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/*************************************************
* Luby-Rackoff Source File *
* (C) 1999-2006 The Botan Project *
*************************************************/
#include <botan/lubyrack.h>
#include <botan/lookup.h>
#include <botan/bit_ops.h>
namespace Botan {
/*************************************************
* Luby-Rackoff Encryption *
*************************************************/
void LubyRackoff::enc(const byte in[], byte out[]) const
{
const u32bit OUTPUT_LENGTH = hash->OUTPUT_LENGTH;
SecureVector<byte> buffer(OUTPUT_LENGTH);
hash->update(K1);
hash->update(in, OUTPUT_LENGTH);
hash->final(buffer);
xor_buf(out + OUTPUT_LENGTH, in + OUTPUT_LENGTH, buffer, OUTPUT_LENGTH);
hash->update(K2);
hash->update(out + OUTPUT_LENGTH, OUTPUT_LENGTH);
hash->final(buffer);
xor_buf(out, in, buffer, OUTPUT_LENGTH);
hash->update(K1);
hash->update(out, OUTPUT_LENGTH);
hash->final(buffer);
xor_buf(out + OUTPUT_LENGTH, buffer, OUTPUT_LENGTH);
hash->update(K2);
hash->update(out + OUTPUT_LENGTH, OUTPUT_LENGTH);
hash->final(buffer);
xor_buf(out, buffer, OUTPUT_LENGTH);
}
/*************************************************
* Luby-Rackoff Decryption *
*************************************************/
void LubyRackoff::dec(const byte in[], byte out[]) const
{
const u32bit OUTPUT_LENGTH = hash->OUTPUT_LENGTH;
SecureVector<byte> buffer(OUTPUT_LENGTH);
hash->update(K2);
hash->update(in + OUTPUT_LENGTH, OUTPUT_LENGTH);
hash->final(buffer);
xor_buf(out, in, buffer, OUTPUT_LENGTH);
hash->update(K1);
hash->update(out, OUTPUT_LENGTH);
hash->final(buffer);
xor_buf(out + OUTPUT_LENGTH, in + OUTPUT_LENGTH, buffer, OUTPUT_LENGTH);
hash->update(K2);
hash->update(out + OUTPUT_LENGTH, OUTPUT_LENGTH);
hash->final(buffer);
xor_buf(out, buffer, OUTPUT_LENGTH);
hash->update(K1);
hash->update(out, OUTPUT_LENGTH);
hash->final(buffer);
xor_buf(out + OUTPUT_LENGTH, buffer, OUTPUT_LENGTH);
}
/*************************************************
* Luby-Rackoff Key Schedule *
*************************************************/
void LubyRackoff::key(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->name());
}
/*************************************************
* Return the name of this type *
*************************************************/
std::string LubyRackoff::name() const
{
return "Luby-Rackoff(" + hash->name() + ")";
}
/*************************************************
* Luby-Rackoff Constructor *
*************************************************/
LubyRackoff::LubyRackoff(const std::string& hash_name) :
BlockCipher(2*output_length_of(hash_name), 2, 32, 2),
hash(get_hash(hash_name))
{
}
}
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