/*
* GOST 28147-89
* (C) 1999-2009,2011 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/internal/gost_28147.h>
#include <botan/exceptn.h>
#include <botan/internal/loadstor.h>
#include <botan/internal/rotate.h>

namespace Botan {

uint8_t GOST_28147_89_Params::sbox_entry(size_t row, size_t col) const
   {
   const uint8_t x = m_sboxes[4 * col + (row / 2)];
   return (row % 2 == 0) ? (x >> 4) : (x & 0x0F);
   }

uint8_t GOST_28147_89_Params::sbox_pair(size_t row, size_t col) const
   {
   const uint8_t x = m_sboxes[4 * (col % 16) + row];
   const uint8_t y = m_sboxes[4 * (col / 16) + row];
   return (x >> 4) | (y << 4);
   }

GOST_28147_89_Params::GOST_28147_89_Params(const std::string& n) : m_name(n)
   {
   // Encoded in the packed fromat from RFC 4357

   // GostR3411_94_TestParamSet (OID 1.2.643.2.2.31.0)
   static const uint8_t GOST_R_3411_TEST_PARAMS[64] = {
      0x4E, 0x57, 0x64, 0xD1, 0xAB, 0x8D, 0xCB, 0xBF, 0x94, 0x1A, 0x7A,
      0x4D, 0x2C, 0xD1, 0x10, 0x10, 0xD6, 0xA0, 0x57, 0x35, 0x8D, 0x38,
      0xF2, 0xF7, 0x0F, 0x49, 0xD1, 0x5A, 0xEA, 0x2F, 0x8D, 0x94, 0x62,
      0xEE, 0x43, 0x09, 0xB3, 0xF4, 0xA6, 0xA2, 0x18, 0xC6, 0x98, 0xE3,
      0xC1, 0x7C, 0xE5, 0x7E, 0x70, 0x6B, 0x09, 0x66, 0xF7, 0x02, 0x3C,
      0x8B, 0x55, 0x95, 0xBF, 0x28, 0x39, 0xB3, 0x2E, 0xCC };

   // GostR3411-94-CryptoProParamSet (OID 1.2.643.2.2.31.1)
   static const uint8_t GOST_R_3411_CRYPTOPRO_PARAMS[64] = {
      0xA5, 0x74, 0x77, 0xD1, 0x4F, 0xFA, 0x66, 0xE3, 0x54, 0xC7, 0x42,
      0x4A, 0x60, 0xEC, 0xB4, 0x19, 0x82, 0x90, 0x9D, 0x75, 0x1D, 0x4F,
      0xC9, 0x0B, 0x3B, 0x12, 0x2F, 0x54, 0x79, 0x08, 0xA0, 0xAF, 0xD1,
      0x3E, 0x1A, 0x38, 0xC7, 0xB1, 0x81, 0xC6, 0xE6, 0x56, 0x05, 0x87,
      0x03, 0x25, 0xEB, 0xFE, 0x9C, 0x6D, 0xF8, 0x6D, 0x2E, 0xAB, 0xDE,
      0x20, 0xBA, 0x89, 0x3C, 0x92, 0xF8, 0xD3, 0x53, 0xBC };

   if(m_name == "R3411_94_TestParam")
      m_sboxes = GOST_R_3411_TEST_PARAMS;
   else if(m_name == "R3411_CryptoPro")
      m_sboxes = GOST_R_3411_CRYPTOPRO_PARAMS;
   else
      throw Invalid_Argument("GOST_28147_89_Params: Unknown " + m_name);
   }

/*
* GOST Constructor
*/
GOST_28147_89::GOST_28147_89(const GOST_28147_89_Params& param) :
   m_SBOX(1024),
   m_name("GOST-28147-89(" + param.param_name() + ")")
   {
   // Convert the parallel 4x4 sboxes into larger word-based sboxes

   for(size_t i = 0; i != 256; ++i)
      {
      m_SBOX[i    ] = rotl<11, uint32_t>(param.sbox_pair(0, i));
      m_SBOX[i+256] = rotl<19, uint32_t>(param.sbox_pair(1, i));
      m_SBOX[i+512] = rotl<27, uint32_t>(param.sbox_pair(2, i));
      m_SBOX[i+768] = rotl< 3, uint32_t>(param.sbox_pair(3, i));
      }
   }

std::string GOST_28147_89::name() const
   {
   return m_name;
   }

namespace {

/*
* Two rounds of GOST
*/
template<size_t R1, size_t R2>
void GOST_ROUND2(uint32_t& N1, uint32_t& N2,
                 const std::vector<uint32_t>& S,
                 const secure_vector<uint32_t>& EK)
   {
   const uint32_t T0 = N1 + EK[R1];
   N2 ^= S[get_byte<3>(T0)] |
         S[get_byte<2>(T0)+256] |
         S[get_byte<1>(T0)+512] |
         S[get_byte<0>(T0)+768];

   const uint32_t T1 = N2 + EK[R2];
   N1 ^= S[get_byte<3>(T1)] |
         S[get_byte<2>(T1)+256] |
         S[get_byte<1>(T1)+512] |
         S[get_byte<0>(T1)+768];
   }

}

/*
* GOST Encryption
*/
void GOST_28147_89::encrypt_n(const uint8_t in[], uint8_t out[], size_t blocks) const
   {
   verify_key_set(m_EK.empty() == false);

   for(size_t i = 0; i != blocks; ++i)
      {
      uint32_t N1 = load_le<uint32_t>(in, 0);
      uint32_t N2 = load_le<uint32_t>(in, 1);

      for(size_t j = 0; j != 3; ++j)
         {
         GOST_ROUND2<0, 1>(N1, N2, m_SBOX, m_EK);
         GOST_ROUND2<2, 3>(N1, N2, m_SBOX, m_EK);
         GOST_ROUND2<4, 5>(N1, N2, m_SBOX, m_EK);
         GOST_ROUND2<6, 7>(N1, N2, m_SBOX, m_EK);
         }

      GOST_ROUND2<7, 6>(N1, N2, m_SBOX, m_EK);
      GOST_ROUND2<5, 4>(N1, N2, m_SBOX, m_EK);
      GOST_ROUND2<3, 2>(N1, N2, m_SBOX, m_EK);
      GOST_ROUND2<1, 0>(N1, N2, m_SBOX, m_EK);

      store_le(out, N2, N1);

      in += BLOCK_SIZE;
      out += BLOCK_SIZE;
      }
   }

/*
* GOST Decryption
*/
void GOST_28147_89::decrypt_n(const uint8_t in[], uint8_t out[], size_t blocks) const
   {
   verify_key_set(m_EK.empty() == false);

   for(size_t i = 0; i != blocks; ++i)
      {
      uint32_t N1 = load_le<uint32_t>(in, 0);
      uint32_t N2 = load_le<uint32_t>(in, 1);

      GOST_ROUND2<0, 1>(N1, N2, m_SBOX, m_EK);
      GOST_ROUND2<2, 3>(N1, N2, m_SBOX, m_EK);
      GOST_ROUND2<4, 5>(N1, N2, m_SBOX, m_EK);
      GOST_ROUND2<6, 7>(N1, N2, m_SBOX, m_EK);

      for(size_t j = 0; j != 3; ++j)
         {
         GOST_ROUND2<7, 6>(N1, N2, m_SBOX, m_EK);
         GOST_ROUND2<5, 4>(N1, N2, m_SBOX, m_EK);
         GOST_ROUND2<3, 2>(N1, N2, m_SBOX, m_EK);
         GOST_ROUND2<1, 0>(N1, N2, m_SBOX, m_EK);
         }

      store_le(out, N2, N1);
      in += BLOCK_SIZE;
      out += BLOCK_SIZE;
      }
   }

/*
* GOST Key Schedule
*/
void GOST_28147_89::key_schedule(const uint8_t key[], size_t /*length*/)
   {
   m_EK.resize(8);
   for(size_t i = 0; i != 8; ++i)
      m_EK[i] = load_le<uint32_t>(key, i);
   }

void GOST_28147_89::clear()
   {
   zap(m_EK);
   }

}