data(data.dropFirst(MemoryLayout<UInt32>.size)))
}
/// The byte length of an encoded message content
@ -48,27 +73,15 @@ struct Message: Equatable, Hashable {
var encoded: Data {
time.encoded + id.encoded
}
/// The message content encoded to bytes
var bytes: [UInt8] {
time.bytes + id.bytes
}
}
/// The message authentication code for the message (32 bytes)
let mac: Data
}
/// The message content
let content: Content
extension Message {
/**
Create an authenticated message
- Parameter mac: The message authentication code
- Parameter content: The message content
*/
init(mac: Data, content: Content) {
self.mac = mac
self.content = content
/// The length of a message in bytes
static var length: Int {
SHA256.byteCount + Content.length
}
/**
@ -88,35 +101,47 @@ struct Message: Equatable, Hashable {
mac + content.encoded
}
/// The message encoded to bytes
var bytes: [UInt8] {
Array(mac) + content.bytes
/**
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<T: Sequence>(decodeFrom data: T) where T.Element == UInt8 {
let count = SHA256.byteCount
self.mac = Data(data.prefix(count))
self.content = .init(decodeFrom: Array(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: content.encoded, using: key)
}
}
extension UInt32 {
extension Message.Content {
/**
Create a value from a big-endian data representation (MSB first)
- Note: The data must contain exactly four bytes.
*/
init<T: Sequence>(data: T) where T.Element == UInt8 {
self = data
.reversed()
.enumerated()
.map { UInt32($0.element) << ($0.offset * 8) }
.reduce(0, +)
}
/**
Calculate an authentication code for the message content.
- Parameter key: The key to use to sign the content.
- Returns: The new message signed with the key.
*/
func authenticate(using key: SymmetricKey) -> Message {
let mac = HMAC<SHA256>.authenticationCode(for: encoded, using: key)
return .init(mac: Data(mac.map { $0 }), content: self)
}
/// The value encoded to a big-endian representation
var encoded: Data {
.init(bytes)
}
/// The value encoded to a big-endian byte array
var bytes: [UInt8] {
(0..<4).reversed().map {
UInt8((self >> ($0*8)) & 0xFF)
}
}
/**
Calculate an authentication code for the message content and convert everything to data.
- Parameter key: The key to use to sign the content.
- Returns: The new message signed with the key, serialized to bytes.
*/
func authenticateAndSerialize(using key: SymmetricKey) -> Data {
let encoded = self.encoded
let mac = HMAC<SHA256>.authenticationCode(for: encoded, using: key)
return Data(mac.map { $0 }) + encoded
}
}

18
Sesame/API/UInt32+Extensions.swift Normal file
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@ -0,0 +1,18 @@
import Foundation
extension UInt32 {
/**
Create a value from a little-endian data representation (MSB first)
- Note: The data must contain exactly four bytes.
*/
init(data: Data) {
let value = data.convert(into: UInt32.zero)
self = CFSwapInt32LittleToHost(value)
}
/// The value encoded to a little-endian representation
var encoded: Data {
Data(from: CFSwapInt32HostToLittle(self))
}
}