enc_parallel.c~

imba OS program for all fuctards who use this site

#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

void encrypt(char data,char data1,int key[],int k);/* Function to encrypt a file 2 chars at a time */
void decrypt (int l,int r,int key[]);/*function  to decrypt a file reading encrypted vallue of each char*/
void enc_fie(char filename[],char key[]);/*function which calls the encrypt function*/
void dec_file(char filename[],char key[]);/*function which calls the decrypt function*/
void parallel_enc(char data[],int key[]);

static char a[16];
static char b[16];

int main()

{

  char filename[50];//filename which user enters
  int f1,f2;//file pointers to read from one file in which encrypted data is stored and appending 
            // it in one file for decryption
  char buf1[500];//buffer for reading from enc_temp2 500 chars at a time

  printf("\n enter file to be encrypted \n");
    scanf("%s",filename);

  printf("\n encrypting: %s \n",filename);

  char key[8] = "12345678";

  enc_file(filename,key);//call to encrypt the filename with key 

 

  f1 = open("enc_temp1.txt",O_RDWR |O_APPEND);//opening file descriptor f1 in read write append mode
  f2 = open("enc_temp2.txt",O_RDONLY);

 
  memset(buf1,0,sizeof(buf1));//setting the buffer to 0
  
  while(read(f2,buf1,500)>0)//reading from file enc_temp2
   {
	write(f1,buf1,500);//writing into file enc_temp1
   }


  printf("enter the file you want to decrypt \n");
     scanf("%s",filename);

  dec_file(filename,key);//call to decrypt the file enc_temp1.txt


}
/* ---------------MAIN ENDS------------------*/

/*-----------enc_file STARTS----------------*/
void enc_file(char filename[],char key[])
{
   int fp0;//file pointer 
   int i=0;//for loop
   int key_int[8];//for getting ascii value of the key charadters
   int thread_id;//thread id   

   fp0 = open(filename,O_RDONLY);//opening file for encrption  
   int file_size = (int) (lseek (fp0,0,SEEK_END));//finding the file size
   
   printf("\n File size is: %d \n",file_size);

   int half = file_size / 2;
   close(fp0) ;//closing File Pointer

   for (i=0;i<8;i++)//finding ascii value of key characters
          key_int[i] = (int) key[i];

    omp_set_num_threads(2);//Specifying no of threads
   

  #pragma omp parallel 
  {
       printf("\n---------In parallel region ------------\n");
       
       thread_id = omp_get_thread_num();
       printf("Thread id is : % d \n",thread_id);
 
     if(thread_id==0)
	{
	 int count=0;//counting no of chars read
         char ch,ch1;//characters for reading from file
         FILE *fp1;//file pointer
	
        if ((fp1 = fopen(filename,"r")) == NULL )
	       printf("\n error opening file in Thread 0 \n");

	printf("\n In thread 0 half is:%d \n",half);
	
	
	while(count<half)
		{

		ch1 = getc(fp1);		
		ch = getc(fp1);
		
                printf("\n Encrypting in thread 0 %c and %c \n",ch1,ch);
		
                encrypt(ch1,ch,key_int,thread_id);//calling encrypt to encrypt ch1 and ch
	
		count = count+2;//2 chars encrypted
		}//END OF WHILE
 
	fclose(fp1);//closing fp1
	
	}/* -----------End of Thread 0------------*/

 else if (thread_id==1)
	{
	printf("\n In thread 2 \n");
	
        char ch2,ch3;//characters for reading from the file
	FILE *fp2;
	int position = half;//position to which file pointer needs to be moved
	
       if (((fp2 = fopen(filename,"r")) == NULL));
	          printf("cant open file \n");
	
       /*if (file_size %2 ==0)
  	 position = half;
       else 
	  position = half;*/
	
	if(fseek(fp2,position,SEEK_SET)!=0)//moving file pointer to middle of the file
	      printf("\n lseek failed in Thread 1\n");

       ch2 = getc(fp2);//reading a character

      // printf("char read was : %c \n",ch2);
       
       while(ch2 != EOF)//continue till end of file
		{
		
                ch3 = ch2;
		
		ch2 = getc(fp2);// read 2 character
		printf("\n Encrypting in thread 1 %c and %c \n",ch3,ch2);

		encrypt(ch3,ch2,key_int,thread_id);//encrypt ch3 and ch2
		
                ch2 = getc(fp2);
		}//End of while
	fclose(fp2);//close fp2
	
     }//END oF THREAD 1
}//--------END of PRAGMA ----------------------

 
}//-----------------------END of enc_file-------------------------------------

void dec_file(char filename[], char key[])
{

 FILE *fp1;
 int p,q,i=0;
 int key_int[8];
 fp1 = fopen(filename,"r"); 

 for (i=0;i<8;i++)
   key_int[i] = (int) key[i];

// omp_set_num_threads(8) ;
 
 
 while(fscanf(fp1,"%d %d",&p,&q)>0)//read 2 chars from the file
 {
 
 printf("read from file %d and %d \n",p,q);
 decrypt(p,q,key_int);//calling decrypt
 
 }

 fclose(fp1);//closing fp1

}



void encrypt(char a,char b, int key[],int k1)
{
 int data = (int)a;// getting ascii of 2 chars
 int data2 = (int)b;
 int l[16];//array for finding encrypted value of a and b
 int r[16];

 l[0] = data;
 r[0] = data2;
 int i =0;
 int j=0; 
 int k =0;
 
 for (i=1;i<16;i++)
	{
	if (i>8  && k==0)
          {
		j=0;k++;}

	l[i] = r[i-1] ^ key[j];            
	r[i] = l[i-1] ^ key[j];  
	
        printf("key index :%d \n",j);
	
        printf("l %d is  %d \n",i,l[i]);
	printf("r %d is %d \n ",i,r[i]);
	j++;
	}
  	printf("----------------------------- \n")	; 

	 int buf[2] ={l[15],r[15]};
	 printf("buffer :: %d and %d \n",buf[0],buf[1]); 

	FILE *fp1, *fp2;
	fp1 = fopen("enc_temp1.txt","a");
	fp2 = fopen("enc_temp2.txt","a");

if (k1==0)
{
	printf("\n Now writing enc_temp1.txt \n");
	fprintf(fp1,"%d %d ",l[15],r[15]);
}
else if(k1==1)
{
	printf("\n Now writng enc_temp2.txt \n");
	fprintf(fp2,"%d %d ",l[15],r[15]);
}


fclose(fp1);
fclose(fp2); 
}//----------------------End of encrypt()---------------------------------------------


void decrypt (int l, int r,int key[])
{
 int fp1;
 int p,q;
 fp1 = open("enc.txt",O_WRONLY|O_APPEND);

 int i = 16;
 int k=6;
 int l1[16];
 int r1[16];
 l1[15] = l;
 r1[15] = r;

 for (i=14;i>=0;i--)
	{
	if (k<0)
		k=7;
	l1[i] = r1[i+1] ^  key[k];
	r1[i] = l1[i+1]  ^ key[k];
	k--;
        printf("l %d is  %d \n",i,l1[i]);
        printf("r %d is %d \n ",i,r1[i]);

	}// END of FOR

	char a = (char)(l1[1] ^ key[0]);
	char b = (char)(r1[1]^key[0]);

	printf("char value is %c \n",a);
	printf("char 2 value  is %c \n",b);
	printf("\n******************** \n");
	
	char buf[2];
	buf[1]=a;
	buf[0]=b;

	if (write (fp1,buf,2)==-1)
            printf("write error"); 


	close(fp1);
}//----------------END of decrypt--------------------------------------------