/// <summary>
/// Encrypt a stream with a given set of headers and write to an output stream. The caller is responsible for consistency and completeness
/// of the headers. Headers that are not known until encryption and compression are added here.
/// </summary>
/// <param name="outputDocumentHeaders"></param>
/// <param name="inputStream"></param>
/// <param name="outputStream"></param>
public void EncryptTo(DocumentHeaders outputDocumentHeaders, Stream inputStream, Stream outputStream, AxCryptOptions options, ProgressContext progress)
{
if (outputDocumentHeaders == null)
{
throw new ArgumentNullException("outputDocumentHeaders");
}
if (inputStream == null)
{
throw new ArgumentNullException("inputStream");
}
if (outputStream == null)
{
throw new ArgumentNullException("outputStream");
}
if (progress == null)
{
throw new ArgumentNullException("progress");
}
if (!outputStream.CanSeek)
{
throw new ArgumentException("The output stream must support seek in order to back-track and write the HMAC.");
}
if (options.HasMask(AxCryptOptions.EncryptWithCompression) && options.HasMask(AxCryptOptions.EncryptWithoutCompression))
{
throw new ArgumentException("Invalid options, cannot specify both with and without compression.");
}
if (!options.HasMask(AxCryptOptions.EncryptWithCompression) && !options.HasMask(AxCryptOptions.EncryptWithoutCompression))
{
throw new ArgumentException("Invalid options, must specify either with or without compression.");
}
bool isCompressed = options.HasMask(AxCryptOptions.EncryptWithCompression);
outputDocumentHeaders.IsCompressed = isCompressed;
outputDocumentHeaders.WriteWithoutHmac(outputStream);
using (ICryptoTransform encryptor = DataCrypto.CreateEncryptingTransform())
{
long outputStartPosition = outputStream.Position;
using (CryptoStream encryptingStream = new CryptoStream(new NonClosingStream(outputStream), encryptor, CryptoStreamMode.Write))
{
if (isCompressed)
{
EncryptWithCompressionInternal(outputDocumentHeaders, inputStream, encryptingStream, progress);
}
else
{
outputDocumentHeaders.PlaintextLength = CopyToWithCount(inputStream, encryptingStream, progress);
}
}
outputStream.Flush();
outputDocumentHeaders.CipherTextLength = outputStream.Position - outputStartPosition;
using (HmacStream outputHmacStream = new HmacStream(outputDocumentHeaders.HmacSubkey.Key, outputStream))
{
outputDocumentHeaders.WriteWithHmac(outputHmacStream);
outputHmacStream.ReadFrom(outputStream);
outputDocumentHeaders.Hmac = outputHmacStream.HmacResult;
}
// Rewind and rewrite the headers, now with the updated HMAC
outputDocumentHeaders.WriteWithoutHmac(outputStream);
outputStream.Position = outputStream.Length;
}
}
public static void TestHmacStream()
{
Assert.Throws<ArgumentNullException>(() =>
{
using (HmacStream hmacStream = new HmacStream(null)) { }
});
AesKey key = new AesKey(new byte[16]);
using (HmacStream hmacStream = new HmacStream(key))
{
Assert.That(hmacStream.CanRead, Is.False, "HmacStream does not support reading.");
Assert.That(hmacStream.CanSeek, Is.False, "HmacStream does not support seeking.");
Assert.That(hmacStream.CanWrite, Is.True, "HmacStream does support writing.");
Assert.Throws<NotSupportedException>(() =>
{
byte[] buffer = new byte[5];
hmacStream.Read(buffer, 0, buffer.Length);
});
Assert.Throws<NotSupportedException>(() =>
{
hmacStream.Seek(0, SeekOrigin.Begin);
});
Assert.Throws<NotSupportedException>(() =>
{
hmacStream.SetLength(0);
});
Assert.Throws<ArgumentNullException>(() =>
{
hmacStream.ReadFrom(null);
});
hmacStream.Write(new byte[10], 0, 10);
using (Stream dataStream = new MemoryStream())
{
dataStream.Write(new byte[10], 0, 10);
dataStream.Position = 0;
hmacStream.ReadFrom(dataStream);
}
Assert.That(hmacStream.Position, Is.EqualTo(20), "There are 20 bytes written so the position should be 20.");
Assert.That(hmacStream.Length, Is.EqualTo(20), "There are 20 bytes written so the position should be 20.");
hmacStream.Flush();
Assert.That(hmacStream.Position, Is.EqualTo(20), "Nothing should change after Flush(), this is not a buffered stream.");
Assert.That(hmacStream.Length, Is.EqualTo(20), "Nothing should change after Flush(), this is not a buffered stream.");
Assert.Throws<NotSupportedException>(() =>
{
hmacStream.Position = 0;
}, "Position is not supported.");
DataHmac dataHmac = hmacStream.HmacResult;
Assert.That(dataHmac.GetBytes(), Is.EquivalentTo(new byte[] { 0x62, 0x6f, 0x2c, 0x61, 0xc7, 0x68, 0x00, 0xb3, 0xa6, 0x8d, 0xf9, 0x55, 0x95, 0xbc, 0x1f, 0xd1 }), "The HMAC of 20 bytes of zero with 128-bit AesKey all zero should be this.");
Assert.Throws<InvalidOperationException>(() =>
{
hmacStream.Write(new byte[1], 0, 1);
}, "Can't write to the stream after checking and thus finalizing the HMAC");
// This also implicitly covers double-dispose since we're in a using block.
hmacStream.Dispose();
Assert.Throws<ObjectDisposedException>(() =>
{
DataHmac invalidDataHmac = hmacStream.HmacResult;
// Remove FxCop warning
Object.Equals(invalidDataHmac, null);
});
Assert.Throws<ObjectDisposedException>(() =>
{
hmacStream.Write(new byte[1], 0, 1);
});
Assert.Throws<ObjectDisposedException>(() =>
{
using (Stream stream = new MemoryStream())
{
hmacStream.ReadFrom(stream);
}
});
}
}