1 files changed, 53 insertions, 0 deletions
diff --git a/lib/engine/gnump/gmp_powm.cpp b/lib/engine/gnump/gmp_powm.cpp
new file mode 100644
index 000000000..70c2b2f5e
--- /dev/null
+++ b/lib/engine/gnump/gmp_powm.cpp
@@ -0,0 +1,53 @@
+/*
+* GMP Modular Exponentiation
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/internal/gnump_engine.h>
+#include <botan/internal/gmp_wrap.h>
+
+namespace Botan {
+
+namespace {
+
+/*
+* GMP Modular Exponentiator
+*/
+class GMP_Modular_Exponentiator : public Modular_Exponentiator
+   {
+   public:
+      void set_base(const BigInt& b) { base = b; }
+      void set_exponent(const BigInt& e) { exp = e; }
+      BigInt execute() const;
+      Modular_Exponentiator* copy() const
+         { return new GMP_Modular_Exponentiator(*this); }
+
+      GMP_Modular_Exponentiator(const BigInt& n) : mod(n) {}
+   private:
+      GMP_MPZ base, exp, mod;
+   };
+
+/*
+* Compute the result
+*/
+BigInt GMP_Modular_Exponentiator::execute() const
+   {
+   GMP_MPZ r;
+   mpz_powm(r.value, base.value, exp.value, mod.value);
+   return r.to_bigint();
+   }
+
+}
+
+/*
+* Return the GMP-based modular exponentiator
+*/
+Modular_Exponentiator* GMP_Engine::mod_exp(const BigInt& n,
+                                           Power_Mod::Usage_Hints) const
+   {
+   return new GMP_Modular_Exponentiator(n);
+   }
+
+}