lubyrack.cpp

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/*
* Luby-Rackoff
* (C) 1999-2008 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
 
#include <botan/lubyrack.h>
#include <botan/internal/xor_buf.h>
 
namespace Botan {
 
/*
* Luby-Rackoff Encryption
*/
void LubyRackoff::encrypt_n(const byte in[], byte out[], size_t blocks) const
   {
   const size_t len = hash->output_length();
 
   SecureVector<byte> buffer_vec(len);
   byte* buffer = &buffer_vec[0];
 
   for(size_t i = 0; i != blocks; ++i)
      {
      hash->update(K1);
      hash->update(in, len);
      hash->final(buffer);
      xor_buf(out + len, in + len, buffer, len);
 
      hash->update(K2);
      hash->update(out + len, len);
      hash->final(buffer);
      xor_buf(out, in, buffer, len);
 
      hash->update(K1);
      hash->update(out, len);
      hash->final(buffer);
      xor_buf(out + len, buffer, len);
 
      hash->update(K2);
      hash->update(out + len, len);
      hash->final(buffer);
      xor_buf(out, buffer, len);
 
      in += 2 * len;
      out += 2 * len;
      }
   }
 
/*
* Luby-Rackoff Decryption
*/
void LubyRackoff::decrypt_n(const byte in[], byte out[], size_t blocks) const
   {
   const size_t len = hash->output_length();
 
   SecureVector<byte> buffer_vec(len);
   byte* buffer = &buffer_vec[0];
 
   for(size_t i = 0; i != blocks; ++i)
      {
      hash->update(K2);
      hash->update(in + len, len);
      hash->final(buffer);
      xor_buf(out, in, buffer, len);
 
      hash->update(K1);
      hash->update(out, len);
      hash->final(buffer);
      xor_buf(out + len, in + len, buffer, len);
 
      hash->update(K2);
      hash->update(out + len, len);
      hash->final(buffer);
      xor_buf(out, buffer, len);
 
      hash->update(K1);
      hash->update(out, len);
      hash->final(buffer);
      xor_buf(out + len, buffer, len);
 
      in += 2 * len;
      out += 2 * len;
      }
   }
 
/*
* Luby-Rackoff Key Schedule
*/
void LubyRackoff::key_schedule(const byte key[], size_t length)
   {
   K1.resize(length / 2);
   K2.resize(length / 2);
   copy_mem(&K1[0], key             , length / 2);
   copy_mem(&K2[0], key + length / 2, length / 2);
   }
 
/*
* Clear memory of sensitive data
*/
void LubyRackoff::clear()
   {
   zeroise(K1);
   zeroise(K2);
   hash->clear();
   }
 
/*
* Return a clone of this object
*/
BlockCipher* LubyRackoff::clone() const
   {
   return new LubyRackoff(hash->clone());
   }
 
/*
* Return the name of this type
*/
std::string LubyRackoff::name() const
   {
   return "Luby-Rackoff(" + hash->name() + ")";
   }
 
/*
* Luby-Rackoff Constructor
*/
LubyRackoff::LubyRackoff(HashFunction* h) : hash(h)
   {
   }
 
}