Move GF(p) math code from pk/ecdsa to math/gfpmath

1 files changed, 124 insertions, 0 deletions

diff --git a/src/math/gfpmath/gfp_modulus.h b/src/math/gfpmath/gfp_modulus.h
new file mode 100644
index 000000000..5edf44ba0
--- /dev/null
+++ b/src/math/gfpmath/gfp_modulus.h
@@ -0,0 +1,124 @@
+/******************************************************
+ * Modulus and related data for a specific            *
+ * implementation of  GF(p) (header file)             *
+ *                                                    *
+ * (C) 2008 Martin Döring                             *
+ *          [email protected]    *
+ *          Christoph Ludwig                          *
+ *          [email protected]                        *
+ *          Falko Strenzke                            *
+ *          [email protected]                    *
+ ******************************************************/
+
+#ifndef BOTAN_MATH_GF_GFP_MODULUS_H_GUARD_
+#define BOTAN_MATH_GF_GFP_MODULUS_H_GUARD_
+
+#include <botan/bigint.h>
+
+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