/****************************************************** * Modulus and related data for a specific * * implementation of GF(p) (header file) * * * * (C) 2008 Martin Döring * * doering@cdc.informatik.tu-darmstadt.de * * Christoph Ludwig * * ludwig@fh-worms.de * * Falko Strenzke * * strenzke@flexsecure.de * ******************************************************/ #ifndef BOTAN_GFP_MODULUS_H__ #define BOTAN_GFP_MODULUS_H__ #include namespace Botan { class GFpElement; /** * This class represents a GFpElement modulus including the modulus related * values necessary for the montgomery multiplication. */ class GFpModulus { friend class GFpElement; private: BigInt m_p; // the modulus itself mutable BigInt m_p_dash; mutable BigInt m_r; mutable BigInt m_r_inv; public: /** * Construct a GF(P)-Modulus from a BigInt */ GFpModulus(BigInt p) : m_p(p), m_p_dash(), m_r(), m_r_inv() {} /** * Tells whether the precomputations necessary for the use of the * montgomery multiplication have yet been established. * @result true if the precomputated value are already available. */ inline bool has_precomputations() const { return(!m_p_dash.is_zero() && !m_r.is_zero() && !m_r_inv.is_zero()); } /** * Swaps this with another GFpModulus, does not throw. * @param other the GFpModulus to swap *this with. */ inline void swap(GFpModulus& other) { m_p.swap(other.m_p); m_p_dash.swap(other.m_p_dash); m_r.swap(other.m_r); m_r_inv.swap(other.m_r_inv); } /** * Tells whether the modulus of *this is equal to the argument. * @param mod the modulus to compare this with * @result true if the modulus of *this and the argument are equal. */ inline bool p_equal_to(const BigInt& mod) const { return (m_p == mod); } /** * Return the modulus of this GFpModulus. * @result the modulus of *this. */ inline const BigInt get_p() const { return m_p; } /** * returns the montgomery multiplication related value r. * Warning: will be zero if precomputations have not yet been * performed! * @result r */ inline const BigInt get_r() const { return m_r; } /** * returns the montgomery multiplication related value r^{-1}. * Warning: will be zero if precomputations have not yet been * performed! * @result r^{-1} */ inline const BigInt get_r_inv() const { return m_r_inv; } /** * returns the montgomery multiplication related value p'. * Warning: will be zero if precomputations have not yet been * performed! * @result p' */ inline const BigInt get_p_dash() const { return m_p_dash; } // default cp-ctor, op= are fine }; } #endif