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+/******
+ * 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 <botan/bigint.h>
+
+namespace Botan
+{
+
+class BOTAN_DLL GFpElement;
+/**
+* This class represents a GFpElement modulus including the modulus related
+* values necessary for the montgomery multiplication.
+*
+* Distributed under the terms of the Botan license
+*/
+class BOTAN_DLL 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
+