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// gf256.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#include "gf256.h"
NAMESPACE_BEGIN(CryptoPP)
GF256::Element GF256::Multiply(Element a, Element b) const
{
word result = 0, t = b;
for (unsigned int i=0; i<8; i++)
{
result <<= 1;
if (result & 0x100)
result ^= m_modulus;
t <<= 1;
if (t & 0x100)
result ^= a;
}
return (GF256::Element) result;
}
GF256::Element GF256::MultiplicativeInverse(Element a) const
{
Element result = a;
for (int i=1; i<7; i++)
result = Multiply(Square(result), a);
return Square(result);
}
NAMESPACE_END
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