VeraCrypt/src/Volume/Keyfile.cpp

/*
 Derived from source code of TrueCrypt 7.1a, which is
 Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed
 by the TrueCrypt License 3.0.

 Modifications and additions to the original source code (contained in this file)
 and all other portions of this file are Copyright (c) 2013-2017 IDRIX
 and are governed by the Apache License 2.0 the full text of which is
 contained in the file License.txt included in VeraCrypt binary and source
 code distribution packages.
*/

#include "Platform/Serializer.h"
#include "Common/SecurityToken.h"
#include "Common/EMVToken.h"
#include "Crc32.h"
#include "Keyfile.h"
#include "VolumeException.h"
namespace VeraCrypt
{
	void Keyfile::Apply (const BufferPtr &pool, bool emvSupportEnabled) const
	{
		if (Path.IsDirectory())
			throw ParameterIncorrect (SRC_POS);

		File file;

		Crc32 crc32;
		size_t poolPos = 0;
		uint64 totalLength = 0;
		uint64 readLength;

		SecureBuffer keyfileBuf (File::GetOptimalReadSize());

		if (Token::IsKeyfilePathValid (Path, emvSupportEnabled))
		{
			// Apply keyfile generated by a security token
			vector <byte> keyfileData;
			Token::getTokenKeyfile(wstring(Path))->GetKeyfileData(keyfileData);

			if (keyfileData.size() < MinProcessedLength)
				throw InsufficientData(SRC_POS, Path);

			for (size_t i = 0; i < keyfileData.size(); i++)
			{
				uint32 crc = crc32.Process(keyfileData[i]);

				pool[poolPos++] += (byte)(crc >> 24);
				pool[poolPos++] += (byte)(crc >> 16);
				pool[poolPos++] += (byte)(crc >> 8);
				pool[poolPos++] += (byte) crc;

				if (poolPos >= pool.Size())
					poolPos = 0;

				if (++totalLength >= MaxProcessedLength)
					break;
			}


			burn(&keyfileData.front(), keyfileData.size());
			goto  done;
		}

		file.Open (Path, File::OpenRead, File::ShareRead);

		while ((readLength = file.Read (keyfileBuf)) > 0)
		{
			for (size_t i = 0; i < readLength; i++)
			{
				uint32 crc = crc32.Process(keyfileBuf[i]);
				pool[poolPos++] += (byte)(crc >> 24);
				pool[poolPos++] += (byte)(crc >> 16);
				pool[poolPos++] += (byte)(crc >> 8);
				pool[poolPos++] += (byte) crc;
				if (poolPos >= pool.Size())
					poolPos = 0;
				if (++totalLength >= MaxProcessedLength)
					goto done;
			}
		}
		done:

		if (totalLength < MinProcessedLength)
			throw InsufficientData (SRC_POS, Path);
	}

	shared_ptr <VolumePassword> Keyfile::ApplyListToPassword (shared_ptr <KeyfileList> keyfiles, shared_ptr <VolumePassword> password, bool emvSupportEnabled)
	{
		if (!password)
			password.reset (new VolumePassword);

		if (!keyfiles || keyfiles->size() < 1)
			return password;

		KeyfileList keyfilesExp;
		HiddenFileWasPresentInKeyfilePath = false;

		// Enumerate directories
		foreach (shared_ptr <Keyfile> keyfile, *keyfiles)
		{
			if (FilesystemPath (*keyfile).IsDirectory())
			{
				size_t keyfileCount = 0;
				foreach_ref (const FilePath &path, Directory::GetFilePaths (*keyfile))
				{
#ifdef TC_UNIX
					// Skip hidden files
					if (wstring (path.ToBaseName()).find (L'.') == 0)
					{
						HiddenFileWasPresentInKeyfilePath = true;
						continue;
					}
#endif
					keyfilesExp.push_back (make_shared <Keyfile> (path));
					++keyfileCount;
				}

				if (keyfileCount == 0)
					throw KeyfilePathEmpty (SRC_POS, FilesystemPath (*keyfile));
			}
			else
			{
				keyfilesExp.push_back (keyfile);
			}
		}

		make_shared_auto (VolumePassword, newPassword);

		if (keyfilesExp.size() < 1)
		{
			newPassword->Set (*password);
		}
		else
		{
			SecureBuffer keyfilePool (password->Size() <= VolumePassword::MaxLegacySize? VolumePassword::MaxLegacySize: VolumePassword::MaxSize);

			// Pad password with zeros if shorter than max length
			keyfilePool.Zero();
			keyfilePool.CopyFrom (ConstBufferPtr (password->DataPtr(), password->Size()));

			// Apply all keyfiles
			foreach_ref (const Keyfile &k, keyfilesExp)
			{
				k.Apply (keyfilePool, emvSupportEnabled);
			}

			newPassword->Set (keyfilePool);
		}

		return newPassword;
	}

	shared_ptr <KeyfileList> Keyfile::DeserializeList (shared_ptr <Stream> stream, const string &name)
	{
		shared_ptr <KeyfileList> keyfiles;
		Serializer sr (stream);

		if (!sr.DeserializeBool (name + "Null"))
		{
			keyfiles.reset (new KeyfileList);
			foreach (const wstring &k, sr.DeserializeWStringList (name))
				keyfiles->push_back (make_shared <Keyfile> (k));
		}
		return keyfiles;
	}

	void Keyfile::SerializeList (shared_ptr <Stream> stream, const string &name, shared_ptr <KeyfileList> keyfiles)
	{
		Serializer sr (stream);
		sr.Serialize (name + "Null", keyfiles == nullptr);
		if (keyfiles)
		{
			list <wstring> sl;

			foreach_ref (const Keyfile &k, *keyfiles)
				sl.push_back (FilesystemPath (k));

			sr.Serialize (name, sl);
		}
	}

	bool Keyfile::HiddenFileWasPresentInKeyfilePath = false;
}