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Diffstat (limited to '')
-rw-r--r-- | CryptoPP/gf256.cpp | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/CryptoPP/gf256.cpp b/CryptoPP/gf256.cpp new file mode 100644 index 000000000..72026d1e1 --- /dev/null +++ b/CryptoPP/gf256.cpp @@ -0,0 +1,34 @@ +// 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 |