public BlockReaderWriter(EncryptionSettings encryptionSettings, string key, Stream stream, int defaultBlockSize)
{
if (encryptionSettings == null)
{
throw new ArgumentNullException("encryptionSettings");
}
if (key == null)
{
throw new ArgumentNullException("key");
}
if (stream == null)
{
throw new ArgumentNullException("stream");
}
if (!stream.CanRead)
{
throw new ArgumentException("The Underlying stream for a BlockReaderWriter must always be either read-only or read-write. Write only streams are not supported.");
}
if (!stream.CanSeek)
{
throw new ArgumentException("The Underlying stream for a BlockReaderWriter must be seekable.");
}
isReadonly = !stream.CanWrite;
this.settings = encryptionSettings;
this.key = key;
this.stream = stream;
this.header = ReadOrWriteHeader(defaultBlockSize);
this.footer = ReadOrWriteFooter();
}
public BlockReaderWriter(EncryptionSettings encryptionSettings, string key, Stream stream, int defaultBlockSize)
{
if (encryptionSettings == null)
throw new ArgumentNullException("encryptionSettings");
if (key == null)
throw new ArgumentNullException("key");
if (stream == null)
throw new ArgumentNullException("stream");
if (!stream.CanRead)
throw new ArgumentException("The Underlying stream for a BlockReaderWriter must always be either read-only or read-write. Write only streams are not supported.");
if (!stream.CanSeek)
throw new ArgumentException("The Underlying stream for a BlockReaderWriter must be seekable.");
isReadonly = !stream.CanWrite;
this.settings = encryptionSettings;
this.key = key;
this.stream = stream;
this.header = ReadOrWriteEmptyHeader(defaultBlockSize);
this.footer = ReadOrWriteFooter();
totalUnencryptedSize = 0;
}
private EncryptedFile.Header ReadOrWriteEmptyHeader(int defaultBlockSize)
{
lock (locker)
{
stream.Position = 0;
if (stream.Length >= EncryptedFile.Header.HeaderSize)
{
// Read header
int headerSize;
var magicNumber = stream.ReadUInt64();
switch (magicNumber)
{
case EncryptedFile.DefaultMagicNumber: //old header struct --> without the last field
headerSize = EncryptedFile.Header.HeaderSize - Marshal.SizeOf(typeof(long));
break;
case EncryptedFile.WithTotalSizeMagicNumber:
headerSize = EncryptedFile.Header.HeaderSize;
break;
default:
throw new ApplicationException("Invalid magic number");
}
stream.Position = 0;
var headerBytes = stream.ReadEntireBlock(headerSize);
var fileHeader = StructConverter.ConvertBitsToStruct <EncryptedFile.Header>(headerBytes);
if (fileHeader.MagicNumber != EncryptedFile.DefaultMagicNumber && fileHeader.MagicNumber != EncryptedFile.WithTotalSizeMagicNumber)
{
throw new InvalidDataException("The magic number in the file doesn't match the expected magic number for encrypted files. Perhaps this file isn't encrypted?");
}
return(fileHeader);
}
else
{
// Write empty header
var sizeTest = settings.Codec.EncodeBlock("Dummy key", new byte[defaultBlockSize]);
var fileHeader = new EncryptedFile.Header
{
MagicNumber = EncryptedFile.WithTotalSizeMagicNumber,
DecryptedBlockSize = defaultBlockSize,
IVSize = sizeTest.IV.Length,
EncryptedBlockSize = sizeTest.Data.Length,
TotalUnencryptedSize = EncryptedFile.Header.HeaderSize + EncryptedFile.Footer.FooterSize
};
WriteHeaderInCurrentPositionIfNotReadonly(fileHeader);
return(fileHeader);
}
}
}
private void WriteHeaderInCurrentPositionIfNotReadonly(EncryptedFile.Header fileHeader)
{
if (isReadonly)
{
return;
}
var headerBytes = StructConverter.ConvertStructToBits(fileHeader);
stream.Write(headerBytes, 0, EncryptedFile.Header.HeaderSize);
}
private void WriteHeaderInCurrentPositionIfNotReadonly(EncryptedFile.Header fileHeader, ulong magicNumber)
{
if (isReadonly)
{
return;
}
var headerSize = GetHeaderSizeByMagicNumber(magicNumber);
var headerBytes = StructConverter.ConvertStructToBits(fileHeader, headerSize);
stream.Write(headerBytes, 0, headerSize);
}
private EncryptedFile.Header ReadOrWriteHeader(int defaultBlockSize)
{
lock (locker)
{
stream.Position = 0;
if (stream.Length >= EncryptedFile.Header.HeaderSize)
{
// Read header
var headerBytes = stream.ReadEntireBlock(EncryptedFile.Header.HeaderSize);
var header = StructConverter.ConvertBitsToStruct <EncryptedFile.Header>(headerBytes);
if (header.MagicNumber != EncryptedFile.DefaultMagicNumber)
{
throw new InvalidDataException("The magic number in the file doesn't match the expected magic number for encypted files. Perhaps this file isn't encrypted?");
}
return(header);
}
else
{
// Write header
var sizeTest = settings.Codec.EncodeBlock("Dummy key", new byte[defaultBlockSize]);
var header = new EncryptedFile.Header
{
MagicNumber = EncryptedFile.DefaultMagicNumber,
DecryptedBlockSize = defaultBlockSize,
IVSize = sizeTest.IV.Length,
EncryptedBlockSize = sizeTest.Data.Length
};
var headerBytes = StructConverter.ConvertStructToBits(header);
if (!isReadonly)
{
stream.Write(headerBytes, 0, EncryptedFile.Header.HeaderSize);
}
return(header);
}
}
}
private EncryptedFile.Header ReadOrWriteEmptyHeader(int defaultBlockSize)
{
lock (locker)
{
stream.Position = 0;
if (stream.Length >= EncryptedFile.Header.HeaderSize)
{
// Read header
var magicNumber = stream.ReadUInt64();
var headerSize = GetHeaderSizeByMagicNumber(magicNumber);
stream.Position = 0;
var headerBytes = stream.ReadEntireBlock(headerSize);
var fileHeader = StructConverter.ConvertBitsToStruct <EncryptedFile.Header>(headerBytes, headerSize);
if (fileHeader.MagicNumber != EncryptedFile.DefaultMagicNumber && fileHeader.MagicNumber != EncryptedFile.WithTotalSizeMagicNumber)
{
throw new InvalidDataException("The magic number in the file doesn't match the expected magic number for encrypted files. Perhaps this file isn't encrypted?");
}
return(fileHeader);
}
else
{
// Write empty header
var sizeTest = settings.Codec.EncodeBlock("Dummy key", new byte[defaultBlockSize]);
var fileHeader = new EncryptedFile.Header
{
MagicNumber = EncryptedFile.WithTotalSizeMagicNumber,
DecryptedBlockSize = defaultBlockSize,
IVSize = sizeTest.IV.Length,
EncryptedBlockSize = sizeTest.Data.Length,
TotalUnencryptedSize = 0
};
WriteHeaderInCurrentPositionIfNotReadonly(fileHeader, fileHeader.MagicNumber);
return(fileHeader);
}
}
}
private EncryptedFile.Header ReadOrWriteEmptyHeader(int defaultBlockSize)
{
lock (locker)
{
stream.Position = 0;
if (stream.Length >= EncryptedFile.Header.HeaderSize)
{
// Read header
var magicNumber = stream.ReadUInt64();
var headerSize = GetHeaderSizeByMagicNumber(magicNumber);
stream.Position = 0;
var headerBytes = stream.ReadEntireBlock(headerSize);
var fileHeader = StructConverter.ConvertBitsToStruct<EncryptedFile.Header>(headerBytes, headerSize);
if (fileHeader.MagicNumber != EncryptedFile.DefaultMagicNumber && fileHeader.MagicNumber != EncryptedFile.WithTotalSizeMagicNumber)
throw new InvalidDataException("The magic number in the file doesn't match the expected magic number for encrypted files. Perhaps this file isn't encrypted?");
return fileHeader;
}
else
{
// Write empty header
var sizeTest = settings.Codec.EncodeBlock("Dummy key", new byte[defaultBlockSize]);
var fileHeader = new EncryptedFile.Header
{
MagicNumber = EncryptedFile.WithTotalSizeMagicNumber,
DecryptedBlockSize = defaultBlockSize,
IVSize = sizeTest.IV.Length,
EncryptedBlockSize = sizeTest.Data.Length,
TotalUnencryptedSize = 0
};
WriteHeaderInCurrentPositionIfNotReadonly(fileHeader, fileHeader.MagicNumber);
return fileHeader;
}
}
}
private EncryptedFile.Header ReadOrWriteHeader(int defaultBlockSize)
{
lock (locker)
{
stream.Position = 0;
if (stream.Length >= EncryptedFile.Header.HeaderSize)
{
// Read header
var headerBytes = stream.ReadEntireBlock(EncryptedFile.Header.HeaderSize);
var header = StructConverter.ConvertBitsToStruct<EncryptedFile.Header>(headerBytes);
if (header.MagicNumber != EncryptedFile.DefaultMagicNumber)
throw new InvalidDataException("The magic number in the file doesn't match the expected magic number for encrypted files. Perhaps this file isn't encrypted?");
return header;
}
else
{
// Write header
var sizeTest = settings.Codec.EncodeBlock("Dummy key", new byte[defaultBlockSize]);
var header = new EncryptedFile.Header
{
MagicNumber = EncryptedFile.DefaultMagicNumber,
DecryptedBlockSize = defaultBlockSize,
IVSize = sizeTest.IV.Length,
EncryptedBlockSize = sizeTest.Data.Length
};
var headerBytes = StructConverter.ConvertStructToBits(header);
if (!isReadonly)
stream.Write(headerBytes, 0, EncryptedFile.Header.HeaderSize);
return header;
}
}
}
private EncryptedFile.Header ReadOrWriteEmptyHeader(int defaultBlockSize)
{
lock (locker)
{
stream.Position = 0;
if (stream.Length >= EncryptedFile.Header.HeaderSize)
{
// Read header
int headerSize;
var magicNumber = stream.ReadUInt64();
switch (magicNumber)
{
case EncryptedFile.DefaultMagicNumber: //old header struct --> without the last field
headerSize = EncryptedFile.Header.HeaderSize - Marshal.SizeOf(typeof(long));
break;
case EncryptedFile.WithTotalSizeMagicNumber:
headerSize = EncryptedFile.Header.HeaderSize;
break;
default:
throw new ApplicationException("Invalid magic number");
}
stream.Position = 0;
var headerBytes = stream.ReadEntireBlock(headerSize);
var fileHeader = StructConverter.ConvertBitsToStruct<EncryptedFile.Header>(headerBytes);
if (fileHeader.MagicNumber != EncryptedFile.DefaultMagicNumber && fileHeader.MagicNumber != EncryptedFile.WithTotalSizeMagicNumber)
throw new InvalidDataException("The magic number in the file doesn't match the expected magic number for encrypted files. Perhaps this file isn't encrypted?");
return fileHeader;
}
else
{
// Write empty header
var sizeTest = settings.Codec.EncodeBlock("Dummy key", new byte[defaultBlockSize]);
var fileHeader = new EncryptedFile.Header
{
MagicNumber = EncryptedFile.WithTotalSizeMagicNumber,
DecryptedBlockSize = defaultBlockSize,
IVSize = sizeTest.IV.Length,
EncryptedBlockSize = sizeTest.Data.Length,
TotalUnencryptedSize = EncryptedFile.Header.HeaderSize + EncryptedFile.Footer.FooterSize
};
WriteHeaderInCurrentPositionIfNotReadonly(fileHeader);
return fileHeader;
}
}
}
