Implement CRC (Cyclic Redundancy Code)

#include<stdio.h>
#include <string.h>
void main()
{
int i,j,keylen,msglen;
char input[100], key[30],temp[30],quot[100],rem[30],key1[30];

printf("Enter Data: ");
gets(input);
printf("Enter Key: ");
gets(key);
keylen=strlen(key);
msglen=strlen(input);
strcpy(key1,key);
for(i=0;i<keylen-1;i++)
{
input[msglen+i]='0';
}
for(i=0;i<keylen;i++)
temp[i]=input[i];
for(i=0;i<msglen;i++)
{
quot[i]=temp[0];
if(quot[i]=='0')
for(j=0;j<keylen;j++)
key[j]='0';
else
for(j=0;j<keylen;j++)
key[j]=key1[j];
for(j=keylen-1;j>0;j--)
{
if(temp[j]==key[j])
rem[j-1]='0';
else
rem[j-1]='1';
}
rem[keylen-1]=input[i+keylen];
strcpy(temp,rem);
}
strcpy(rem,temp);
printf("\nQuotient is ");
for(i=0;i<msglen;i++)
printf("%c",quot[i]);
printf("\nRemainder is ");
for(i=0;i<keylen-1;i++)
printf("%c",rem[i]);
printf("\nFinal data is: ");
for(i=0;i<msglen;i++)
printf("%c",input[i]);
for(i=0;i<keylen-1;i++)
printf("%c",rem[i]);
}

OUTPUT:

Enter Data: 11110110101
Enter Key: 111010

Quotient is 10010010000
Remainder is 00000
Final data is: 1111011010100000