/*
* (C) 2014 cryptosource GmbH
* (C) 2014 Falko Strenzke fstrenzke@cryptosource.de
* (C) 2014,2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include "tests.h"

#include <botan/pubkey.h>
#include <botan/ecdsa.h>
#include <botan/rsa.h>
#include <botan/x509cert.h>
#include <botan/oids.h>
#include <botan/mceliece.h>
#include <botan/mce_kem.h>
#include <botan/mceies.h>
#include <botan/loadstor.h>

#include <botan/hex.h>

#include <iostream>
#include <memory>

using namespace Botan;

#define CHECK_MESSAGE(expr, print)  do {if(!(expr)) {std::cout << print << "\n"; return 1;} }while(0)
#define CHECK(expr) do {if(!(expr)) { std::cout << #expr << "\n"; return 1; } }while(0)

namespace {

const size_t MCE_RUNS = 5;

size_t test_mceliece_message_parts(RandomNumberGenerator& rng, size_t code_length, size_t error_weight)
   {
   secure_vector<gf2m> err_pos1 = create_random_error_positions(code_length, error_weight, rng);
   secure_vector<byte> message1((code_length+7)/8);
   rng.randomize(&message1[0], message1.size() - 1);
   mceliece_message_parts parts1(err_pos1, message1, code_length);
   secure_vector<byte> err_vec1 = parts1.get_error_vector();

   secure_vector<byte> concat1 = parts1.get_concat();

   mceliece_message_parts parts2( &concat1[0], concat1.size(), code_length);

   secure_vector<byte> err_vec2 = parts2.get_error_vector();
   if(err_vec1 != err_vec2)
      {
      std::cout << "error with error vector from message parts" << std::endl;
      return 1;
      }

   secure_vector<byte> message2 = parts2.get_message_word();
   if(message1 != message2)
      {
      std::cout << "error with message word from message parts" << std::endl;
      return 1;
      }

   return 0;
   }

size_t test_mceliece_kem(const McEliece_PrivateKey& sk,
                         const McEliece_PublicKey& pk,
                         RandomNumberGenerator& rng)
   {
   size_t fails = 0;

   McEliece_KEM_Encryptor pub_op(pk);
   McEliece_KEM_Decryptor priv_op(sk);

   for(size_t i = 0; i != MCE_RUNS; i++)
      {
      const std::pair<secure_vector<byte>,secure_vector<byte> > ciphertext__sym_key = pub_op.encrypt(rng);
      const secure_vector<byte>& ciphertext = ciphertext__sym_key.first;
      const secure_vector<byte>& sym_key_encr = ciphertext__sym_key.second;

      const secure_vector<byte> sym_key_decr = priv_op.decrypt(&ciphertext[0], ciphertext.size());

      if(sym_key_encr != sym_key_decr)
         {
         std::cout << "mce KEM test failed, error during encryption/decryption" << std::endl;
         ++fails;
         }

#if 0
         // takes a long time:
         for(size_t j = 0; j < code_length; j++)
            {
            // flip the j-th bit in the ciphertext
            secure_vector<byte> wrong_ct(ciphertext);
            size_t byte_pos = j/8;
            size_t bit_pos = j % 8;
            wrong_ct[byte_pos] ^= 1 << bit_pos;
            try
               {
               secure_vector<byte> decrypted = priv_op.decrypt(&wrong_ct[0], wrong_ct.size());
               }
            catch(const Integrity_Failure)
               {
               continue;
               }
            std::cout << "manipulation in ciphertext not detected" << std::endl;
            err_cnt++;
            }
#endif

      }

   return fails;
   }

size_t test_mceliece_raw(const McEliece_PrivateKey& sk,
                         const McEliece_PublicKey& pk,
                         RandomNumberGenerator& rng)
   {
   const size_t code_length = pk.get_code_length();
   McEliece_Private_Operation priv_op(sk);
   McEliece_Public_Operation pub_op(pk, code_length);
   size_t err_cnt = 0;

   for(size_t i = 0; i != MCE_RUNS; i++)
      {
      secure_vector<byte> plaintext((pk.get_message_word_bit_length()+7)/8);
      rng.randomize(&plaintext[0], plaintext.size() - 1);
      secure_vector<gf2m> err_pos = create_random_error_positions(code_length, pk.get_t(), rng);


      mceliece_message_parts parts(err_pos, plaintext, code_length);
      secure_vector<byte> message_and_error_input = parts.get_concat();
      secure_vector<byte> ciphertext = pub_op.encrypt(&message_and_error_input[0], message_and_error_input.size(), rng);
      //std::cout << "ciphertext byte length = " << ciphertext.size() << std::endl;
      secure_vector<byte> message_and_error_output = priv_op.decrypt(&ciphertext[0], ciphertext.size() );
      if(message_and_error_input != message_and_error_output)
         {
         mceliece_message_parts combined(&message_and_error_input[0], message_and_error_input.size(), code_length);
         secure_vector<byte> orig_pt = combined.get_message_word();
         secure_vector<byte> orig_ev = combined.get_error_vector();

         mceliece_message_parts decr_combined(&message_and_error_output[0], message_and_error_output.size(), code_length);
         secure_vector<byte> decr_pt = decr_combined.get_message_word();
         secure_vector<byte> decr_ev = decr_combined.get_error_vector();
         std::cout << "ciphertext = " << hex_encode(ciphertext) << std::endl;
         std::cout << "original      plaintext = " << hex_encode(orig_pt) << std::endl;
         std::cout << "original   error vector = " << hex_encode(orig_ev) << std::endl;
         std::cout << "decrypted     plaintext = " << hex_encode(decr_pt) << std::endl;
         std::cout << "decrypted  error vector = " << hex_encode(decr_ev) << std::endl;
         err_cnt++;
         std::cout << "mce test failed, error during encryption/decryption" << std::endl;
         std::cout << "err pos during encryption = ";
         for(size_t j = 0; j < err_pos.size(); j++) std::printf("%u, ", err_pos[j]);
         printf("\n");
         return 1;
         continue;
         }
      }

   return err_cnt;
   }

size_t test_mceies(const McEliece_PrivateKey& sk,
                   const McEliece_PublicKey& pk,
                   RandomNumberGenerator& rng)
   {

   size_t fails = 0;

   for(size_t i = 0; i != 5; ++i)
      {
      byte ad[8];
      store_be(static_cast<u64bit>(i), ad);
      const size_t ad_len = sizeof(ad);

      const secure_vector<byte> pt = rng.random_vec(rng.next_byte());
      const secure_vector<byte> ct = mceies_encrypt(pk, pt, ad, ad_len, rng);
      const secure_vector<byte> dec = mceies_decrypt(sk, ct, ad, ad_len);

      if(pt != dec)
         {
         std::cout << "MCEIES " << hex_encode(pt) << " != " << hex_encode(dec) << "\n";
         ++fails;
         }

      secure_vector<byte> bad_ct = ct;
      for(size_t j = 0; j != 2; ++j)
         {
         bad_ct = ct;

         byte nonzero = 0;
         while(nonzero == 0)
            nonzero = rng.next_byte();

         bad_ct[rng.next_byte() % bad_ct.size()] ^= nonzero;

         try
            {
            mceies_decrypt(sk, bad_ct, ad, ad_len);
            std::cout << "Successfully decrypted manipulated ciphertext!\n";
            ++fails;
            }
         catch(std::exception& e) { /* Yay */ }

         bad_ct[i] ^= nonzero;
         }
      }

   return fails;
   }

}

size_t test_mceliece()
   {
   auto& rng = test_rng();

   size_t  fails = 0;
   size_t params__n__t_min_max[] = {
      256, 5, 15,
      512, 5, 33,
      1024, 15, 35,
      2048, 33, 50,
      2960, 50, 56,
      6624, 110, 115
   };

   size_t tests = 0;

   for(size_t i = 0; i < sizeof(params__n__t_min_max)/sizeof(params__n__t_min_max[0]); i+=3)
      {
      size_t code_length = params__n__t_min_max[i];
      for(size_t t = params__n__t_min_max[i+1]; t <= params__n__t_min_max[i+2]; t++)
         {
         //std::cout << "testing parameters n = " << code_length << ", t = " << t << std::endl;

         try
            {
            fails += test_mceliece_message_parts(rng, code_length, t);
            }
         catch(std::exception& e)
            {
            std::cout << e.what();
            fails++;
            }

         McEliece_PrivateKey sk1(rng, code_length, t);
         const McEliece_PublicKey& pk1 = sk1;

         const std::vector<byte> pk_enc = pk1.x509_subject_public_key();
         const secure_vector<byte> sk_enc = sk1.pkcs8_private_key();

         McEliece_PublicKey pk(pk_enc);
         McEliece_PrivateKey sk(sk_enc);

         if(pk1 != pk)
            {
            std::cout << "Decoded McEliece public key differs from original one" << std::endl;
            ++fails;
            }

         if(sk1 != sk)
            {
            std::cout << "Decoded McEliece private key differs from original one" << std::endl;
            ++fails;
            }

         if(!sk.check_key(rng, false))
            {
            std::cout << "Error calling check key on McEliece key" << std::endl;
            ++fails;
            }

         try
            {
            fails += test_mceliece_raw(sk, pk, rng);
            }
         catch(std::exception& e)
            {
            std::cout << e.what();
            fails++;
            }

         try
            {
            fails += test_mceliece_kem(sk, pk, rng);
            }
         catch(std::exception& e)
            {
            std::cout << e.what();
            fails++;
            }

         try
            {
            fails += test_mceies(sk, pk, rng);
            }
         catch(std::exception& e)
            {
            std::cout << e.what();
            fails++;
            }

         tests += 4;
         }
      }

   test_report("McEliece", tests, fails);
   return fails;
   }