/* 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. */ #ifndef TC_WINDOWS #include <sys/types.h> #include <errno.h> #include <fcntl.h> #endif #include "RandomNumberGenerator.h" #include "Volume/Crc32.h" namespace VeraCrypt { void RandomNumberGenerator::AddSystemDataToPool (bool fast) { SecureBuffer buffer (PoolSize); #ifdef TC_WINDOWS #ifndef DEBUG throw NotImplemented (SRC_POS); #endif #else int urandom = open ("/dev/urandom", O_RDONLY); throw_sys_sub_if (urandom == -1, L"/dev/urandom"); finally_do_arg (int, urandom, { close (finally_arg); }); throw_sys_sub_if (read (urandom, buffer, buffer.Size()) == -1, L"/dev/urandom"); AddToPool (buffer); if (!fast) { // Read all bytes available in /dev/random up to buffer size int random = open ("/dev/random", O_RDONLY | O_NONBLOCK); throw_sys_sub_if (random == -1, L"/dev/random"); finally_do_arg (int, random, { close (finally_arg); }); throw_sys_sub_if (read (random, buffer, buffer.Size()) == -1 && errno != EAGAIN, L"/dev/random"); AddToPool (buffer); } #endif } void RandomNumberGenerator::AddToPool (const ConstBufferPtr &data) { if (!Running) throw NotInitialized (SRC_POS); ScopeLock lock (AccessMutex); for (size_t i = 0; i < data.Size(); ++i) { Pool[WriteOffset++] += data[i]; if (WriteOffset >= PoolSize) WriteOffset = 0; if (++BytesAddedSincePoolHashMix >= MaxBytesAddedBeforePoolHashMix) HashMixPool(); } } void RandomNumberGenerator::GetData (const BufferPtr &buffer, bool fast, bool allowAnyLength) { if (!Running) throw NotInitialized (SRC_POS); if (!allowAnyLength && (buffer.Size() > PoolSize)) throw ParameterIncorrect (SRC_POS); ScopeLock lock (AccessMutex); size_t bufferLen = buffer.Size(), loopLen; byte* pbBuffer = buffer.Get(); // Poll system for data AddSystemDataToPool (fast); HashMixPool(); while (bufferLen > 0) { if (bufferLen > PoolSize) { loopLen = PoolSize; bufferLen -= PoolSize; } else { loopLen = bufferLen; bufferLen = 0; } // Transfer bytes from pool to output buffer for (size_t i = 0; i < loopLen; ++i) { pbBuffer[i] += Pool[ReadOffset++]; if (ReadOffset >= PoolSize) ReadOffset = 0; } // Invert and mix the pool for (size_t i = 0; i < Pool.Size(); ++i) { Pool[i] = ~Pool[i]; } AddSystemDataToPool (true); HashMixPool(); // XOR the current pool content into the output buffer to prevent pool state leaks for (size_t i = 0; i < loopLen; ++i) { pbBuffer[i] ^= Pool[ReadOffset++]; if (ReadOffset >= PoolSize) ReadOffset = 0; } pbBuffer += loopLen; } } shared_ptr <Hash> RandomNumberGenerator::GetHash () { ScopeLock lock (AccessMutex); return PoolHash; } void RandomNumberGenerator::HashMixPool () { BytesAddedSincePoolHashMix = 0; for (size_t poolPos = 0; poolPos < Pool.Size(); ) { // Compute the message digest of the entire pool using the selected hash function SecureBuffer digest (PoolHash->GetDigestSize()); PoolHash->ProcessData (Pool); PoolHash->GetDigest (digest); // Add the message digest to the pool for (size_t digestPos = 0; digestPos < digest.Size() && poolPos < Pool.Size(); ++digestPos) { Pool[poolPos++] += digest[digestPos]; } } } void RandomNumberGenerator::SetHash (shared_ptr <Hash> hash) { ScopeLock lock (AccessMutex); PoolHash = hash; } void RandomNumberGenerator::Start () { ScopeLock lock (AccessMutex); if (IsRunning()) return; BytesAddedSincePoolHashMix = 0; ReadOffset = 0; WriteOffset = 0; Running = true; EnrichedByUser = false; Pool.Allocate (PoolSize, 16); Test(); if (!PoolHash) { // First hash algorithm is the default one PoolHash = Hash::GetAvailableAlgorithms().front(); } AddSystemDataToPool (true); } void RandomNumberGenerator::Stop () { ScopeLock lock (AccessMutex); if (Pool.IsAllocated()) Pool.Free (); PoolHash.reset(); EnrichedByUser = false; Running = false; } void RandomNumberGenerator::Test () { shared_ptr <Hash> origPoolHash = PoolHash; PoolHash.reset (new Ripemd160()); Pool.Zero(); Buffer buffer (1); for (size_t i = 0; i < PoolSize * 10; ++i) { buffer[0] = (byte) i; AddToPool (buffer); } if (Crc32::ProcessBuffer (Pool) != 0x2de46d17) throw TestFailed (SRC_POS); buffer.Allocate (PoolSize); buffer.CopyFrom (PeekPool()); AddToPool (buffer); if (Crc32::ProcessBuffer (Pool) != 0xcb88e019) throw TestFailed (SRC_POS); PoolHash = origPoolHash; } Mutex RandomNumberGenerator::AccessMutex; size_t RandomNumberGenerator::BytesAddedSincePoolHashMix; bool RandomNumberGenerator::EnrichedByUser; SecureBuffer RandomNumberGenerator::Pool; shared_ptr <Hash> RandomNumberGenerator::PoolHash; size_t RandomNumberGenerator::ReadOffset; bool RandomNumberGenerator::Running = false; size_t RandomNumberGenerator::WriteOffset; }