blinding.cpp

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/*
* 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);
   }
 
}