private void LookForHeaderBlock()
{
byte[] lengthBytes = new byte[sizeof(Int32)];
if (!_inputStream.ReadExact(lengthBytes))
{
CurrentItemType = AxCryptItemType.EndOfStream;
return;
}
Int32 headerBlockLength = BitConverter.ToInt32(lengthBytes, 0) - 5;
if (headerBlockLength < 0 || headerBlockLength > 0xfffff)
{
throw new FileFormatException("Invalid headerBlockLength {0}".InvariantFormat(headerBlockLength), ErrorStatus.FileFormatError);
}
int blockType = _inputStream.ReadByte();
if (blockType > 127)
{
throw new FileFormatException("Invalid block type {0}".InvariantFormat(blockType), ErrorStatus.FileFormatError);
}
HeaderBlockType headerBlockType = (HeaderBlockType)blockType;
byte[] dataBLock = new byte[headerBlockLength];
if (!_inputStream.ReadExact(dataBLock))
{
CurrentItemType = AxCryptItemType.EndOfStream;
return;
}
ParseHeaderBlock(headerBlockType, dataBLock);
DataHeaderBlock dataHeaderBlock = CurrentHeaderBlock as DataHeaderBlock;
if (dataHeaderBlock != null)
{
CurrentItemType = AxCryptItemType.Data;
}
}
private bool VerifyInternalUnsafe()
{
if (!_inputStream.Locate(_axCrypt1GuidBytes))
{
return(FailWithStatusReport("Not an AxCrypt file, No magic Guid was found."));
}
_statusReport.Add($"{nameof(AxCryptItemType.MagicGuid)} Ok with length {0}".InvariantFormat(AxCrypt1Guid.Length));
AxCryptVersion version = AxCryptVersion.Unknown;
ulong encryptedDataLength = 0;
int dataBlocks = 0;
while (true)
{
byte[] lengthBytes = new byte[sizeof(Int32)];
if (_inputStream.Read(lengthBytes, 0, lengthBytes.Length) != lengthBytes.Length)
{
return(FailWithStatusReport("End of stream reading header block length."));
}
int headerBlockLength = BitConverter.ToInt32(lengthBytes, 0) - 5;
int blockType = _inputStream.ReadByte();
if (blockType > 127 || blockType < 0)
{
return(FailWithStatusReport($"Unexpected header block type {blockType}"));
}
if (headerBlockLength < 0)
{
return(FailWithStatusReport($"Invalid block length {headerBlockLength}."));
}
byte[] dataBlock = new byte[headerBlockLength];
if (_inputStream.Read(dataBlock, 0, headerBlockLength) != dataBlock.Length)
{
return(FailWithStatusReport($"End of stream reading block type {blockType}"));
}
HeaderBlockType headerBlockType = (HeaderBlockType)blockType;
if (headerBlockType == HeaderBlockType.Data && version == AxCryptVersion.Version1)
{
return(ProcessVersion1DataBlock(dataBlock));
}
if (headerBlockType != HeaderBlockType.EncryptedDataPart && dataBlocks > 0)
{
_statusReport.Add($"{HeaderBlockType.EncryptedDataPart} Ok with {dataBlocks} blocks and the total length {encryptedDataLength}.");
dataBlocks = 0;
encryptedDataLength = 0;
}
switch (headerBlockType)
{
case HeaderBlockType.Version:
VersionHeaderBlock versionHeaderBlock = new VersionHeaderBlock(dataBlock);
_statusReport.Add($"AxCrypt version {versionHeaderBlock.VersionMajor}.{versionHeaderBlock.VersionMinor}.{versionHeaderBlock.VersionMinuscule}. File format version {versionHeaderBlock.FileVersionMajor}.{versionHeaderBlock.FileVersionMinor}.");
version = versionHeaderBlock.VersionMajor >= 2 ? AxCryptVersion.Version2 : AxCryptVersion.Version1;
break;
case HeaderBlockType.EncryptedDataPart:
switch (version)
{
case AxCryptVersion.Version2:
++dataBlocks;
encryptedDataLength += (uint)dataBlock.Length;
break;
case AxCryptVersion.Unknown:
default:
return(FailWithStatusReport($"{blockType} found but no {HeaderBlockType.Version} seen."));
}
break;
default:
_statusReport.Add($"{headerBlockType} Ok with length {headerBlockLength}");
break;
}
if (headerBlockType == HeaderBlockType.V2Hmac)
{
return(ShowStatusReport());
}
}
}