Crypto++  5.6.5
Free C++ class library of cryptographic schemes
gf256.h
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1 // gf256.h - written and placed in the public domain by Wei Dai
2 
3 //! \file gf256.h
4 //! \brief Classes and functions for schemes over GF(256)
5 
6 #ifndef CRYPTOPP_GF256_H
7 #define CRYPTOPP_GF256_H
8 
9 #include "cryptlib.h"
10 #include "misc.h"
11 
12 NAMESPACE_BEGIN(CryptoPP)
13 
14 //! \brief GF(256) with polynomial basis
15 class GF256
16 {
17 public:
18  typedef byte Element;
19  typedef int RandomizationParameter;
20 
21  GF256(byte modulus) : m_modulus(modulus) {}
22 
23  Element RandomElement(RandomNumberGenerator &rng, int ignored = 0) const
24  {CRYPTOPP_UNUSED(ignored); return rng.GenerateByte();}
25 
26  bool Equal(Element a, Element b) const
27  {return a==b;}
28 
29  Element Zero() const
30  {return 0;}
31 
32  Element Add(Element a, Element b) const
33  {return a^b;}
34 
35  Element& Accumulate(Element &a, Element b) const
36  {return a^=b;}
37 
38  Element Inverse(Element a) const
39  {return a;}
40 
41  Element Subtract(Element a, Element b) const
42  {return a^b;}
43 
44  Element& Reduce(Element &a, Element b) const
45  {return a^=b;}
46 
47  Element Double(Element a) const
48  {CRYPTOPP_UNUSED(a); return 0;}
49 
50  Element One() const
51  {return 1;}
52 
53  Element Multiply(Element a, Element b) const;
54 
55  Element Square(Element a) const
56  {return Multiply(a, a);}
57 
58  bool IsUnit(Element a) const
59  {return a != 0;}
60 
61  Element MultiplicativeInverse(Element a) const;
62 
63  Element Divide(Element a, Element b) const
64  {return Multiply(a, MultiplicativeInverse(b));}
65 
66 private:
67  word m_modulus;
68 };
69 
70 NAMESPACE_END
71 
72 #endif
Utility functions for the Crypto++ library.
Abstract base classes that provide a uniform interface to this library.
Square block cipher.
Definition: square.h:24
Interface for random number generators.
Definition: cryptlib.h:1188
GF(256) with polynomial basis.
Definition: gf256.h:15
virtual byte GenerateByte()
Generate new random byte and return it.
Definition: cryptlib.cpp:291
Crypto++ library namespace.