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diff --git a/lib/math/numbertheory/reducer.h b/lib/math/numbertheory/reducer.h
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+/*
+* Modular Reducer
+* (C) 1999-2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_MODULAR_REDUCER_H__
+#define BOTAN_MODULAR_REDUCER_H__
+
+#include <botan/numthry.h>
+
+namespace Botan {
+
+/**
+* Modular Reducer (using Barrett's technique)
+*/
+class BOTAN_DLL Modular_Reducer
+   {
+   public:
+      const BigInt& get_modulus() const { return modulus; }
+
+      BigInt reduce(const BigInt& x) const;
+
+      /**
+      * Multiply mod p
+      * @param x
+      * @param y
+      * @return (x * y) % p
+      */
+      BigInt multiply(const BigInt& x, const BigInt& y) const
+         { return reduce(x * y); }
+
+      /**
+      * Square mod p
+      * @param x
+      * @return (x * x) % p
+      */
+      BigInt square(const BigInt& x) const
+         { return reduce(Botan::square(x)); }
+
+      /**
+      * Cube mod p
+      * @param x
+      * @return (x * x * x) % p
+      */
+      BigInt cube(const BigInt& x) const
+         { return multiply(x, this->square(x)); }
+
+      bool initialized() const { return (mod_words != 0); }
+
+      Modular_Reducer() { mod_words = 0; }
+      Modular_Reducer(const BigInt& mod);
+   private:
+      BigInt modulus, modulus_2, mu;
+      size_t mod_words;
+   };
+
+}
+
+#endif