public void Test_Decrypt_Fails_ThrowsCryptographicException(Type cipherType)
{
using (var key = XChaChaKey.Generate())
{
var cipher = (XChaChaSecretKeyCipher)Activator.CreateInstance(cipherType);
var nonce = XChaChaNonce.Generate();
const int messageLength = 1024 * 1024;
var message = RandomBytesGenerator.NextBytes(messageLength);
var ciphertext = new byte[cipher.GetCipherTextLength(message.Length)];
cipher.Encrypt(message, ciphertext, key, nonce);
Action action = () =>
{
var wrongNonce = XChaChaNonce.Generate();
cipher.Decrypt(ciphertext, ciphertext, key, wrongNonce);
};
var exception = Assert.Throws <CryptographicException>(action);
Assert.Equal("decryption failed", exception.Message);
}
}
/// <summary>
/// Creates a new instance.
/// </summary>
/// <param name="stream">When encrypting, the stream to write the ciphertext to. When decrypting, the stream to read the ciphertext from.</param>
/// <param name="key">The encryption key.</param>
/// <param name="encryptionMode">Whether the stream will be used for encryption or decryption.</param>
/// <param name="leaveOpen">Whether to leave the <paramref name="stream"/> open.</param>
public XChaChaStream(Stream stream, XChaChaKey key, EncryptionMode encryptionMode, bool leaveOpen = false)
: base(stream, key, encryptionMode, leaveOpen)
{
}
/// <summary>
/// Encrypts the <paramref name="message"/> and writes computed ciphertext to <paramref name="ciphertext"/>.
/// </summary>
/// <param name="message">The message to encrypt.</param>
/// <param name="ciphertext">The buffer in which to write the ciphertext.</param>
/// <param name="key">The encryption key.</param>
/// <param name="nonce">The nonce to use when encrypting the <paramref name="message"/>.</param>
public void Encrypt(ReadOnlySpan <byte> message, Span <byte> ciphertext, XChaChaKey key, XChaChaNonce nonce)
{
this.InternalEncrypt(message, ciphertext, key, nonce);
}
/// <summary>
/// Decrypts the <paramref name="ciphertext"/>, verifies the authenticaion tag, and if successful,
/// writes the output to <paramref name="message"/>.
/// </summary>
/// <param name="ciphertext">The ciphertext to decrypt.</param>
/// <param name="message">The buffer in which to write the decrypted message.</param>
/// <param name="key">The encryption key.</param>
/// <param name="nonce">The nonce to use when decrypting the <paramref name="ciphertext"/>.</param>
public void Decrypt(ReadOnlySpan <byte> ciphertext, Span <byte> message, XChaChaKey key, XChaChaNonce nonce)
{
this.InternalDecrypt(ciphertext, message, key, nonce);
}
private protected abstract void InternalDecrypt(
ReadOnlySpan <byte> ciphertext,
Span <byte> message,
XChaChaKey key,
XChaChaNonce nonce);