- (NSString*)decrypt:(NSString*)encryText modulus:(NSString*)mod exponent:(NSString*)exp
  

  {
  

  

  NSString * hexString = encryText;
  

  int hexStringLength= [hexString length] / 2;
  

  

  //unsigned char enc_bin[144];
  

  unsigned char dec_bin[hexStringLength];
  

  //int enc_len;
  

  int dec_len;
  

  RSA * rsa_pub = RSA_new();
  

  

  

  const char *N=[mod UTF8String] ;
  

  const char *E=[exp UTF8String];
  

  

  

  

  char * myBuffer = (char *)malloc((int)[hexString length] / 2 + 1);
  

  bzero(myBuffer, [hexString length] / 2 + 1);
  

  for (int i = 0; i < [hexString length] - 1; i += 2) {
  

  unsigned int anInt;
  

  NSString * hexCharStr = [hexString substringWithRange:NSMakeRange(i, 2)];
  

  NSScanner * scanner = [[NSScanner alloc] initWithString:hexCharStr];
  

  [scanner scanHexInt:&anInt];
  

  myBuffer[i / 2] = (char)anInt;
  

  }
  

  

  printf("Mybuffer: %s",myBuffer);
  

  

  if (!BN_dec2bn(&rsa_pub->n, N)) {
  

  printf("NO CARGO EL MODULO");
  

  }
  

  printf(" N: %s\n", N);
  

  printf(" n: %s\n", BN_bn2dec(rsa_pub->n));
  

  

  

  if (!BN_dec2bn(&rsa_pub->e, E)) {
  

  printf("NO CARGO EL EXPONENTE");
  

  }
  

  printf(" E: %s\n", E);
  

  printf(" e: %s\n", BN_bn2dec(rsa_pub->e));
  

  

  printf("public key size : %d bits\n", RSA_size(rsa_pub));
  

  NSMutableString *entring = [NSMutableString stringWithCapacity:128];
  

  for (int i = 0; i < hexStringLength; i++) {
  

  [entring appendFormat:@"%x", myBuffer[i]];
  

  }
  

  /* decrypt */
  

  if ((dec_len = RSA_public_decrypt(hexStringLength, (unsigned char*)myBuffer, dec_bin, rsa_pub,RSA_NO_PADDING))<0) {
  

  printf("NO\n ");
  

  }
  

  printf("decrypted data:\n %s", dec_bin);
  

  //    print_hex(dec_bin, dec_len);
  

  

  NSMutableString *decryptString = [[NSMutableString alloc] initWithBytes:dec_bin
  

  length:strlen((char *)dec_bin)
  

  encoding:NSUTF8StringEncoding];
  

  return decryptString;
  

  }