/*

* (C) 2018 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include "fuzzers.h"

#include <botan/numthry.h>

#include <botan/reducer.h>

void fuzz(const uint8_t in[], size_t len)

   {

   static const size_t max_bits = 2048;

   if(len <= 1 || len % 3 != 1)

      return;

   const size_t part_size = len / 3;

   if(part_size * 8 > max_bits)

      return;

   uint8_t flags = in[0];

   Botan::BigInt x = Botan::BigInt::decode(in + 1, part_size * 2);

   const Botan::BigInt p = Botan::BigInt::decode(in + 1 + part_size * 2, part_size);

   if(p.is_zero())

      return;

   if(flags & 1)

      x.flip_sign();

   const Botan::BigInt ref = x % p;

   const Botan::Modular_Reducer mod_p(p);

   const Botan::BigInt z = mod_p.reduce(x);

   if(ref != z)

      {

      FUZZER_WRITE_AND_CRASH("X = " << x << "\n"

                             << "P = " << p << "\n"

                             << "Z = " << z << "\n"

                             << "R = " << ref << "\n");

      }

   }