IceCubesApp/IceCubesNotifications/NotificationServiceSupport.swift
2023-01-08 14:16:43 +01:00

86 lines
2.8 KiB
Swift
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This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

import Foundation
import CryptoKit
extension NotificationService {
static func decrypt(payload: Data, salt: Data, auth: Data, privateKey: P256.KeyAgreement.PrivateKey, publicKey: P256.KeyAgreement.PublicKey) -> Data? {
guard let sharedSecret = try? privateKey.sharedSecretFromKeyAgreement(with: publicKey) else {
return nil
}
let keyMaterial = sharedSecret.hkdfDerivedSymmetricKey(using: SHA256.self, salt: auth, sharedInfo: Data("Content-Encoding: auth\0".utf8), outputByteCount: 32)
let keyInfo = info(type: "aesgcm", clientPublicKey: privateKey.publicKey.x963Representation, serverPublicKey: publicKey.x963Representation)
let key = HKDF<SHA256>.deriveKey(inputKeyMaterial: keyMaterial, salt: salt, info: keyInfo, outputByteCount: 16)
let nonceInfo = info(type: "nonce", clientPublicKey: privateKey.publicKey.x963Representation, serverPublicKey: publicKey.x963Representation)
let nonce = HKDF<SHA256>.deriveKey(inputKeyMaterial: keyMaterial, salt: salt, info: nonceInfo, outputByteCount: 12)
let nonceData = nonce.withUnsafeBytes(Array.init)
guard let sealedBox = try? AES.GCM.SealedBox(combined: nonceData + payload) else {
return nil
}
var _plaintext: Data?
do {
_plaintext = try AES.GCM.open(sealedBox, using: key)
} catch {
print(error)
}
guard let plaintext = _plaintext else {
return nil
}
let paddingLength = Int(plaintext[0]) * 256 + Int(plaintext[1])
guard plaintext.count >= 2 + paddingLength else {
print("1")
fatalError()
}
let unpadded = plaintext.suffix(from: paddingLength + 2)
return Data(unpadded)
}
static private func info(type: String, clientPublicKey: Data, serverPublicKey: Data) -> Data {
var info = Data()
info.append("Content-Encoding: ".data(using: .utf8)!)
info.append(type.data(using: .utf8)!)
info.append(0)
info.append("P-256".data(using: .utf8)!)
info.append(0)
info.append(0)
info.append(65)
info.append(clientPublicKey)
info.append(0)
info.append(65)
info.append(serverPublicKey)
return info
}
}
extension String {
func escape() -> String {
return self
.replacingOccurrences(of: "&amp;", with: "&")
.replacingOccurrences(of: "&lt;", with: "<")
.replacingOccurrences(of: "&gt;", with: ">")
.replacingOccurrences(of: "&quot;", with: "\"")
.replacingOccurrences(of: "&apos;", with: "'")
.replacingOccurrences(of: "&#39;", with: "")
}
func URLSafeBase64ToBase64() -> String {
var base64 = replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/")
let countMod4 = count % 4
if countMod4 != 0 {
base64.append(String(repeating: "=", count: 4 - countMod4))
}
return base64
}
}