1 files changed, 49 insertions, 0 deletions
diff --git a/src/lib/pubkey/blinding.cpp b/src/lib/pubkey/blinding.cpp
new file mode 100644
index 000000000..c4c0e3b6e
--- /dev/null
+++ b/src/lib/pubkey/blinding.cpp
@@ -0,0 +1,49 @@
+/*
+* Blinding for public key operations
+* (C) 1999-2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/blinding.h>
+#include <botan/numthry.h>
+
+namespace Botan {
+
+/*
+* Blinder Constructor
+*/
+Blinder::Blinder(const BigInt& e, const BigInt& d, const BigInt& n)
+   {
+   if(e < 1 || d < 1 || n < 1)
+      throw Invalid_Argument("Blinder: Arguments too small");
+
+   reducer = Modular_Reducer(n);
+   this->e = e;
+   this->d = d;
+   }
+
+/*
+* Blind a number
+*/
+BigInt Blinder::blind(const BigInt& i) const
+   {
+   if(!reducer.initialized())
+      return i;
+
+   e = reducer.square(e);
+   d = reducer.square(d);
+   return reducer.multiply(i, e);
+   }
+
+/*
+* Unblind a number
+*/
+BigInt Blinder::unblind(const BigInt& i) const
+   {
+   if(!reducer.initialized())
+      return i;
+   return reducer.multiply(i, d);
+   }
+
+}