/*
* MD2
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/

#include <botan/md2.h>
#include <botan/internal/xor_buf.h>

namespace Botan {

/**
* MD2 Compression Function
*/
void MD2::hash(const byte input[])
   {
   static const byte SBOX[256] = {
      0x29, 0x2E, 0x43, 0xC9, 0xA2, 0xD8, 0x7C, 0x01, 0x3D, 0x36, 0x54, 0xA1,
      0xEC, 0xF0, 0x06, 0x13, 0x62, 0xA7, 0x05, 0xF3, 0xC0, 0xC7, 0x73, 0x8C,
      0x98, 0x93, 0x2B, 0xD9, 0xBC, 0x4C, 0x82, 0xCA, 0x1E, 0x9B, 0x57, 0x3C,
      0xFD, 0xD4, 0xE0, 0x16, 0x67, 0x42, 0x6F, 0x18, 0x8A, 0x17, 0xE5, 0x12,
      0xBE, 0x4E, 0xC4, 0xD6, 0xDA, 0x9E, 0xDE, 0x49, 0xA0, 0xFB, 0xF5, 0x8E,
      0xBB, 0x2F, 0xEE, 0x7A, 0xA9, 0x68, 0x79, 0x91, 0x15, 0xB2, 0x07, 0x3F,
      0x94, 0xC2, 0x10, 0x89, 0x0B, 0x22, 0x5F, 0x21, 0x80, 0x7F, 0x5D, 0x9A,
      0x5A, 0x90, 0x32, 0x27, 0x35, 0x3E, 0xCC, 0xE7, 0xBF, 0xF7, 0x97, 0x03,
      0xFF, 0x19, 0x30, 0xB3, 0x48, 0xA5, 0xB5, 0xD1, 0xD7, 0x5E, 0x92, 0x2A,
      0xAC, 0x56, 0xAA, 0xC6, 0x4F, 0xB8, 0x38, 0xD2, 0x96, 0xA4, 0x7D, 0xB6,
      0x76, 0xFC, 0x6B, 0xE2, 0x9C, 0x74, 0x04, 0xF1, 0x45, 0x9D, 0x70, 0x59,
      0x64, 0x71, 0x87, 0x20, 0x86, 0x5B, 0xCF, 0x65, 0xE6, 0x2D, 0xA8, 0x02,
      0x1B, 0x60, 0x25, 0xAD, 0xAE, 0xB0, 0xB9, 0xF6, 0x1C, 0x46, 0x61, 0x69,
      0x34, 0x40, 0x7E, 0x0F, 0x55, 0x47, 0xA3, 0x23, 0xDD, 0x51, 0xAF, 0x3A,
      0xC3, 0x5C, 0xF9, 0xCE, 0xBA, 0xC5, 0xEA, 0x26, 0x2C, 0x53, 0x0D, 0x6E,
      0x85, 0x28, 0x84, 0x09, 0xD3, 0xDF, 0xCD, 0xF4, 0x41, 0x81, 0x4D, 0x52,
      0x6A, 0xDC, 0x37, 0xC8, 0x6C, 0xC1, 0xAB, 0xFA, 0x24, 0xE1, 0x7B, 0x08,
      0x0C, 0xBD, 0xB1, 0x4A, 0x78, 0x88, 0x95, 0x8B, 0xE3, 0x63, 0xE8, 0x6D,
      0xE9, 0xCB, 0xD5, 0xFE, 0x3B, 0x00, 0x1D, 0x39, 0xF2, 0xEF, 0xB7, 0x0E,
      0x66, 0x58, 0xD0, 0xE4, 0xA6, 0x77, 0x72, 0xF8, 0xEB, 0x75, 0x4B, 0x0A,
      0x31, 0x44, 0x50, 0xB4, 0x8F, 0xED, 0x1F, 0x1A, 0xDB, 0x99, 0x8D, 0x33,
      0x9F, 0x11, 0x83, 0x14 };

   X.copy(16, input, hash_block_size());
   xor_buf(&X[32], &X[0], &X[16], hash_block_size());
   byte T = 0;

   for(size_t i = 0; i != 18; ++i)
      {
      for(size_t k = 0; k != 48; k += 8)
         {
         T = X[k  ] ^= SBOX[T]; T = X[k+1] ^= SBOX[T];
         T = X[k+2] ^= SBOX[T]; T = X[k+3] ^= SBOX[T];
         T = X[k+4] ^= SBOX[T]; T = X[k+5] ^= SBOX[T];
         T = X[k+6] ^= SBOX[T]; T = X[k+7] ^= SBOX[T];
         }

      T += static_cast<byte>(i);
      }

   T = checksum[15];
   for(size_t i = 0; i != hash_block_size(); ++i)
      T = checksum[i] ^= SBOX[input[i] ^ T];
   }

/**
* Update the hash
*/
void MD2::add_data(const byte input[], size_t length)
   {
   buffer.copy(position, input, length);

   if(position + length >= hash_block_size())
      {
      hash(&buffer[0]);
      input += (hash_block_size() - position);
      length -= (hash_block_size() - position);
      while(length >= hash_block_size())
         {
         hash(input);
         input += hash_block_size();
         length -= hash_block_size();
         }
      buffer.copy(input, length);
      position = 0;
      }
   position += length;
   }

/**
* Finalize a MD2 Hash
*/
void MD2::final_result(byte output[])
   {
   for(size_t i = position; i != hash_block_size(); ++i)
      buffer[i] = static_cast<byte>(hash_block_size() - position);

   hash(&buffer[0]);
   hash(&checksum[0]);
   copy_mem(output, &X[0], output_length());
   clear();
   }

/**
* Clear memory of sensitive data
*/
void MD2::clear()
   {
   zeroise(X);
   zeroise(checksum);
   zeroise(buffer);
   position = 0;
   }

}