private void SetContentKeyFromHeader(byte[] headerBytes)
{
var decryptedBytes = new byte[headerBytes.Length];
using (MemoryStream inStream = new MemoryStream(headerBytes))
{
using (CryptoStream decryptStream = new CryptoStream(inStream, HeaderCryptoProvider.CreateDecryptor(), CryptoStreamMode.Read))
{
if (decryptStream.Read(decryptedBytes, 0, decryptedBytes.Length) == decryptedBytes.Length)
{
var key = new byte[ContentCryptoProvder.Key.Length];
var iv = new byte[ContentCryptoProvder.IV.Length];
Array.ConstrainedCopy(decryptedBytes, GetKeyHeaderOffset(), key, 0, key.Length);
Array.ConstrainedCopy(decryptedBytes, GetIVHeaderOffset(), iv, 0, iv.Length);
ContentCryptoProvder.Key = key;
ContentCryptoProvder.IV = iv;
}
}
}
}
private byte[] GetEncryptedHeaderBytes()
{
var contentKeyBytes = GetClearHeader();
var encryptedContentKeyBytes = new byte[PasswordKeyHash.Length + HeaderCryptoProvider.IV.Length + contentKeyBytes.Length];
using (MemoryStream buffStream = new MemoryStream(encryptedContentKeyBytes))
{
//write the password hash to the buffer for password validation
buffStream.Write(PasswordKeyHash, 0, PasswordKeyHash.Length);
//write the header IV to the buffer for header decryption
buffStream.Write(HeaderCryptoProvider.IV, 0, HeaderCryptoProvider.IV.Length);
using (CryptoStream csEncrypt = new CryptoStream(buffStream, HeaderCryptoProvider.CreateEncryptor(), CryptoStreamMode.Write))
{
csEncrypt.Write(contentKeyBytes, 0, contentKeyBytes.Length);
}
}
return(encryptedContentKeyBytes);
}
