[libcalamares] Add printable-entropy (e.g. for password salt)
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@ -26,7 +26,7 @@ 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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if ( size < 1)
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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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@ -55,7 +55,6 @@ CalamaresUtils::getEntropy( int size, QByteArray& b )
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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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@ -78,3 +77,48 @@ CalamaresUtils::getEntropy( int size, QByteArray& b )
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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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@ -40,6 +40,14 @@ enum class EntropySource
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* bytes from a suitable source. Returns which source was used.
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*/
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DLLEXPORT EntropySource getEntropy( int size, QByteArray& b );
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/** @brief Fill string @p s with exactly @p size random printable ASCII characters
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*
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* The characters are picked from a set of 64 (2^6). The string
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* contains 6 * size bits of entropy. * Returns which source was used.
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* @see getEntropy
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*/
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DLLEXPORT EntropySource getPrintableEntropy( int size, QString& s );
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} // namespace CalamaresUtils
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#endif
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@ -185,18 +185,37 @@ LibCalamaresTests::testEntropy()
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auto r0 = CalamaresUtils::getEntropy( 0, data );
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QCOMPARE( CalamaresUtils::EntropySource::None, r0 );
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QCOMPARE( 0, data.size() );
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QCOMPARE( data.size(), 0 );
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auto r1 = CalamaresUtils::getEntropy( 16, data );
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QVERIFY( r1 != CalamaresUtils::EntropySource::None );
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QCOMPARE( 16, data.size() );
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QCOMPARE( data.size(), 16 );
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// This can randomly fail (but not often)
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QVERIFY( data.at( data.size() - 1 ) != char( 0xcb ) );
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auto r2 = CalamaresUtils::getEntropy( 8, data );
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QVERIFY( r2 != CalamaresUtils::EntropySource::None );
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QCOMPARE( 8, data.size() );
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QCOMPARE( data.size(), 8 );
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QCOMPARE( r1, r2 );
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// This can randomly fail (but not often)
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QVERIFY( data.at( data.size() - 1 ) != char( 0xcb ) );
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}
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void
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LibCalamaresTests::testPrintableEntropy()
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{
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QString s;
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auto r0 = CalamaresUtils::getPrintableEntropy( 0, s );
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QCOMPARE( CalamaresUtils::EntropySource::None, r0 );
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QCOMPARE( s.length(), 0 );
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auto r1 = CalamaresUtils::getPrintableEntropy( 16, s );
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QVERIFY( r1 != CalamaresUtils::EntropySource::None );
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QCOMPARE( s.length(), 16 );
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for ( QChar c : s )
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{
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QVERIFY( c.isPrint() );
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QCOMPARE( c.cell(), 0 );
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}
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}
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@ -42,6 +42,7 @@ private Q_SLOTS:
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/** @brief Tests the entropy functions. */
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void testEntropy();
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void testPrintableEntropy();
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};
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#endif
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