symkey.cpp

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/*************************************************
* SymmetricKey Source File                       *
* (C) 1999-2002 The Botan Project                *
*************************************************/

#include <botan/symkey.h>
#include <botan/hex.h>
#include <botan/rng.h>

namespace Botan {

/*************************************************
* Create a SymmetricKey from a byte string       *
*************************************************/
void SymmetricKey::change(const byte in[], u32bit n)
   {
   key.create(n);
   key.copy(in, n);
   }

/*************************************************
* Create a SymmetricKey from RNG output          *
*************************************************/
void SymmetricKey::change(u32bit length)
   {
   key.create(length);
   Global_RNG::randomize(key, length);
   }

/*************************************************
* Create a SymmeticKey from a hex string         *
*************************************************/
void SymmetricKey::change(const std::string& hex_string)
   {
   SecureVector<byte> hex;
   for(u32bit j = 0; j != hex_string.length(); j++)
      if(Hex_Decoder::is_valid(hex_string[j]))
         hex.append(hex_string[j]);

   if(hex.size() % 2 != 0)
      throw Invalid_Argument("SymmeticKey: hex string must encode full bytes");
   key.create(hex.size() / 2);
   for(u32bit j = 0; j != key.size(); j++)
      key[j] = Hex_Decoder::decode(hex.ptr() + 2*j);
   }

/*************************************************
* XOR Operation for SymmetricKeys                *
*************************************************/
SymmetricKey& SymmetricKey::operator^=(const SymmetricKey& k)
   {
   if(&k == this) { key.clear(); return (*this); }
   xor_buf(key.ptr(), k, std::min(length(), k.length()));
   return (*this);
   }

/*************************************************
* XOR Operation for SymmetricKeys                *
*************************************************/
SymmetricKey operator^(const SymmetricKey& k1, const SymmetricKey& k2)
   {
   SecureVector<byte> ret(std::max(k1.length(), k2.length()));
   ret.copy(k1, k1.length());
   xor_buf(ret, k2, k2.length());
   return SymmetricKey(ret);
   }

}