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-rw-r--r--CryptoPP/gf256.cpp34
1 files changed, 34 insertions, 0 deletions
diff --git a/CryptoPP/gf256.cpp b/CryptoPP/gf256.cpp
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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