static public byte[] DiffieHellmanGetSecretKey(string publicKey, out string thisPublicKey)
{
var df = new ECDiffieHellmanCng(256);
thisPublicKey = df.PublicKey.ToXmlString();
return(df.DeriveKeyMaterial(ECDiffieHellmanCngPublicKey.FromXmlString(publicKey)));
}
public static byte[] DeriveKeyMaterial(byte[] privateKey, byte[] otherPublicKey, CngAlgorithm hashAlgorithm)
{
#if Mono
throw new NotSupportedException();
#else
using (CngKey ck = CngKey.Import(privateKey, CngKeyBlobFormat.Pkcs8PrivateBlob))
using (ECDiffieHellmanCng ecdh = new ECDiffieHellmanCng(ck))
{
ecdh.HashAlgorithm = hashAlgorithm;
return(ecdh.DeriveKeyMaterial(ECDiffieHellmanCngPublicKey.FromXmlString(Encoding.ASCII.GetString(otherPublicKey))));
}
#endif
}
public static byte[] ECDHKeyExchange(Uri URL, string Endpoint = "")
{
byte[] key = default(byte[]);
using (ECDiffieHellmanCng AsymAlgo = new ECDiffieHellmanCng())
{
var publicKey = AsymAlgo.PublicKey.ToXmlString();
byte[] r = HttpPost(URL, Endpoint, Encoding.UTF8.GetBytes(publicKey));
ECDiffieHellmanCngPublicKey peerPublicKey = ECDiffieHellmanCngPublicKey.FromXmlString(Encoding.UTF8.GetString(r));
key = AsymAlgo.DeriveKeyMaterial(peerPublicKey);
}
return(key);
}
public static byte[] ECDHKeyExchange(Uri URL, byte[] PSK, string Endpoint = "")
{
byte[] key = default(byte[]);
using (ECDiffieHellmanCng AsymAlgo = new ECDiffieHellmanCng())
{
byte[] encryptedPublicKey = Encrypt(PSK, Encoding.UTF8.GetBytes(AsymAlgo.PublicKey.ToXmlString()));
byte[] r = Comms.HttpPost(URL, Endpoint, encryptedPublicKey);
string decryptedPeerPublicKey = Encoding.UTF8.GetString(Decrypt(PSK, r));
ECDiffieHellmanCngPublicKey peerPublicKey = ECDiffieHellmanCngPublicKey.FromXmlString(decryptedPeerPublicKey);
key = AsymAlgo.DeriveKeyMaterial(peerPublicKey);
}
return(key);
}
// TODO: Migrate to self implemented Diffie-Hellman Key Exchange
// ECDiffieHellmanCng is only available under Windows
public static byte[] KeyExchange(Uri url)
{
byte[] key = default;
using (ECDiffieHellmanCng AsymAlgo = new ECDiffieHellmanCng())
{
var publicKey = AsymAlgo.PublicKey.ToXmlString();
byte[] response = Http.Post(url, Encoding.UTF8.GetBytes(publicKey));
ECDiffieHellmanCngPublicKey peerPublicKey =
ECDiffieHellmanCngPublicKey.FromXmlString(Encoding.UTF8.GetString(response));
key = AsymAlgo.DeriveKeyMaterial(peerPublicKey);
}
return(key);
}
internal void DeriveKey(string otherPartyPublicKey)
{
aes = new RijndaelManaged();
aes.Padding = PaddingMode.PKCS7;
try
{
byte[] aesBytes = dh.DeriveKeyMaterial(ECDiffieHellmanCngPublicKey.FromXmlString(otherPartyPublicKey));
for (int i = 0; i < aes.Key.Length; ++i)
{
aes.Key[i] = aesBytes[i];
}
for (int i = 0; i < aes.IV.Length; ++i)
{
aes.IV[i] = aesBytes[i];
}
}
catch (Exception)
{
aes = null;
throw;
}
}
static public byte[] DiffieHellmanGetSecretKey(string publicKey, CngKey otherDFInstanceKey)
{
var df = new ECDiffieHellmanCng(otherDFInstanceKey);
return(df.DeriveKeyMaterial(ECDiffieHellmanCngPublicKey.FromXmlString(publicKey)));
}
