ios - iOS - 如何在 iOS 12 中执行 sharedSecretFromKeyAgreement

Question

最近，Apple 在 iOS 13 中引入了 CryptoKit，它有一个方法 sharedSecretFromKeyAgreement，它根据公钥和私钥之间的密钥协议生成共享密钥。这如何在 iOS 12 及更低版本中实现？

iOS 13

import CryptoKit

let alicePrivateKey = P256.KeyAgreement.PrivateKey()
let alicePublicKey = alicePrivateKey.publicKey

let eileenPrivateKey = P256.KeyAgreement.PrivateKey()
let eileenPublicKey = eileenPrivateKey.publicKey

let shared1 = try alicePrivateKey.sharedSecretFromKeyAgreement(with: eileenPublicKey)
let shared2 = try eileenPrivateKey.sharedSecretFromKeyAgreement(with: alicePublicKey)

if shared1 == shared2 {
    print("shared keys are equal")
}

Answer 1

我使用了来自 iOS 的 SecKeyCopyKeyExchangeResult，它工作正常，没有问题。唯一要确保的是下面使用的 ecSecPrivateKey 和 ecSecPrivateKey 应该是 Seckey 格式并且应该可以正常工作。

 guard let derivedData = SecKeyCopyKeyExchangeResult(
                ecSecPrivateKey,
                SecKeyAlgorithm.ecdhKeyExchangeStandard,
                ecSecPublicKey,
                parameters as CFDictionary,
                &error)
                else {
                return
            }

Answer 2

import CryptoKit
import Foundation

let bobsPrivateKey = P521.KeyAgreement.PrivateKey()
let bobsPublicKey = bobsPrivateKey.publicKey

let alicesPrivateKey = P521.KeyAgreement.PrivateKey()
let alicesPublicKey = alicesPrivateKey.publicKey

let shared1 = try alicesPrivateKey.sharedSecretFromKeyAgreement(with: bobsPublicKey)
let shared2 = try bobsPrivateKey.sharedSecretFromKeyAgreement(with: alicesPublicKey)

if shared1 == shared2 {
    print("shared keys are equal")
}