// The Main function of the program
static void Main(string[] args)
{
// Initializes the Stopwatch used for time meassurements concerning the keyExchange. This stopwatch will be stopped at severel points, for example before printing text.
Stopwatch SWForDHKE = new Stopwatch();
for (int p = 0; p < 500; p++)
{
SWForDHKE.Start();
// Decleration of the variables used by Person1 and Person2
Byte[] Person1PublicKey;
Byte[] Person2PublicKey;
Byte[] Person1SharedKey;
Byte[] Person2SharedKey;
SWForDHKE.Stop();
// Initializes the Stopwatch used for time meassurements concerning keyGeneration.
Stopwatch SWForKeyGenration = new Stopwatch();
// Initialization of the Keysize for both the public and private keys
int keySize = 521;
SWForDHKE.Start();
// Sets the secret message that is going to be encrypted and decrypted by respectively Person1 and Person2
String secretMessage = "The secret message";
SWForDHKE.Stop();
SWForDHKE.Start();
// Starts the timer so we can see how long it takes for to genrate a random keyPair
SWForKeyGenration.Start();
// Creates a CNG (Cryptography Next Genration) implimentiation of the ECDH (Elliptic Curve Diffie-Hellman) algorithm for Person1 with a randomly generated keyPair consisting of both a public and a private key
using (ECDiffieHellmanCng ECDHCNGForPerson1 = new ECDiffieHellmanCng(keySize))
{
// Stops the timer, as the keys have now been generated
SWForKeyGenration.Stop();
SWForDHKE.Stop();
// Prints the time it took to generate the random keyPair
Write("It took " + SWForKeyGenration.ElapsedMilliseconds + " milliseconds to generate a random key pair." + Environment.NewLine);
Write("It took " + SWForKeyGenration.ElapsedTicks + " ticks to generate a random key pair." + Environment.NewLine + Environment.NewLine);
// Prints Person1s private key, which is printed in a big-endian format
Write("Person 1s private key is: ");
foreach (Byte b in ECDHCNGForPerson1.ExportExplicitParameters(true).D)
{
Write($"{b} ");
}
Write(Environment.NewLine + Environment.NewLine);
SWForDHKE.Start();
// Sets the method used for deriving the different shared keys as an ECDH-hash-function
ECDHCNGForPerson1.KeyDerivationFunction = ECDiffieHellmanKeyDerivationFunction.Hash;
// Sets the hashing algorithm used as the Sha256 algorithm
ECDHCNGForPerson1.HashAlgorithm = CngAlgorithm.Sha256;
// Sets Person1s public key as the public key generated by the ECDHCNG for Person1
Person1PublicKey = ECDHCNGForPerson1.PublicKey.ToByteArray();
SWForDHKE.Stop();
// Prints the contents of Person1s public key
Write("Person 1s public key is: " + Environment.NewLine);
foreach (Byte b in Person1PublicKey)
{
Write($"{b} ");
}
Write(Environment.NewLine + Environment.NewLine);
SWForDHKE.Start();
// Creates a CNG (Cryptography Next Genration) implimentiation of the ECDH (Elliptic Curve Diffie-Hellman) algorithm for Person2 with a randomly generated keyPair consisting of both a public and a private key
using (ECDiffieHellmanCng ECDHCNGForPerson2 = new ECDiffieHellmanCng(keySize))
{
SWForDHKE.Stop();
// Prints Person2s private key, which is printed in a big-endian format
Write("Person 2s private key is: ");
foreach (Byte b in ECDHCNGForPerson2.ExportExplicitParameters(true).D)
{
Write($"{b} ");
}
Write(Environment.NewLine + Environment.NewLine);
// Sets the method used for deriving the different shared keys as an ECDH-hash-function
ECDHCNGForPerson2.KeyDerivationFunction = ECDiffieHellmanKeyDerivationFunction.Hash;
// Sets the hashing algorithm used as the Sha256 algorithm
ECDHCNGForPerson2.HashAlgorithm = CngAlgorithm.Sha256;
// Sets Person2s public key as the public key generated by the ECDHCNG for Person2
Person2PublicKey = ECDHCNGForPerson2.PublicKey.ToByteArray();
SWForDHKE.Stop();
// Prints the contents of Person2s public key
Write("Person 2s public key is: " + Environment.NewLine);
foreach (Byte b in Person2PublicKey)
{
Write($"{b} ");
}
Write(Environment.NewLine + Environment.NewLine);
SWForDHKE.Start();
// Sets the key used for deriving the shared key to the contents of Person1s public key, and this is used by Person1
CngKey k2 = CngKey.Import(Person1PublicKey, CngKeyBlobFormat.EccPublicBlob);
// Creates the shared key that Person2 uses to the shared key derived from a key exchange
Person2SharedKey = ECDHCNGForPerson2.DeriveKeyMaterial(k2);
}
// Sets the key used for deriving the shared key to the contents of Person2s public key, and this is used by Person1
CngKey k1 = CngKey.Import(Person2PublicKey, CngKeyBlobFormat.EccPublicBlob);
// Creates the shared key that Person1 uses to the shared key derived from a key exchange
Person1SharedKey = ECDHCNGForPerson1.DeriveKeyMaterial(k1);
SWForDHKE.Stop();
// Prints the contents of both shared keys
Write("Person 1s shared key is: " + Environment.NewLine);
foreach (Byte b in Person1SharedKey)
{
Write($"{b} ");
}
Write(Environment.NewLine + Environment.NewLine);
Write("Person 2s shared key is: " + Environment.NewLine);
foreach (Byte b in Person2SharedKey)
{
Write($"{b} ");
}
Write(Environment.NewLine + Environment.NewLine);
SWForDHKE.Start();
// Sends the secret message from Person1 using Person1s shared key to Person2
Send(Person1SharedKey, secretMessage, out Byte[] encryptedMessage, out Byte[] IV);