VeraCrypt

Documentation >> Security Requirements and Precautions >> Authenticity and Integrity

Authenticity and Integrity

VeraCrypt uses encryption to preserve the confidentiality of data it encrypts. VeraCrypt neither preserves nor verifies the integrity or authenticity of data it encrypts or decrypts. Hence, if you allow an adversary to modify data encrypted by VeraCrypt, he can set the value of any 16-byte block of the data to a random value or to a previous value, which he was able to obtain in the past. Note that the adversary cannot choose the value that you will obtain when VeraCrypt decrypts the modified block — the value will be random — unless the attacker restores an older version of the encrypted block, which he was able to obtain in the past. It is your responsibility to verify the integrity and authenticity of data encrypted or decrypted by VeraCrypt (for example, by using appropriate third-party software).

See also: Physical Security, Security Model

43c49a1afd32c'>src/Platform/StringConverter.cpp
blob: c6934aed3da765e7088d83bcc18bc6953c5e24a1 (plain)
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/*
 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) 2013-2016 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.
*/

#ifdef __GNUC__
#	include <cxxabi.h>
#endif
#include <locale>
#include <typeinfo>
#include "Buffer.h"
#include "Exception.h"
#include "ForEach.h"
#include "StringConverter.h"
#include "SystemException.h"

namespace VeraCrypt
{
	void StringConverter::Erase (string &str)
	{
		for (size_t i = 0; i < str.size(); ++i)
		{
			str[i] = ' ';
		}
	}

	void StringConverter::Erase (wstring &str)
	{
		for (size_t i = 0; i < str.size(); ++i)
		{
			str[i] = ' ';
		}
	}

	wstring StringConverter::FromNumber (double number)
	{
		wstringstream s;
		s << number;
		return s.str();
	}

	wstring StringConverter::FromNumber (int32 number)
	{
		wstringstream s;
		s << number;
		return s.str();
	}

	wstring StringConverter::FromNumber (uint32 number)
	{
		wstringstream s;
		s << number;
		return s.str();
	}

	wstring StringConverter::FromNumber (int64 number)
	{
		wstringstream s;
		s << number;
		return s.str();
	}

	wstring StringConverter::FromNumber (uint64 number)
	{
		wstringstream s;
		s << number;
		return s.str();
	}

	string StringConverter::GetTrailingNumber (const string &str)
	{
		size_t start = str.find_last_not_of ("0123456789");
		if (start == string::npos)
			return str;

		string s = str.substr (start + 1);
		if (s.empty ())
			throw ParameterIncorrect (SRC_POS);

		return s;
	}

	string StringConverter::GetTypeName (const type_info &typeInfo)
	{
		try
		{
#ifdef _MSC_VER
			// type_info::name() leaks memory as of MS VC++ 8.0
			string rawName (typeInfo.raw_name());

			size_t cut1 = (rawName.find (".?A") != string::npos) ? 4 : string::npos;
			size_t cut2 = rawName.find ("@");
			size_t cut3 = rawName.find ("@@");

			if (cut1 == string::npos || cut2 == string::npos || cut3 == string::npos)
				return typeInfo.name();

			return rawName.substr (cut2 + 1, cut3 - cut2 - 1) + "::" + rawName.substr (cut1, cut2 - cut1);

#elif defined (__GNUC__)
			int status;
			char *name = abi::__cxa_demangle (typeInfo.name(), nullptr, nullptr, &status);

			if (name)
			{
				string s (name);
				free (name);
				return s;
			}
#endif
		}
		catch (...) { }

		return typeInfo.name();
	}

	wstring StringConverter::QuoteSpaces (const wstring &str)
	{
		if (str.find (L' ') == string::npos)
			return str;

		wstring escaped (L"'");
		foreach (wchar_t c, str)
		{
			if (c == L'\'')
				escaped += L'\'';
			escaped += c;
		}
		return escaped + L'\'';
	}

	vector <string> StringConverter::Split (const string &str, const string &separators, bool returnEmptyFields)
	{
		vector <string> elements;

		if (!returnEmptyFields)
		{
			size_t p = 0;
			while ((p = str.find_first_not_of (separators, p)) != string::npos)
			{
				size_t end = str.find_first_of (separators, p);
				if (end == string::npos)
				{
					elements.push_back (str.substr (p));
					break;
				}

				elements.push_back (str.substr (p, end - p));
				p = end;
			}
		}
		else
		{
			string element;
			elements.push_back (element);
			foreach (char c, str)
			{
				if (separators.find (c) != string::npos)
				{
					element.erase();
					elements.push_back (element);
				}
				else
				{
					elements.back() += c;
				}
			}
		}

		return elements;
	}

	string StringConverter::StripTrailingNumber (const string &str)
	{
		size_t start = str.find_last_not_of ("0123456789");
		if (start == string::npos)
			return "";

		return str.substr (0, start + 1);
	}

	wstring StringConverter::ToExceptionString (const exception &ex)
	{
		const SystemException *sysEx = dynamic_cast <const SystemException *> (&ex);
		if (sysEx)
			return ToWide (sysEx->what()) + L": " + sysEx->SystemText() + L": " + sysEx->GetSubject();

		if (ex.what() && !string (ex.what()).empty())
			return ToWide (GetTypeName (typeid (ex)) + ": " + ex.what());

		return ToWide (GetTypeName (typeid (ex)));
	}

	string StringConverter::ToLower (const string &str)
	{
		string s;
		foreach (char c, str)
			s += tolower (c, locale());
		return s;
	}

	string StringConverter::ToSingle (const wstring &wstr, bool noThrow)
	{
		string str;
		ToSingle (wstr, str, noThrow);
		return str;
	}

	void StringConverter::ToSingle (const wstring &wstr, string &str, bool noThrow)
	{
		try
		{
			mbstate_t mbState;
			Memory::Zero (&mbState, sizeof (mbState));
			const wchar_t *src = wstr.c_str();

			size_t size = wcsrtombs (nullptr, &src, 0, &mbState);
			if (size == (size_t) -1)
				throw StringConversionFailed (SRC_POS, wstr);

			vector <char> buf (size + 1);
			Memory::Zero (&mbState, sizeof (mbState));

			if ((size = wcsrtombs (&buf[0], &src, buf.size(), &mbState)) == (size_t) -1)
				throw StringConversionFailed (SRC_POS, wstr);

			str.clear();
			str.insert (0, &buf.front(), size);
			Memory::Erase (&buf.front(), buf.size());
		}
		catch (...)
		{
			if (!noThrow)
				throw;
		}
	}

	uint32 StringConverter::ToUInt32 (const string &str)
	{
		uint32 n;
		stringstream ss (str);

		ss >> n;
		if (ss.fail() || n == 0xffffFFFFU)
			throw ParameterIncorrect (SRC_POS);

		return n;
	}

	uint32 StringConverter::ToUInt32 (const wstring &str)
	{
		uint32 n;
		wstringstream ss (str);

		ss >> n;
		if (ss.fail() || n == 0xffffFFFFU)
			throw ParameterIncorrect (SRC_POS);

		return n;
	}

	int32 StringConverter::ToInt32 (const string &str)
	{
		int32 n;
		stringstream ss (str);

		ss >> n;
		if (ss.fail() || n == 0x7fffFFFF || n == -0x7fffFFFF)
			throw ParameterIncorrect (SRC_POS);

		return n;
	}

	int32 StringConverter::ToInt32 (const wstring &str)
	{
		int32 n;
		wstringstream ss (str);

		ss >> n;
		if (ss.fail() || n == 0x7fffFFFF || n == -0x7fffFFFF)
			throw ParameterIncorrect (SRC_POS);

		return n;
	}

	uint64 StringConverter::ToUInt64 (const string &str)
	{
		uint64 n;
		stringstream ss (str);

		ss >> n;
		if (ss.fail() || n == 0xffffFFFFffffFFFFULL)
			throw ParameterIncorrect (SRC_POS);

		return n;
	}

	uint64 StringConverter::ToUInt64 (const wstring &str)
	{
		uint64 n;
		wstringstream ss (str);

		ss >> n;
		if (ss.fail() || n == 0xffffFFFFffffFFFFULL)
			throw ParameterIncorrect (SRC_POS);

		return n;
	}

	int64 StringConverter::ToInt64 (const string &str)
	{
		int64 n;
		stringstream ss (str);

		ss >> n;
		if (ss.fail() || n == 0x7fffFFFFffffFFFFLL || n == -0x7fffFFFFffffFFFFLL)
			throw ParameterIncorrect (SRC_POS);

		return n;
	}

	int64 StringConverter::ToInt64 (const wstring &str)
	{
		int64 n;
		wstringstream ss (str);

		ss >> n;
		if (ss.fail() || n == 0x7fffFFFFffffFFFFLL || n == -0x7fffFFFFffffFFFFLL)
			throw ParameterIncorrect (SRC_POS);

		return n;
	}

	string StringConverter::ToUpper (const string &str)
	{
		string s;
		foreach (char c, str)
			s += toupper (c, locale());
		return s;
	}

	wstring StringConverter::ToWide (const string &str, bool noThrow)
	{
		try
		{
			mbstate_t mbState;
			Memory::Zero (&mbState, sizeof (mbState));
			const char *src = str.c_str();

			size_t size = mbsrtowcs (nullptr, &src, 0, &mbState);
			if (size == (size_t) -1)
				throw StringConversionFailed (SRC_POS);

			vector <wchar_t> buf (size + 1);
			Memory::Zero (&mbState, sizeof (mbState));

			if ((size = mbsrtowcs (&buf[0], &src, buf.size(), &mbState)) == (size_t) -1)
				throw StringConversionFailed (SRC_POS);

			wstring s;
			s.insert (s.begin(), buf.begin(), buf.begin() + size);
			return s;
		}
		catch (...)
		{
			if (noThrow)
				return L"";
			throw;
		}
	}

	void StringConverter::ToWideBuffer (const wstring &str, wchar_t *buffer, size_t bufferSize)
	{
		if (str.length() < 1)
		{
			buffer[0] = 0;
			return;
		}

		BufferPtr (
			(byte *) buffer,
			bufferSize).CopyFrom (
				ConstBufferPtr ((byte *) (wstring (str).c_str()),
				(str.length() + 1) * sizeof (wchar_t)
			)
		);
	}

	string StringConverter::Trim (const string &str)
	{
		size_t start = 0;
		size_t end = str.size();
		if (end < 1)
			return str;

		foreach (char c, str)
		{
			if (c > ' ')
				break;
			++start;
		}

		foreach_reverse (char c, str)
		{
			if (c > ' ')
				break;
			--end;
		}

		return str.substr (start, end - start);
	}
}