C Source file of program
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<string.h>
void main()
{
char plain[200],encr[200],encr1[200],decr[200];
int ch,flag[26];
char ch1;
char per[26];
int i,j,size,k=0,a=0;
char pos;
clrscr();
printf("\nEnter the plain text");
gets(plain);
size=strlen(plain);
printf("\n size= %d",size);
for(i=0;i<26;i++)
flag[i]=0;
for(i=0;i<26;i++)
{
a=rand()%26;
while(flag[a]==1)
a=rand()%26;
flag[a]=1;
per[i]=(char)(a+97);
}
printf("\nPermuted array is: ");
for(i=0;i<26;i++)
{
printf("%c ",per[i]);
}
for(j=0;j<size;j++)
{
ch=plain[j];
ch=ch-97;
ch1=per[ch];
encr1[j]=ch1;
}
//encr1[25]='\0';
printf("\nthe encrypted string is ");
for(i=0;i<size;i++)
{
printf("%c",encr1[i]);
}
//decryption
i=0;
while(i<size)
{
//a=ct[i];
//a=a-97;
//pt[i]=key[a];
a=0;
while(a!=26)
{
if(per[a]==encr1[i])
{
decr[i]=a+97;
break;
}
a++;
}
i++;
}
decr[i]='\0';
printf("\nDecrypted string: %s\n",decr);
getch();
}
Output :
