120 lines
3.0 KiB
C++
120 lines
3.0 KiB
C++
/* === This file is part of Calamares - <https://calamares.io> ===
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*
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* SPDX-FileCopyrightText: 2019-2020 Adriaan de Groot <groot@kde.org>
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* SPDX-License-Identifier: GPL-3.0-or-later
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*
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*
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* Calamares is Free Software: see the License-Identifier above.
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*
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*
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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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constexpr const char filler = char( 0xcb );
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b.fill( filler );
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b.clear();
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if ( size < 1 )
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{
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return EntropySource::None;
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}
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b.fill( filler, size );
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char* buffer = b.data();
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qint64 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++ ] = char( next & 0xffU ); \
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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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CalamaresUtils::EntropySource
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CalamaresUtils::getPrintableEntropy( int size, QString& s )
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{
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s.clear();
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if ( size < 1 )
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{
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return EntropySource::None;
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}
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static const char salt_chars[] = { '.', '/', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D',
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'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
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'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
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'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };
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static_assert( sizeof( salt_chars ) == 64, "Missing salt_chars" );
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// Number of bytes we're going to need
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int byteSize = ( ( size * 6 ) / 8 ) + 1;
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QByteArray b;
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EntropySource r = getEntropy( byteSize, b );
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int bitsLeft = 0;
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int byteOffset = 0;
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qint64 next = 0;
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do
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{
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if ( bitsLeft < 6 )
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{
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next = ( next << 8 ) | b.at( byteOffset++ );
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bitsLeft += 8;
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}
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char c = salt_chars[ next & 0b0111111 ];
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next >>= 6;
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bitsLeft -= 6;
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s.append( c );
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} while ( ( s.length() < size ) && ( byteOffset < b.size() ) );
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if ( s.length() < size )
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{
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// It's incomplete, not really no-entropy
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return EntropySource::None;
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}
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return r;
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}
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