1 files changed, 248 insertions, 0 deletions
diff --git a/src/libs/3rdparty/botan/src/lib/math/numbertheory/monty_exp.cpp b/src/libs/3rdparty/botan/src/lib/math/numbertheory/monty_exp.cpp
new file mode 100644
index 0000000000..5674920915
--- /dev/null
+++ b/src/libs/3rdparty/botan/src/lib/math/numbertheory/monty_exp.cpp
@@ -0,0 +1,248 @@
+/*
+* Montgomery Exponentiation
+* (C) 1999-2010,2012,2018 Jack Lloyd
+*     2016 Matthias Gierlings
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/internal/monty_exp.h>
+#include <botan/internal/ct_utils.h>
+#include <botan/internal/rounding.h>
+#include <botan/numthry.h>
+#include <botan/reducer.h>
+#include <botan/monty.h>
+
+namespace Botan {
+
+class Montgomery_Exponentation_State
+   {
+   public:
+      Montgomery_Exponentation_State(std::shared_ptr<const Montgomery_Params> params,
+                                     const BigInt& g,
+                                     size_t window_bits,
+                                     bool const_time);
+
+      BigInt exponentiation(const BigInt& k, size_t max_k_bits) const;
+
+      BigInt exponentiation_vartime(const BigInt& k) const;
+   private:
+      std::shared_ptr<const Montgomery_Params> m_params;
+      std::vector<Montgomery_Int> m_g;
+      size_t m_window_bits;
+      bool m_const_time;
+   };
+
+Montgomery_Exponentation_State::Montgomery_Exponentation_State(std::shared_ptr<const Montgomery_Params> params,
+                                                               const BigInt& g,
+                                                               size_t window_bits,
+                                                               bool const_time) :
+   m_params(params),
+   m_window_bits(window_bits == 0 ? 4 : window_bits),
+   m_const_time(const_time)
+   {
+   if(m_window_bits < 1 || m_window_bits > 12) // really even 8 is too large ...
+      throw Invalid_Argument("Invalid window bits for Montgomery exponentiation");
+
+   const size_t window_size = (1U << m_window_bits);
+
+   m_g.reserve(window_size);
+
+   m_g.push_back(Montgomery_Int(m_params, m_params->R1(), false));
+
+   m_g.push_back(Montgomery_Int(m_params, g));
+
+   const Montgomery_Int& monty_g = m_g[1];
+
+   for(size_t i = 2; i != window_size; ++i)
+      {
+      m_g.push_back(monty_g * m_g[i - 1]);
+      }
+
+   // Resize each element to exactly p words
+   for(size_t i = 0; i != window_size; ++i)
+      {
+      m_g[i].fix_size();
+      if(const_time)
+         m_g[i].const_time_poison();
+      }
+   }
+
+namespace {
+
+void const_time_lookup(secure_vector<word>& output,
+                       const std::vector<Montgomery_Int>& g,
+                       size_t nibble)
+   {
+   const size_t words = output.size();
+
+   clear_mem(output.data(), output.size());
+
+   for(size_t i = 0; i != g.size(); ++i)
+      {
+      const secure_vector<word>& vec = g[i].repr().get_word_vector();
+
+      BOTAN_ASSERT(vec.size() >= words,
+                   "Word size as expected in const_time_lookup");
+
+      const word mask = CT::is_equal<word>(i, nibble);
+
+      for(size_t w = 0; w != words; ++w)
+         output[w] |= (mask & vec[w]);
+      }
+   }
+
+}
+
+BigInt Montgomery_Exponentation_State::exponentiation(const BigInt& scalar, size_t max_k_bits) const
+   {
+   BOTAN_DEBUG_ASSERT(scalar.bits() <= max_k_bits);
+   // TODO add a const-time implementation of above assert and use it in release builds
+
+   const size_t exp_nibbles = (max_k_bits + m_window_bits - 1) / m_window_bits;
+
+   if(exp_nibbles == 0)
+      return 1;
+
+   secure_vector<word> e_bits(m_params->p_words());
+   secure_vector<word> ws;
+
+   const_time_lookup(e_bits, m_g, scalar.get_substring(m_window_bits*(exp_nibbles-1), m_window_bits));
+   Montgomery_Int x(m_params, e_bits.data(), e_bits.size(), false);
+
+   for(size_t i = exp_nibbles - 1; i > 0; --i)
+      {
+      x.square_this_n_times(ws, m_window_bits);
+      const_time_lookup(e_bits, m_g, scalar.get_substring(m_window_bits*(i-1), m_window_bits));
+      x.mul_by(e_bits, ws);
+      }
+
+   x.const_time_unpoison();
+   return x.value();
+   }
+
+BigInt Montgomery_Exponentation_State::exponentiation_vartime(const BigInt& scalar) const
+   {
+   BOTAN_ASSERT_NOMSG(m_const_time == false);
+
+   const size_t exp_nibbles = (scalar.bits() + m_window_bits - 1) / m_window_bits;
+
+   secure_vector<word> ws;
+
+   if(exp_nibbles == 0)
+      return 1;
+
+   Montgomery_Int x = m_g[scalar.get_substring(m_window_bits*(exp_nibbles-1), m_window_bits)];
+
+   for(size_t i = exp_nibbles - 1; i > 0; --i)
+      {
+      x.square_this_n_times(ws, m_window_bits);
+
+      const uint32_t nibble = scalar.get_substring(m_window_bits*(i-1), m_window_bits);
+      if(nibble > 0)
+         x.mul_by(m_g[nibble], ws);
+      }
+
+   x.const_time_unpoison();
+   return x.value();
+   }
+
+std::shared_ptr<const Montgomery_Exponentation_State>
+monty_precompute(std::shared_ptr<const Montgomery_Params> params,
+                 const BigInt& g,
+                 size_t window_bits,
+                 bool const_time)
+   {
+   return std::make_shared<const Montgomery_Exponentation_State>(params, g, window_bits, const_time);
+   }
+
+BigInt monty_execute(const Montgomery_Exponentation_State& precomputed_state,
+                     const BigInt& k, size_t max_k_bits)
+   {
+   return precomputed_state.exponentiation(k, max_k_bits);
+   }
+
+BigInt monty_execute_vartime(const Montgomery_Exponentation_State& precomputed_state,
+                             const BigInt& k)
+   {
+   return precomputed_state.exponentiation_vartime(k);
+   }
+
+BigInt monty_multi_exp(std::shared_ptr<const Montgomery_Params> params_p,
+                       const BigInt& x_bn,
+                       const BigInt& z1,
+                       const BigInt& y_bn,
+                       const BigInt& z2)
+   {
+   if(z1.is_negative() || z2.is_negative())
+      throw Invalid_Argument("multi_exponentiate exponents must be positive");
+
+   const size_t z_bits = round_up(std::max(z1.bits(), z2.bits()), 2);
+
+   secure_vector<word> ws;
+
+   const Montgomery_Int one(params_p, params_p->R1(), false);
+   //const Montgomery_Int one(params_p, 1);
+
+   const Montgomery_Int x1(params_p, x_bn);
+   const Montgomery_Int x2 = x1.square(ws);
+   const Montgomery_Int x3 = x2.mul(x1, ws);
+
+   const Montgomery_Int y1(params_p, y_bn);
+   const Montgomery_Int y2 = y1.square(ws);
+   const Montgomery_Int y3 = y2.mul(y1, ws);
+
+   const Montgomery_Int y1x1 = y1.mul(x1, ws);
+   const Montgomery_Int y1x2 = y1.mul(x2, ws);
+   const Montgomery_Int y1x3 = y1.mul(x3, ws);
+
+   const Montgomery_Int y2x1 = y2.mul(x1, ws);
+   const Montgomery_Int y2x2 = y2.mul(x2, ws);
+   const Montgomery_Int y2x3 = y2.mul(x3, ws);
+
+   const Montgomery_Int y3x1 = y3.mul(x1, ws);
+   const Montgomery_Int y3x2 = y3.mul(x2, ws);
+   const Montgomery_Int y3x3 = y3.mul(x3, ws);
+
+   const Montgomery_Int* M[16] = {
+      &one,
+      &x1,                    // 0001
+      &x2,                    // 0010
+      &x3,                    // 0011
+      &y1,                    // 0100
+      &y1x1,
+      &y1x2,
+      &y1x3,
+      &y2,                    // 1000
+      &y2x1,
+      &y2x2,
+      &y2x3,
+      &y3,                    // 1100
+      &y3x1,
+      &y3x2,
+      &y3x3
+   };
+
+   Montgomery_Int H = one;
+
+   for(size_t i = 0; i != z_bits; i += 2)
+      {
+      if(i > 0)
+         {
+         H.square_this(ws);
+         H.square_this(ws);
+         }
+
+      const uint8_t z1_b = z1.get_substring(z_bits - i - 2, 2);
+      const uint8_t z2_b = z2.get_substring(z_bits - i - 2, 2);
+
+      const uint8_t z12 = (4*z2_b) + z1_b;
+
+      H.mul_by(*M[z12], ws);
+      }
+
+   return H.value();
+   }
+
+}
+