Running C Code in Matlab using MEX

#include "mex.h"
#include "stdafx.h"
#include <stdio.h>
#include "blowfish.h"
#include <iostream>
#include <sstream>
#include <cstdlib>

void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
//void main(void) 
{
  unsigned long L = 1, R = 2;
  BLOWFISH_CTX ctx;

  unsigned long message_left;
  unsigned long message_right;
  int block_len;
  unsigned char ciphertext_buffer[256];
  unsigned char *ciphertext_string = &ciphertext_buffer[0];
  int ciphertext_len = 0;

  using namespace std;

  string input = "";
  string inputkey = "";
  string inputDkey = "";

  cout << "Please enter a valid message:\n>";
  getline(cin, input);
  cout << "Your message: " << input << endl << endl;

  cout << "Please enter a valid key:\n>";
  getline(cin, inputkey);
  cout << "Your key: " << inputkey << endl << endl;

  /*Blowfish_Init (&ctx, (unsigned char*)"TESTKEY", 7);
  Blowfish_Init (&ctx, (unsigned char*)(input.c_str()), 7);*/
  //Blowfish_Encrypt(&ctx, &L, &R);

  /* must be less than 56 bytes */
  //char *key = "a random number string would be a better key";

  /*const char* key = "TESTKEY";*/
  const char* key = inputkey.c_str();

  int keylen = strlen(key);

  /*char const* plaintext_string = "this is our message";*/

  char const* plaintext_string = input.c_str();

  // explicitly cast to 'unsigned char*'
  //unsigned char* in = reinterpret_cast<unsigned char*>(key);

  int plaintext_len = strlen(plaintext_string);
  Blowfish_Init(&ctx, (unsigned char*)key, keylen);

  /* encrypt the plaintext message string */
  mexPrintf("Encrypted message string is: ");

  while (plaintext_len)
  {
    message_left = message_right = 0UL;

    /* crack the message string into a 64-bit block (ok, really two 32-bit blocks); pad with zeros if necessary */
    for (block_len = 0; block_len < 4; block_len++)
    {
      message_left = message_left << 8;
      if (plaintext_len)
      {
        message_left += *plaintext_string++;
        plaintext_len--;
      }
      else message_left += 0;
    }
    for (block_len = 0; block_len < 4; block_len++)
    {
      message_right = message_right << 8;
      if (plaintext_len)
      {
        message_right += *plaintext_string++;
        plaintext_len--;
      }
      else message_right += 0;
    }
    /* encrypt and print the results */
    Blowfish_Encrypt(&ctx, &message_left, &message_right);
    mexPrintf("%lx%lx", message_left, message_right);
    //fflush(stdout);

    /* save the results for decryption below */
    *ciphertext_string++ = (unsigned char)(message_left >> 24);
    *ciphertext_string++ = (unsigned char)(message_left >> 16);
    *ciphertext_string++ = (unsigned char)(message_left >> 8);
    *ciphertext_string++ = (unsigned char)message_left;
    *ciphertext_string++ = (unsigned char)(message_right >> 24);
    *ciphertext_string++ = (unsigned char)(message_right >> 16);
    *ciphertext_string++ = (unsigned char)(message_right >> 8);
    *ciphertext_string++ = (unsigned char)message_right;
    ciphertext_len += 8;

  }

  mexPrintf("\n\n");

  cout << "Please enter a valid Decryption key:\n>";
  //mexPrintf("Please enter a valid Decryption key:\n");
  getline(cin, inputDkey);
  //scanf_s("%s",inputDkey);
  cout << "Your key: " << inputDkey << endl << endl;
  //mexPrintf("Your key:%s",inputDkey);

  const char* Dkey = inputDkey.c_str();

  int Dkeylen = strlen(Dkey);
  Blowfish_Init(&ctx, (unsigned char*)Dkey, keylen);
  /* reverse the process */
  mexPrintf("Decrypted message string is: ");

  ciphertext_string = &ciphertext_buffer[0];
  while (ciphertext_len)
  {
    message_left = message_right = 0UL;

    for (block_len = 0; block_len < 4; block_len++)
    {
      message_left = message_left << 8;
      message_left += *ciphertext_string++;
      if (ciphertext_len)
        ciphertext_len--;
    }
    for (block_len = 0; block_len < 4; block_len++)
    {
      message_right = message_right << 8;
      message_right += *ciphertext_string++;
      if (ciphertext_len)
        ciphertext_len--;
    }

    Blowfish_Decrypt(&ctx, &message_left, &message_right);

    /* if plaintext message string padded, extra zeros here */

    mexPrintf("%c%c%c%c%c%c%c%c",
      (int)(message_left >> 24), (int)(message_left >> 16),
      (int)(message_left >> 8), (int)(message_left),
      (int)(message_right >> 24), (int)(message_right >> 16),
      (int)(message_right >> 8), (int)(message_right));
  }

  mexPrintf("\n");
}

Does anyone know how to run this code in Matlab? I have trouble getting the output in Matlab command window.

Answer 1

[Walter Roberson]

See http://www.mathworks.com/matlabcentral/answers/132527#answer_178816