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fockingServer.c
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/
fockingServer.c
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#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
long int p =13,q =17,n,t,flag,e[1000],d[1000],temp[1000],j,en[1000],m[1000],i;
char buff[1000];
int prime(long int);
void ce();
long int cd(long int);
void encrypt();
void decrypt();
void sig_chld(int signo)
{
pid_t pid;
int stat;
while((pid = waitpid(-1, &stat, WNOHANG))>0)
printf("child %d terminated\n", pid);
return;
}
int main()
{
int listen_sock, conn_sock;
int server_len, client_len;
struct sockaddr_in server_address;
struct sockaddr_in client_address;
listen_sock = socket(AF_INET, SOCK_STREAM, 0);
if (listen_sock == -1)
{
printf("khong tao duoc socket\n");
return 0;
}
printf("Tao socket thanh cong\n");
server_address.sin_family = AF_INET;
inet_aton("127.0.0.1",&server_address.sin_addr);
server_address.sin_port = htons(5500);
server_len = sizeof(server_address);
if(bind(listen_sock, (struct sockaddr *)&server_address,server_len)<0)
{
printf("bind failed.\n");
return 0;
}
printf("bind done\n");
int check = listen(listen_sock,10);
if (check == -1)
{
printf("error connect");
return 0;
}
printf("waiting connect ...\n");
while(1) {
client_len = sizeof(client_address);
conn_sock = accept(listen_sock,(struct sockaddr *)&client_address, &client_len);
if(conn_sock==-1){
printf("error connect\n");
return 1;
}else{
printf("Accept new connection\n");
}
if(fork() == 0){
close(listen_sock);
int sentBytes,revedBytes,i;
//char buff[1024];
int chose;
while(1){
revedBytes = recv(conn_sock,buff,1024,0);
if(revedBytes < 0) break;
if(strcmp(buff,"S")==0) chose = 1;
else if(strcmp(buff,"M")==0) chose =2;
else if(strcmp(buff,"exit")==0) chose = 3;
switch(chose){
case 1:
printf("Menu1 \n");
while(1){
revedBytes = recv(conn_sock,buff,1024,0);
buff[revedBytes]='\0';
if(strcmp(buff,"Q")==0) break;
printf("string send by client : %s\n",buff);
for(i=0;buff[i]!=NULL;i++)
m[i]=buff[i];
n=p*q;
t=(p-1)*(q-1);
ce();
encrypt();
//decrypt();
for (i = 0; i < strlen(buff); i++)
{
buff[i]=en[i];
}
sentBytes=send(conn_sock,buff,1024,0);
}
printf("exit menu1 \n");
break;
case 2:
printf("\n Menu2");
while(1){
revedBytes = recv(conn_sock,buff,1024,0);
buff[revedBytes]='\0';
if(strcmp(buff,"Q")==0) break;
printf("string send by client : %s\n",buff);
n=p*q;
t=(p-1)*(q-1);
for(i=0;buff[i]!=NULL;i++)
en[i]=buff[i] ;
ce();decrypt();
for (i = 0; m[i]!=-1; i++)
{
buff[i]=(char)m[i];
}
buff[i]='\0';
printf("%s\n",buff);
sentBytes=send(conn_sock,buff,1024,0);
}
printf("exit menu2 \n");
break;
case 3:
close(conn_sock);
break;
default:
break;
}
}
close(conn_sock);
exit(1);
}
signal(SIGCHLD,sig_chld);
}
return 1;
}
int prime(long int pr)
{
int i;
j=sqrt(pr);
for(i=2;i<=j;i++)
{
if(pr%i==0)
return 0;
}
return 1;
}
void ce()
{
int k;
k=0;
for(i=2;i<t;i++)
{
if(t%i==0)
continue;
flag=prime(i);
if(flag==1&&i!=p&&i!=q)
{
e[k]=i;
flag=cd(e[k]);
if(flag>0)
{
d[k]=flag;
k++;
}
if(k==99)
break;
}
}
}
long int cd(long int x)
{
long int k=1;
while(1)
{
k=k+t;
if(k%x==0)
return(k/x);
}
}
void encrypt()
{
long int pt,ct,key=e[0],k,len;
i=0;
len=strlen(buff);
while(i!=len)
{
pt=m[i];
pt=pt-96;
k=1;
for(j=0;j<key;j++)
{
k=k*pt;
k=k%n;
}
temp[i]=k;
ct=k+96;
en[i]=ct;
i++;
}
en[i]=-1;
printf("\nTHE ENCRYPTED MESSAGE IS\n");
printf("%s\n",en );
for(i=0;en[i]!=NULL;i++)
printf("%c",en[i]);
}
void decrypt()
{
long int pt,ct,key=d[0],k;
i=0;
while(en[i]!=0)
{
ct=temp[i];
k=1;
for(j=0;j<key;j++)
{
k=k*ct;
k=k%n;
}
pt=k+96;
m[i]=pt;
i++;
}
m[i]=-1;
printf("\nTHE DECRYPTED MESSAGE IS\n");
for(i=0;m[i]!=NULL;i++)
printf("%c",m[i]);
}