/*
* CECPQ1 (x25519 + NewHope)
* (C) 2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/cecpq1.h>
#include <botan/newhope.h>
#include <botan/curve25519.h>
#include <botan/rng.h>

namespace Botan {

void CECPQ1_offer(uint8_t send[CECPQ1_OFFER_BYTES],
                  CECPQ1_key* offer_key_output,
                  RandomNumberGenerator& rng)
   {
   offer_key_output->m_x25519 = rng.random_vec(32);
   curve25519_basepoint(send, offer_key_output->m_x25519.data());

   newhope_keygen(send + 32, &offer_key_output->m_newhope,
                  rng, Newhope_Mode::BoringSSL);
   }

void CECPQ1_accept(uint8_t shared_key[CECPQ1_SHARED_KEY_BYTES],
                   uint8_t send[CECPQ1_ACCEPT_BYTES],
                   const uint8_t received[CECPQ1_OFFER_BYTES],
                   RandomNumberGenerator& rng)
   {
   secure_vector<uint8_t> x25519_key = rng.random_vec(32);

   curve25519_basepoint(send, x25519_key.data());

   curve25519_donna(shared_key, x25519_key.data(), received);

   newhope_sharedb(shared_key + 32, send + 32, received + 32,
                   rng, Newhope_Mode::BoringSSL);
   }

void CECPQ1_finish(uint8_t shared_key[CECPQ1_SHARED_KEY_BYTES],
                   const CECPQ1_key& offer_key,
                   const uint8_t received[CECPQ1_ACCEPT_BYTES])
   {
   curve25519_donna(shared_key, offer_key.m_x25519.data(), received);

   newhope_shareda(shared_key + 32, &offer_key.m_newhope, received + 32,
                   Newhope_Mode::BoringSSL);
   }

}