static void example_kem()
{
Console.WriteLine("Starting KEM example");
// get the list of enabled KEM mechanisms
Console.WriteLine("Enabled KEM mechanisms: ");
foreach (string alg in KEM.EnabledMechanisms)
{
Console.WriteLine(" - " + alg);
}
// Instantiate the client and server
using (KEM client = new KEM("Kyber512"),
server = new KEM("Kyber512"))
{
Console.WriteLine("Perform key exchange with Kyber512 mechanism");
// Print out some info about the mechanism
Console.WriteLine("Mechanism details:");
Console.WriteLine(" - Alg name: " + client.AlgorithmName);
Console.WriteLine(" - Alg version: " + client.AlgorithmVersion);
Console.WriteLine(" - Claimed NIST level: " + client.ClaimedNistLevel);
Console.WriteLine(" - Is IND-CCA?: " + client.IsIndCCA);
Console.WriteLine(" - Secret key length: " + client.SecretKeyLength);
Console.WriteLine(" - Public key length: " + client.PublicKeyLength);
Console.WriteLine(" - Ciphertext length: " + client.CiphertextLength);
Console.WriteLine(" - Shared secret length: " + client.SharedSecretLength);
// Generate the client's key pair
byte[] public_key;
byte[] secret_key;
client.keypair(out public_key, out secret_key);
// The client sends the public key to the server
// The server generates and encapsulates the shared secret
byte[] ciphertext;
byte[] server_shared_secret;
server.encaps(out ciphertext, out server_shared_secret, public_key);
// The server sends the ciphertext to the client
// The client decapsulates the shared secret
byte[] client_shared_secret;
client.decaps(out client_shared_secret, ciphertext, secret_key);
// The client and server now share a secret. Let's make sure it matches.
if (server_shared_secret.SequenceEqual(client_shared_secret))
{
Console.WriteLine("KEM completed successfully");
Console.WriteLine();
}
else
{
Console.WriteLine("Error: shared secrets do not match!");
}
}
}
public async Task <ClientSharedSecret> DecapsulateSharedSecret([FromBody] SecretKey secretKey)
{
// The client decapsulates the shared secret
byte[] clientSharedSecret;
using (KEM client = new KEM(secretKey.KeyMechanism))
{
byte[] secret_key;
client.decaps(out clientSharedSecret, secretKey.CipherText, secretKey.Key);
return(new ClientSharedSecret()
{
SharedSecret = clientSharedSecret
});
}
}
private static void TestKEM(string kemAlg)
{
byte[] public_key;
byte[] secret_key;
byte[] ciphertext;
byte[] shared_secret_1;
byte[] shared_secret_2;
Random random = new Random();
// successful case
KEM kem = new KEM(kemAlg);
if (kemAlg != "DEFAULT")
{
Assert.AreEqual(kem.AlgorithmName, kemAlg);
}
Assert.IsTrue(kem.IsUsable, "IsUsable after constructor");
kem.keypair(out public_key, out secret_key);
log("public_key: " + BytesToHex(public_key));
log("secret_key: " + BytesToHex(secret_key));
Assert.IsTrue((UInt64)public_key.Length <= kem.PublicKeyLength, "public key length");
Assert.IsTrue((UInt64)secret_key.Length <= kem.SecretKeyLength, "secret key length");
kem.encaps(out ciphertext, out shared_secret_1, public_key);
log("ciphertext: " + BytesToHex(ciphertext));
log("shared_secret_1: " + BytesToHex(shared_secret_1));
Assert.IsTrue((UInt64)ciphertext.Length <= kem.CiphertextLength, "ciphertext length");
Assert.IsTrue((UInt64)shared_secret_1.Length <= kem.SharedSecretLength, "shared secret length");
kem.decaps(out shared_secret_2, ciphertext, secret_key);
log("shared_secret_2: " + BytesToHex(shared_secret_2));
Assert.IsTrue(shared_secret_1.SequenceEqual(shared_secret_2), "shared secrets are not equal");
// failure cases
// wrong ciphertext
byte[] wrong_ciphertext = new byte[ciphertext.Length];
random.NextBytes(wrong_ciphertext);
log("wrong_ciphertext: " + BytesToHex(wrong_ciphertext));
try {
kem.decaps(out shared_secret_2, wrong_ciphertext, secret_key);
// if the wrong value didn't trigger an exception, make sure the shared secret do not match
Assert.IsFalse(shared_secret_1.SequenceEqual(shared_secret_2), "wrong ciphertext, shared secrets should have been different");
}
catch (OQSException)
{
// exception expected
}
// wrong secret key
byte[] wrong_secret_key = new byte[secret_key.Length];
random.NextBytes(wrong_secret_key);
log("wrong_secret_key: " + BytesToHex(wrong_secret_key));
try
{
kem.decaps(out shared_secret_2, ciphertext, wrong_secret_key);
// if the wrong value didn't trigger an exception, make sure the shared secret do not match
Assert.IsFalse(shared_secret_1.SequenceEqual(shared_secret_2), "wrong ciphertext, shared secrets should have been different");
}
catch (OQSException)
{
// exception expected
}
// clean-up
kem.Dispose();
Assert.IsFalse(kem.IsUsable, "IsUsable after cleanup");
}