C++ (Cpp) bigint_monty_mul Examples

Example #1

File: monty_exp.cpp Project: noloader/botan

Montgomery_Exponentation_State::Montgomery_Exponentation_State(const BigInt& g,
                                                               const BigInt& p,
                                                               const Modular_Reducer& mod_p,
                                                               size_t window_bits) :
   m_p(p),
   m_p_words(p.sig_words()),
   m_window_bits(window_bits)
   {
   if(p.is_positive() == false || p.is_even())
      throw Invalid_Argument("Cannot use Montgomery reduction on even or negative integer");

   if(window_bits > 12) // really even 8 is too large ...
      throw Invalid_Argument("Montgomery window bits too large");

   m_mod_prime = monty_inverse(m_p.word_at(0));

   const BigInt r = BigInt::power_of_2(m_p_words * BOTAN_MP_WORD_BITS);
   m_R_mod = mod_p.reduce(r);
   m_R2_mod = mod_p.square(m_R_mod);

   m_g.resize(1U << m_window_bits);

   BigInt z(BigInt::Positive, 2 * (m_p_words + 1));
   secure_vector<word> workspace(z.size());

   m_g[0] = 1;

   bigint_monty_mul(z, m_g[0], m_R2_mod,
                    m_p.data(), m_p_words, m_mod_prime,
                    workspace.data());
   m_g[0] = z;

   m_g[1] = mod_p.reduce(g);

   bigint_monty_mul(z, m_g[1], m_R2_mod,
                    m_p.data(), m_p_words, m_mod_prime,
                    workspace.data());

   m_g[1] = z;

   const BigInt& x = m_g[1];

   for(size_t i = 2; i != m_g.size(); ++i)
      {
      const BigInt& y = m_g[i-1];

      bigint_monty_mul(z, x, y, m_p.data(), m_p_words, m_mod_prime,
                       workspace.data());

      m_g[i] = z;
      m_g[i].shrink_to_fit();
      m_g[i].grow_to(m_p_words);
      }
   }

Example #2

File: powm_mnt.cpp Project: jurajsomorovsky/botan

/*
* Set the base
*/
void Montgomery_Exponentiator::set_base(const BigInt& base)
   {
   m_window_bits = Power_Mod::window_bits(m_exp.bits(), base.bits(), m_hints);

   m_g.resize((1 << m_window_bits));

   BigInt z(BigInt::Positive, 2 * (m_mod_words + 1));
   secure_vector<word> workspace(z.size());

   m_g[0] = 1;

   bigint_monty_mul(z, m_g[0], m_R2_mod,
                    m_modulus.data(), m_mod_words, m_mod_prime,
                    workspace.data());
   m_g[0] = z;

   m_g[1] = (base >= m_modulus) ? (base % m_modulus) : base;

   bigint_monty_mul(z, m_g[1], m_R2_mod,
                    m_modulus.data(), m_mod_words, m_mod_prime,
                    workspace.data());

   m_g[1] = z;

   const BigInt& x = m_g[1];

   for(size_t i = 2; i != m_g.size(); ++i)
      {
      const BigInt& y = m_g[i-1];

      bigint_monty_mul(z, x, y, m_modulus.data(), m_mod_words, m_mod_prime,
                       workspace.data());

      m_g[i] = z;
      }
   }

Example #3

File: powm_mnt.cpp Project: jurajsomorovsky/botan

/*
* Compute the result
*/
BigInt Montgomery_Exponentiator::execute() const
   {
   const size_t exp_nibbles = (m_exp_bits + m_window_bits - 1) / m_window_bits;

   BigInt x = m_R_mod;

   const size_t z_size = 2*(m_mod_words + 1);

   BigInt z(BigInt::Positive, z_size);
   secure_vector<word> workspace(z.size());

   for(size_t i = exp_nibbles; i > 0; --i)
      {
      for(size_t k = 0; k != m_window_bits; ++k)
         {
         bigint_monty_sqr(z, x, m_modulus.data(), m_mod_words, m_mod_prime,
                          workspace.data());

         x = z;
         }

      const u32bit nibble = m_exp.get_substring(m_window_bits*(i-1), m_window_bits);

      const BigInt& y = m_g[nibble];

      bigint_monty_mul(z, x, y,
                       m_modulus.data(), m_mod_words, m_mod_prime,
                       workspace.data());

      x = z;
      }

   x.grow_to(2*m_mod_words + 1);

   bigint_monty_redc(x.mutable_data(),
                     m_modulus.data(), m_mod_words, m_mod_prime,
                     workspace.data());

   return x;
   }

Example #4

File: point_gfp.cpp Project: BenjaminSchiborr/safe

// Montgomery multiplication
void PointGFp::monty_mult(BigInt& z, const BigInt& x, const BigInt& y) const
   {
   //assert(&z != &x && &z != &y);

   if(x.is_zero() || y.is_zero())
      {
      z = 0;
      return;
      }

   const BigInt& p = curve.get_p();
   const size_t p_size = curve.get_p_words();
   const word p_dash = curve.get_p_dash();

   SecureVector<word>& z_reg = z.get_reg();
   z_reg.resize(2*p_size+1);
   zeroise(z_reg);

   bigint_monty_mul(&z_reg[0], z_reg.size(),
                    x.data(), x.size(), x.sig_words(),
                    y.data(), y.size(), y.sig_words(),
                    p.data(), p_size, p_dash,
                    &ws[0]);
   }