blowfish_test.mexw64 : fatal error LNK1120: 3 unresolved externals

[klun]

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Code C - [expand]
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#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*)(input.c_str()), 7);*/
    
    const char* key = inputkey.c_str();
 
    int keylen = strlen(key);
 
    char const* plaintext_string = input.c_str();
 
    int plaintext_len = strlen(plaintext_string);
    Blowfish_Init(&ctx, (unsigned char*)key, keylen);
 
    mexPrintf("Encrypted message string is: ");
 
 
    while (plaintext_len)
    {
        message_left = message_right = 0UL;
        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;
        }
        
        Blowfish_Encrypt(&ctx, &message_left, &message_right);
        mexPrintf("%lx%lx", message_left, message_right);
        
        *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>";
 
    getline(cin, inputDkey);
    
    cout << "Your key: " << inputDkey << endl << endl;
 
    const char* Dkey = inputDkey.c_str();
 
    int Dkeylen = strlen(Dkey);
    Blowfish_Init(&ctx, (unsigned char*)Dkey, keylen);
    
    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);
 
        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");
}

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Can anyone help me to look on this C code? I have included the mex.h in my code which I want this code to run in Matlab using MEX file. However I have not getting any output and keep getting the error shown below.

Error : blowfish_test.obj : error LNK2019: unresolved external symbol "void __cdecl Blowfish_Decrypt(struct BLOWFISH_CTX
*,unsigned long *,unsigned long *)" (?Blowfish_Decrypt@@YAXPEAUBLOWFISH_CTX@@PEAK1@Z) referenced in function mexFunction

 

[horace1]

you are making a call

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

but the linker cannot find a version Blowfish_Decrypt() with the paramters pointer to a BLOWFISH_CTX structure and two pointers to unsigned long

void __cdecl Blowfish_Decrypt(struct BLOWFISH_CTX*,unsigned long *,unsigned long *)

1. check you are calling it with the correct paramters
2. are you linking in the blowfish libraries?
the message : fatal error LNK1120: 3 unresolved externals indicates you have two other unresolved externals - are they Blowfish_Init() and Blowfish_Encrypt()?

 

[klun]

Yes sir you are absolutely right. Hence in this case, do I need to alter the pointer so that it can be called in Matlab? And by using MEX function, I thought it supposed to called C code in Matlab directly without need to change anything? Am I right?

 

[horace1]

it looks like you are not linking the blowfish library correctly
is it a Matlab, C or C++ library?
if C++ are you linking blowfish.cpp at compile time, e.g.

mex blowfish_test.cpp blowfish.cpp

can you post blowfish.h?

 

[klun]

Blowfish.h

typedef struct {
unsigned long P[16 + 2];
unsigned long S[4][256];
} BLOWFISH_CTX;

void Blowfish_Init(BLOWFISH_CTX *ctx, unsigned char *key, int keyLen);
void Blowfish_Encrypt(BLOWFISH_CTX *ctx, unsigned long *xl, unsigned long *xr);
void Blowfish_Decrypt(BLOWFISH_CTX *ctx, unsigned long *xl, unsigned long *xr);



Yea. I did called my C code from Matlab using mex -v blowfish_test.cpp blowfish.cpp. In this instant, I need to call blowfish.h too? It will show an error saying .h is an unrecognised file sir.

 

[horace1]

check that the function names and parameter number and types are the same in blowfish.cpp and blowfish.h
does blowfish.cpp include blowfish.h?
you don't need to include blowfish.h in the mex statement

 

[klun]

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Code C - [expand]
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#include "stdafx.h"
#include "blowfish.h"
 
#define N               16/* Exchange Xl and Xr */
        temp = Xl;
        Xl = Xr;
        Xr = temp;
    }
 
    /* Exchange Xl and Xr */
    temp = Xl;
    Xl = Xr;
    Xr = temp;
 
    Xr = Xr ^ ctx->P[1];
    Xl = Xl ^ ctx->P[0];
 
    *xl = Xl;
    *xr = Xr;
}
 
 
void Blowfish_Init(BLOWFISH_CTX *ctx, unsigned char *key, int keyLen) {
    int i, j, k;
    unsigned long data, datal, datar;
 
    for (i = 0; i < 4; i++) {
        for (j = 0; j < 256; j++)
            ctx->S[i][j] = ORIG_S[i][j];
    }
 
    j = 0;
    for (i = 0; i < N + 2; ++i) {
        data = 0x00000000;
        for (k = 0; k < 4; ++k) {
            data = (data << 8) | key[j];
            j = j + 1;
            if (j >= keyLen)
                j = 0;
        }
        ctx->P[i] = ORIG_P[i] ^ data;
    }
 
    datal = 0x00000000;
    datar = 0x00000000;
 
    for (i = 0; i < N + 2; i += 2) {
        Blowfish_Encrypt(ctx, &datal, &datar);
        ctx->P[i] = datal;
        ctx->P[i + 1] = datar;
    }
 
    for (i = 0; i < 4; ++i) {
        for (j = 0; j < 256; j += 2) {
            Blowfish_Encrypt(ctx, &datal, &datar);
            ctx->S[i][j] = datal;
            ctx->S[i][j + 1] = datar;
        }
    }
}
 
 
 
int _tmain(int argc, _TCHAR* argv[])
{
    return 0;
}

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This is my blowfish_koc.cpp file sir. I dont see any difference in the function names and types. And yea, I did included blowfish.h in blowfish_koc.cpp

 

[horace1]

try commenting out

#include "stdafx.h"

in both files

 

[horace1]

make sure you have

#include "mex.h"

in both files

 

[klun]

C code to Matlab code (new to Matlab)

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Code C - [expand]
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#include "blowfish.h"
#include "mex.h"
#include "math.h"
#include "string.h"
#include <stdio.h>
#include <iostream>
#include <sstream>
#include <cstdlib>
 
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
  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 = "";
  
  mxArray *new_number, *str;
  double out;
 
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;*/
  
const char* key = inputkey.c_str();
 
int keylen = strlen(key);
 
char const* plaintext_string = input.c_str();
 
int plaintext_len = strlen(plaintext_string);
Blowfish_Init(&ctx, (unsigned char*)key, keylen);
 
mexPrintf("Encrypted message string is: ");
 
 
while (plaintext_len) 
   {
     message_left = message_right = 0UL;
 
     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;
     }
 
     Blowfish_Encrypt(&ctx, &message_left, &message_right);
     mexPrintf("%lx%lx", message_left, message_right);
    
     *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");
 
mexPrintf("Please enter a valid Decryption key:\n");
 
scanf_s("%s",inputDkey);
 
mexPrintf("Your key:%s",inputDkey);
 
const char* Dkey = inputDkey.c_str();
 
int Dkeylen = strlen(Dkey);
Blowfish_Init(&ctx, (unsigned char*)Dkey, keylen);
 
     printf("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);
 
        printf("%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\n");
   }

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Can anyone here willing to spend some time in helping me to convert this C code to Matlab code? I have trouble with the syntax of Matlab as I am new to Matlab. Thanks for your help. Much appreciated!