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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/xor_buf.h>
namespace Botan {
/*
* Luby-Rackoff Encryption
*/
void LubyRackoff::enc(const byte in[], byte out[]) const
{
const u32bit len = hash->OUTPUT_LENGTH;
SecureVector<byte> buffer(len);
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);
}
/*
* Luby-Rackoff Decryption
*/
void LubyRackoff::dec(const byte in[], byte out[]) const
{
const u32bit len = hash->OUTPUT_LENGTH;
SecureVector<byte> buffer(len);
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);
}
/*
* Luby-Rackoff Key Schedule
*/
void LubyRackoff::key_schedule(const byte key[], u32bit length)
{
K1.set(key, length / 2);
K2.set(key + length / 2, length / 2);
}
/*
* Clear memory of sensitive data
*/
void LubyRackoff::clear() throw()
{
K1.clear();
K2.clear();
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) :
BlockCipher(2 * (h ? h->OUTPUT_LENGTH: 0),
2, 32, 2),
hash(h)
{
}
}
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