constants.h

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// MIT License
//
// Copyright (c) 2019 Oleksandr Tkachenko
// Cryptography and Privacy Engineering Group (ENCRYPTO)
// TU Darmstadt, Germany
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
 
#pragma once
 
#include <iostream>
#include <limits>
#include <string>
 
#include "config.h"
#include "typedefs.h"
 
namespace encrypto::motion {
 
// just in case if we all of a sudden will decide to change the name
constexpr std::string_view kFrameworkName{"MOTION"};
 
// abbreviation for megabytes
constexpr std::size_t kMb{1024 * 1024};
 
// Verbose debug flag. If kDebug equals false, this flag will always be interpreted as false.
// Verbose means here that MOTION will log virtually everything: not only the performed actions but
// also the sent and received messages. One may need this, e.g., for debugging correctness of the
// protocols to better understand what went wrong. This may be _very_ slow and need a lot of storage
// for logs! So try to keep the code small if you need this flag for debugging.
constexpr bool kVerboseDebugWish{false};
 
// Don't compile unnecessary code if verbose debugging is not needed
constexpr bool kVerboseDebug{kDebug && kVerboseDebugWish};
 
constexpr std::size_t kAesKeySize{16};
 
constexpr std::size_t kAesBlockSize{16};
 
constexpr std::size_t kAesIvSize{kAesBlockSize / 2};
 
constexpr std::size_t kMessageSizeBytelen{sizeof(std::uint32_t)};
 
// the maximum allowed message size in flatbuffers
// 2^31, approx. 2 GB
constexpr std::uint32_t kMaxMessageSize{std::numeric_limits<std::uint32_t>::max() / 2};
 
// symmetric security parameter
constexpr std::size_t kKappa{128};
 
// stack size for fibers
// Increase the fiber stack size when in debug mode because it requires storing additional debugging
// information, which, however, would be an unnecessary memory overhead when built in release mode,
// thus increase the fiber stack size only in debug mode
constexpr std::size_t kFiberStackSize = kDebug ? 32 * 1024 : 14 * 1024;
 
enum class FiberStackAllocator {
  // standard allocator
  kFixedSize,
  // allocate the stacks from a memory pool
  kPooledFixedSize,
  // use an allocator for fiber stacks that inserts a guard page at the end of
  // the stack space resulting in a SIGSEGV if a stack overflow happens
  kProtectedFixedSize,
};
 
// standard allocator for fiber stacks
constexpr FiberStackAllocator kFiberStackAllocator{FiberStackAllocator::kFixedSize};
 
}  // namespace encrypto::motion