Columnar transposition algorithm

perform encryption and decryption using Columnar transposition algorithm

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Write a program to perform encryption and decryption using Columnar transposition algorithm.

CODE:

#include<stdio.h>
#include<string.h>
void cipher(int i,int c);
int findMin();
void makeArray(int,int);
char arr[22][22],darr[22][22],emessage[111],retmessage[111],key[55];
char temp[55],temp2[55];
int k=0;
int main() {
char *message,*dmessage;
int i,j,klen,emlen,flag=0;
int r,c,index,min,rows;
clrscr();
printf("Enetr the key\n");
fflush(stdin);
gets(key);
printf("\nEnter message to be ciphered\n");
fflush(stdin);
gets(message);
strcpy(temp,key);
klen=strlen(key);
k=0;
for (i=0; ;i++) {
if(flag==1)
break;
for (j=0;key[j]!=NULL;j++) {
if(message[k]==NULL) {
flag=1;
arr[i][j]='-';
} else {
arr[i][j]=message[k++];
}
}
}
r=i;
c=j;
for (i=0;i<r;i++) {
for (j=0;j<c;j++) {
printf("%c ",arr[i][j]);
}
printf("\n");
}
k=0;
for (i=0;i<klen;i++) {

index=findMin();
cipher(index,r);
}
emessage[k]='\0';
printf("\nEncrypted message is\n");
for (i=0;emessage[i]!=NULL;i++)
printf("%c",emessage[i]);
printf("\n\n");
emlen=strlen(emessage);
strcpy(temp,key);
rows=emlen/klen;
rows;
j=0;
for (i=0,k=1;emessage[i]!=NULL;i++,k++) {
temp2[j++]=emessage[i];
if((k%rows)==0) {
temp2[j]='\0';
index=findMin();
makeArray(index,rows);
j=0;
}
}
printf("\nArray Retrieved is\n");
k=0;
for (i=0;i<r;i++) {
for (j=0;j<c;j++) {
printf("%c ",darr[i][j]);
retmessage[k++]=darr[i][j];
}
printf("\n");
}
retmessage[k]='\0';
printf("\nMessage retrieved is\n");
for (i=0;retmessage[i]!=NULL;i++)
printf("%c",retmessage[i]);
getch();
return(0);
}
void cipher(int i,int r) {
int j;
for (j=0;j<r;j++) { {
emessage[k++]=arr[j][i];
}
}
}
void makeArray(int col,int row) {

int i,j;
for (i=0;i<row;i++) {
darr[i][col]=temp2[i];
}
}
int findMin() {
int i,j,min,index;
min=temp[0];
index=0;
for (j=0;temp[j]!=NULL;j++) {
if(temp[j]<min) {
min=temp[j];
index=j;
}
}
temp[index]=123;
return(index);
}

OUTPUT