#include <stdio.h>
#include <gcrypt.h>
#include <time.h>
#include <sys/stat.h>
//#define GCRY_CIPHER_AES256
//#define GCRY_KDF_PBKDF2
void intitializeLibrary();

int main(int argc, char **argv)
{
  if(argc ==2){
    char *filename = argv[1];
    printf("The file you've requested to be encrypted is %s \n", filename);
    FILE *ifp, *ifpout;
    char *mode ="rb";

    ifp = fopen(filename, mode);
    ifpout = fopen("output.txt", "w");
    if (ifp == NULL || ifpout == NULL){
      fprintf(stderr, "Can't open file! \n");
      exit(1);
    } else{
      intitializeLibrary();
      struct stat st;
      stat(filename, &st);
      int size = st.st_size;

      char *encBuffer = malloc(32);
      char str[100];
      char keybuffer[32];
      char* salt = "CNT5410";
      char* iv = "assignment222222";
      printf("Enter password: ");
      gcry_cipher_hd_t handle;
      gets(str);

      gpg_error_t err;
      err = gcry_kdf_derive(str, 100, GCRY_KDF_PBKDF2, GCRY_CIPHER_AES256, salt, 7, 3, 32, keybuffer);
      if(err){
	printf("Error in PBKDF2 \n");
	exit(1);
      }

      puts(keybuffer);

      err = gcry_cipher_open(&handle, GCRY_CIPHER_AES256, GCRY_CIPHER_MODE_ECB, 0);
      if(err){
	printf("Error in cipheropen\n");
	exit(1);
      }

      err = gcry_cipher_setkey(handle, keybuffer, 32);
      if(err){
	printf("Error in cipheropen\n");
	exit(1);
      }

      err = gcry_cipher_setiv(handle, iv, 16);
      int bytes;
      while(!feof(ifp)){
	bytes = fread(encBuffer, 1, size, ifp);
	if(!bytes){
	  break;
	}
	while(bytes < 32){
	  encBuffer[bytes++] = 0x0;
	  gcry_cipher_encrypt(handle, encBuffer, size, NULL,0);
	  bytes = fwrite(encBuffer, size, 16, ifpout);
	}
      }

      gcry_cipher_close(handle);
      fclose(ifp);
      fclose(ifpout);

      struct stat st2;
      stat(filename, &st2);
      int size2 = st2.st_size;

      err = gcry_cipher_open(&handle, GCRY_CIPHER_AES256, GCRY_CIPHER_MODE_ECB, 0);
      if(err){
	printf("Error in cipheropen\n");
	exit(1);
      }

      err = gcry_cipher_setkey(handle, keybuffer, 32);
      if(err){
	printf("Error in cipheropen\n");
	exit(1);
      }

      err = gcry_cipher_setiv(handle, iv, 16);
      ifp = fopen("output.txt", mode);
      ifpout = fopen(filename, "w");
      while(!feof(ifp)){
	bytes = fread(encBuffer, 1, size2, ifp);
	if(!bytes){
	  break;
	}
	while(bytes < 32){
	  encBuffer[bytes++] = 0x0;
	  gcry_cipher_encrypt(handle, encBuffer, size2, NULL,0);
	  bytes = fwrite(encBuffer, 1, size2, ifpout);
	}
      }

      free(encBuffer);
      encBuffer = NULL;


    }
  }else{
    puts("Please enter one file to encrypt");
  }
  return 0;
}

void intitializeLibrary(){

  /* Version check should be the very first call because it
     makes sure that important subsystems are intialized. */
  if (!gcry_check_version (GCRYPT_VERSION)){
    fputs ("libgcrypt version mismatch\n", stderr);
    exit (2);
  }

  /* Disable secure memory.  */
  gcry_control (GCRYCTL_DISABLE_SECMEM, 0);

  /* ... If required, other initialization goes here.  */

  /* Tell Libgcrypt that initialization has completed. */
  gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);

  /* Disable secure memory.  */
  gcry_control (GCRYCTL_DISABLE_SECMEM, 0);

  /* ... If required, other initialization goes here.  */

  /* Tell Libgcrypt that initialization has completed. */
  gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);