76 lines
2.0 KiB
C++
76 lines
2.0 KiB
C++
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/* === This file is part of Calamares - <https://github.com/calamares> ===
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*
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* Copyright 2019-2020, Adriaan de Groot <groot@kde.org>
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*
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* Calamares is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Calamares is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Calamares. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "Entropy.h"
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#include <QFile>
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#include <random>
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CalamaresUtils::EntropySource
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CalamaresUtils::getEntropy( int size, QByteArray& b )
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{
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b.clear();
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b.resize( size );
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char* buffer = b.data();
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std::fill( buffer, buffer + size, 0xcb );
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int readSize = 0;
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QFile urandom( "/dev/urandom" );
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if ( urandom.exists() && urandom.open( QIODevice::ReadOnly ) )
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{
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readSize = urandom.read( buffer, size );
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urandom.close();
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}
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if ( readSize >= size )
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{
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return EntropySource::URandom;
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}
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// If it wasn't available, or did not return enough bytes,
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// complete it with twister (and tell the client).
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std::random_device r;
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std::seed_seq seed { r(), r(), r(), r(), r(), r(), r(), r() };
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std::mt19937_64 twister( seed );
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std::uint64_t next = 0;
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do
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{
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next = twister();
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// Eight times, for a 64-bit next
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#define GET_ONE_BYTE \
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if ( readSize < size ) \
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{ \
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buffer[ readSize++ ] = next & 0xff; \
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next = next >> 8; \
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}
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GET_ONE_BYTE
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GET_ONE_BYTE
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GET_ONE_BYTE
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GET_ONE_BYTE
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GET_ONE_BYTE
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GET_ONE_BYTE
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GET_ONE_BYTE
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GET_ONE_BYTE
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} while ( readSize < size );
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return EntropySource::Twister;
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}
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