public void Initialize(DerivedBytesProvider derivedBytesProvider, Action <Dictionary <string, byte[]> > afterHeaderRead = null)
{
if (derivedBytesProvider == null)
{
throw new ArgumentNullException(nameof(derivedBytesProvider));
}
//header
//FileDesignator (8 bytes) + passwordSalt (32 bytes) + hmac salt (32 bytes) + iv (32 bytes)
FileHeader header = new FileHeader();
StreamRead(streamIn, header.fileDesignator);
StreamRead(streamIn, header.passwordSalt);
StreamRead(streamIn, header.hmacSalt);
StreamRead(streamIn, header.iv);
StreamRead(streamIn, header.headerAuthnDisk);
afterHeaderRead?.Invoke(header.ToDictionary());
FileVersion = HelixFileVersion.GetVersion(header.fileDesignator);
if (FileVersion == null)
{
throw new FileDesignatorException("Invalid file format, file designator not correct");
}
DerivedBytes = derivedBytesProvider.GetDerivedBytes(header.passwordSalt, FileVersion.DerivedBytesIterations);
byte[] headerBytes = header.GetBytesToHash();
byte[] hmacFullKey = ByteBlock.ConcatenateBytes(header.hmacSalt, DerivedBytes.Key);
hmacHash = new HMACSHA256(hmacFullKey);
//Validate Header HMAC
byte[] headerAuthnComputed = hmacHash.ComputeHash(headerBytes);
if (!ByteBlock.Equals(header.headerAuthnDisk, headerAuthnComputed))
{
throw new HMACAuthenticationException("Header HMAC Authentication Failed");
}
hmacTransform = new HMACDecrypt(headerAuthnComputed, hmacHash);
hmacStream = new CryptoStream2(streamIn, hmacTransform, CryptoStreamMode.Read);
aesTransform = Aes.Create();
aesTransform.KeySize = 256;
aesTransform.BlockSize = 128;
aesTransform.Mode = CipherMode.CBC;
aesTransform.Padding = PaddingMode.PKCS7;
aesTransform.IV = header.iv;
aesTransform.Key = DerivedBytes.Key;
aesStream = new CryptoStream2(hmacStream, aesTransform.CreateDecryptor(), CryptoStreamMode.Read);
gzipStream = new GZipStream(aesStream, CompressionMode.Decompress, true);
initialized = true;
}
public AuthenticatedEncryptor(Stream streamOut, DerivedBytes derivedBytes, HelixFileVersion hxVersion, byte[] hmacSalt = null, byte[] iv = null)
{
if (derivedBytes == null)
{
throw new ArgumentNullException(nameof(derivedBytes));
}
if (hxVersion == null)
{
throw new ArgumentNullException(nameof(hxVersion));
}
if (hmacSalt != null && hmacSalt.Length != HelixConsts.HMACSaltSize)
{
throw new ArgumentOutOfRangeException(nameof(hmacSalt));
}
if (iv != null && iv.Length != HelixConsts.IVSize)
{
throw new ArgumentOutOfRangeException(nameof(iv));
}
using (var random = RandomNumberGenerator.Create())
{
if (hmacSalt == null)
{
hmacSalt = new byte[HelixConsts.HMACSaltSize];
random.GetBytes(hmacSalt);
}
if (iv == null)
{
iv = new byte[HelixConsts.IVSize];
random.GetBytes(iv);
}
}
FileHeader header = new FileHeader
{
fileDesignator = hxVersion.FileDesignator,
passwordSalt = derivedBytes.Salt,
hmacSalt = hmacSalt,
iv = iv,
};
byte[] hmacFullKey = ByteBlock.ConcatenateBytes(hmacSalt, derivedBytes.Key);
this.streamOut = streamOut ?? throw new ArgumentNullException(nameof(streamOut));
byte[] bytesToHash = header.GetBytesToHash();
streamOut.Write(bytesToHash, 0, bytesToHash.Length);
hmacHash = new HMACSHA256(hmacFullKey);
header.headerAuthnDisk = hmacHash.ComputeHash(header.GetBytesToHash());
streamOut.Write(header.headerAuthnDisk, 0, header.headerAuthnDisk.Length);
hmacTransform = new HMACEncrypt(header.headerAuthnDisk, hmacHash);
hmacStream = new CryptoStream(streamOut, hmacTransform, CryptoStreamMode.Write);
aesTransform = Aes.Create();
aesTransform.KeySize = 256;
aesTransform.BlockSize = 128;
aesTransform.Mode = CipherMode.CBC;
aesTransform.Padding = PaddingMode.PKCS7;
aesTransform.IV = iv;
aesTransform.Key = derivedBytes.Key;
aesStream = new CryptoStream(hmacStream, aesTransform.CreateEncryptor(), CryptoStreamMode.Write);
gzipStream = new GZipStream(aesStream, CompressionMode.Compress, true);
}
public byte[] GetBytesToHash()
{
return(ByteBlock.ConcatenateBytes(fileDesignator, passwordSalt, hmacSalt, iv));
}