public void ReadFrom_InvalidInputs()
{
ExceptionAssert.Throws <ArgumentNullException>(
() => CryptoStream.ReadFrom(null, new MockCryptoTransform(5)));
ExceptionAssert.Throws <ArgumentException>(
() => CryptoStream.ReadFrom(Stream.Null));
ExceptionAssert.Throws <ArgumentException>(
() => CryptoStream.ReadFrom(Stream.Null, null));
}
public void ReadFrom()
{
var t1 = new MockCryptoTransform(6);
var t2 = new MockCryptoTransform(9);
var ms = new MemoryStream(Encoding.UTF8.GetBytes("abcdefghijkl"));
using (var cryptoStream = CryptoStream.ReadFrom(ms, t1, t2))
{
var buffer = new byte[100];
int bytesRead = cryptoStream.Read(buffer, 0, 100);
Assert.AreEqual("--abcdef-g_hijkl_ZZ", Encoding.UTF8.GetString(buffer, 0, bytesRead));
}
}
private static async Task PlayBobRoleAsync(ICryptographicKey ownSigningKey, ICryptographicKey othersSigningPublicKey, Stream channel, CancellationToken cancellationToken)
{
// Create ephemeral ECDH key pair, to prepare for the symmetric encryption key exchange.
using (IECDiffieHellman? ecdhKeyPair = NetFxCrypto.ECDiffieHellman.Create())
{
// Send the ephemeral ECDH public key to Alice.
var ecdhPublicKey = ecdhKeyPair.PublicKey.ToByteArray();
await WriteAsync(channel, ecdhPublicKey, cancellationToken);
// Authenticate to Alice that this is really Bob's ephemeral public key.
byte[] ecdhPublicKeySignature = WinRTCrypto.CryptographicEngine.Sign(ownSigningKey, ecdhPublicKey);
await WriteAsync(channel, ecdhPublicKeySignature, cancellationToken);
// Read Alice's reply. It consists of her own ephemeral public key and signature.
byte[] alicePublicDH = await ReadAsync(channel, cancellationToken);
byte[] aliceSignedDH = await ReadAsync(channel, cancellationToken);
// Authenticate Alice's public key.
Assert.True(WinRTCrypto.CryptographicEngine.VerifySignature(othersSigningPublicKey, alicePublicDH, aliceSignedDH));
// Deserialize Alice's public key and derive the shared secret from it.
IECDiffieHellmanPublicKey?aliceDHPK = NetFxCrypto.ECDiffieHellmanCngPublicKey.FromByteArray(alicePublicDH);
byte[] encryptionKeyMaterial = ecdhKeyPair.DeriveKeyMaterial(aliceDHPK);
ICryptographicKey?encryptionKey = WinRTCrypto.SymmetricKeyAlgorithmProvider.OpenAlgorithm(SymmetricAlgorithm.AesCbcPkcs7)
.CreateSymmetricKey(encryptionKeyMaterial);
// Bob reads Alice's secret message using the shared secret that both parties derived,
// but never transmitted.
using (var aes = CryptoStream.ReadFrom(channel, WinRTCrypto.CryptographicEngine.CreateDecryptor(encryptionKey)))
{
byte[] plaintext = await ReadAsync(aes, cancellationToken);
// Assert that the plaintext is as it was expected to be.
Assert.Equal(
Convert.ToBase64String(SecretMessage),
Convert.ToBase64String(plaintext));
}
channel.Dispose();
}
}