private void WriteSafeBlock()
{
byte[] pbBlockIndex = MemUtil.UInt64ToBytes(m_uBlockIndex);
int cbBlockSize = m_iBufferPos;
byte[] pbBlockSize = MemUtil.Int32ToBytes(cbBlockSize);
byte[] pbBlockHmac;
byte[] pbBlockKey = GetHmacKey64(m_pbKey, m_uBlockIndex);
using (HMACSHA256 h = new HMACSHA256(pbBlockKey))
{
h.TransformBlock(pbBlockIndex, 0, pbBlockIndex.Length,
pbBlockIndex, 0);
h.TransformBlock(pbBlockSize, 0, pbBlockSize.Length,
pbBlockSize, 0);
if (cbBlockSize > 0)
{
h.TransformBlock(m_pbBuffer, 0, cbBlockSize, m_pbBuffer, 0);
}
h.TransformFinalBlock(MemUtil.EmptyByteArray, 0, 0);
pbBlockHmac = h.Hash;
}
MemUtil.ZeroByteArray(pbBlockKey);
MemUtil.Write(m_sBase, pbBlockHmac);
// MemUtil.Write(m_sBase, pbBlockIndex); // Implicit
MemUtil.Write(m_sBase, pbBlockSize);
if (cbBlockSize > 0)
{
m_sBase.Write(m_pbBuffer, 0, cbBlockSize);
}
++m_uBlockIndex;
m_iBufferPos = 0;
}
private bool ReadSafeBlock()
{
if (m_bEos)
{
return(false); // End of stream reached already
}
byte[] pbStoredHmac = MemUtil.Read(m_sBase, 32);
if ((pbStoredHmac == null) || (pbStoredHmac.Length != 32))
{
throw new EndOfStreamException(KLRes.FileCorrupted + " " +
KLRes.FileIncomplete);
}
// Block index is implicit: it's used in the HMAC computation,
// but does not need to be stored
// byte[] pbBlockIndex = MemUtil.Read(m_sBase, 8);
// if((pbBlockIndex == null) || (pbBlockIndex.Length != 8))
// throw new EndOfStreamException();
// ulong uBlockIndex = MemUtil.BytesToUInt64(pbBlockIndex);
// if((uBlockIndex != m_uBlockIndex) && m_bVerify)
// throw new InvalidDataException();
byte[] pbBlockIndex = MemUtil.UInt64ToBytes(m_uBlockIndex);
byte[] pbBlockSize = MemUtil.Read(m_sBase, 4);
if ((pbBlockSize == null) || (pbBlockSize.Length != 4))
{
throw new EndOfStreamException(KLRes.FileCorrupted + " " +
KLRes.FileIncomplete);
}
int nBlockSize = MemUtil.BytesToInt32(pbBlockSize);
if (nBlockSize < 0)
{
throw new InvalidDataException(KLRes.FileCorrupted);
}
m_iBufferPos = 0;
m_pbBuffer = MemUtil.Read(m_sBase, nBlockSize);
if ((m_pbBuffer == null) || ((m_pbBuffer.Length != nBlockSize) && m_bVerify))
{
throw new EndOfStreamException(KLRes.FileCorrupted + " " +
KLRes.FileIncompleteExpc);
}
if (m_bVerify)
{
byte[] pbCmpHmac;
byte[] pbBlockKey = GetHmacKey64(m_pbKey, m_uBlockIndex);
using (HMACSHA256 h = new HMACSHA256(pbBlockKey))
{
h.TransformBlock(pbBlockIndex, 0, pbBlockIndex.Length,
pbBlockIndex, 0);
h.TransformBlock(pbBlockSize, 0, pbBlockSize.Length,
pbBlockSize, 0);
if (m_pbBuffer.Length > 0)
{
h.TransformBlock(m_pbBuffer, 0, m_pbBuffer.Length,
m_pbBuffer, 0);
}
h.TransformFinalBlock(MemUtil.EmptyByteArray, 0, 0);
pbCmpHmac = h.Hash;
}
MemUtil.ZeroByteArray(pbBlockKey);
if (!MemUtil.ArraysEqual(pbCmpHmac, pbStoredHmac))
{
throw new InvalidDataException(KLRes.FileCorrupted);
}
}
++m_uBlockIndex;
if (nBlockSize == 0)
{
m_bEos = true;
return(false); // No further data available
}
return(true);
}
