有關在.net framework 4.7中執行ECDiffieHellmanCng的祕密協議的問題？

我有以下代碼：有關在.net framework 4.7中執行ECDiffieHellmanCng的祕密協議的問題？

 var curve = ECCurve.NamedCurves.nistP256; 
     var ecdhSender = ECDiffieHellman.Create(curve); 
     var ecdhReceiver = ECDiffieHellman.Create(curve);

我的理解是，我應該能夠計算祕密協議，無論是從使用ecdhSender對象使用ecdhReceiver.PublicKey或使用與ecdhSender.PublicKey ecdhReceiver對象和兩個祕密協議值應相同。如果這是一個錯誤的假設，請讓我知道。

由於ECDiffieHellman.Create返回ECDiffieHellman類型，我寫了下面的代碼來獲取祕密協議：

 string receiverHexString = null; 
     using (SafeNCryptSecretHandle secretAgreement = (ecdhReceiver as ECDiffieHellmanCng).DeriveSecretAgreementHandle(ecdhSender.PublicKey)) 
     { 
      byte[] secretAgreementBytes = new byte[32]; 
      IntPtr pointer = secretAgreement.DangerousGetHandle(); 
      Marshal.Copy(pointer, secretAgreementBytes, 0, secretAgreementBytes.Length); 
      receiverHexString = BitConverter.ToString(secretAgreementBytes).Replace("-", string.Empty).ToLower(); 
      Console.WriteLine($"receiver secretAgreement: 0x{receiverHexString}"); 
     } 

     string senderHexString = null; 
     using (SafeNCryptSecretHandle secretAgreement = (ecdhSender as ECDiffieHellmanCng).DeriveSecretAgreementHandle(ecdhReceiver.PublicKey)) 
     { 
      byte[] secretAgreementBytes = new byte[32]; 
      IntPtr pointer = secretAgreement.DangerousGetHandle(); 
      Marshal.Copy(pointer, secretAgreementBytes, 0, secretAgreementBytes.Length); 
      senderHexString = BitConverter.ToString(secretAgreementBytes).Replace("-", string.Empty).ToLower(); 
      Console.WriteLine($"sender secretAgreement: 0x{senderHexString}"); 
     } 

     Assert.AreEqual(receiverHexString, senderHexString);

我斷言失敗。顯然我做錯了一些事情（如果祕密協議應該是相同的）。

難道我是如何提取字節的句柄嗎？或者是其他東西？

來源

2017-10-13 Raghu

你想完成什麼？ NCRYPT_SECRET_HANDLE結構是不透明的，你不應該讀它的內存。 – bartonjs

嘗試使用詳細步驟驗證來自合作伙伴的結果。如果在我的問題的第一部分中，我的假設是正確的還是錯誤的，請您評論一下嗎？ – Raghu

從last time I checked開始，沒有文檔記載的方式從CNG獲取原始祕密協議值，這就是.NET不公開它的原因。

在.NET的預期使用ECDH的是

ECCurve curve = ECCurve.NamedCurves.nistP256; 

// Usually you'll only have one private key (yours), so this isn't representative of 
// real code. An `ECDiffieHellman` object doesn't necessarily have a private key, 
// but an `ECDiffieHellmanPublicKey` object definitely doesn't. 
using (ECDiffieHellman bobPrivate = ECDiffieHellman.Create(curve)) 
using (ECDiffieHellman alicePrivate = ECDiffieHellman.Create(curve)) 
using (ECDiffieHellmanPublicKey bobPublic = bobPrivate.PublicKey) 
using (ECDiffieHellmanPublicKey alicePublic = alicePrivate.PublicKey) 
{ 
    byte[] ba = bobPrivate.DeriveKeyFromHash(alicePublic, HashAlgorithmName.SHA256); 
    byte[] ab = alicePrivate.DeriveKeyFromHash(bobPublic, HashAlgorithmName.SHA256); 

    // ba and ab have the same contents. 
}

還有

DeriveKeyFromHash(ECDiffieHellmanPublicKey otherPartyPublicKey, HashAlgorithmName hashAlgorithm, byte[] secretPrepend, byte[] secretAppend)
DeriveKeyFromHmac(ECDiffieHellmanPublicKey otherPartyPublicKey, HashAlgorithmName hashAlgorithm, byte[] hmacKey)
DeriveKeyFromHmac(ECDiffieHellmanPublicKey otherPartyPublicKey, HashAlgorithmName hashAlgorithm, byte[] hmacKey, byte[] secretPrepend, byte[] secretAppend)
DeriveKeyTls(ECDiffieHellmanPublicKey otherPartyPublicKey, byte[] prfLabel, byte[] prfSeed)

如果bobPrivate和alicePublic（或者相反，alicePrivate和bobPublic）不變，那麼提供相同的輸入將產生相同的輸出。

注意：你應該避免專門討論ECDiffieHellmanCng，如果可以的話。當ECDH最終將其轉換爲.NET標準時，ECDHCng類不會。從.NET 4.6.2開始，一切都可以在基類上完成（打開持久鍵除外）;而.NET Core往往不會從其工廠方法中返回公共類型。

來源

2017-10-16 15:07:34 bartonjs

有關在.net framework 4.7中執行ECDiffieHellmanCng的祕密協議的問題？

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