I have the Client Server ( 2 separate programs in C, a client process and a server process. The

client process makes a connection to the server, and transmits a RSA encoded message to the server. The

server listens for client communication and when it has received the message, it decodes it and displays the

message on the screeN) codes in C, but need to add the following to it:

TO DO : >break up longer strings into 10 char blocks, encode, transmit, and recombine multiple blocks

on the server side. Note: you should transmit the number of blocks to the server before sending.

The code is listed below for both Client and server:

CLIENT CODE

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

void error(char *msg)

{

perror(msg);

exit(0);

}

int main(int argc, char *argv[])

{

int sockfd, portno, n;

mpz_t rsn, rse, pt, ct;

struct sockaddr_in serv_addr;

struct hostent *server;

char buffer[256], psbuffer[256];

if (argc < 3) {

fprintf(stderr,"usage %s hostname port ", argv[0]);

exit(0);

}

portno = atoi(argv[2]);

sockfd = socket(AF_INET, SOCK_STREAM, 0);

if (sockfd < 0)

error("ERROR opening socket");

server = gethostbyname(argv[1]);

if (server == NULL) {

fprintf(stderr,"ERROR, no such host ");

exit(0);

}

bzero((char *) &serv_addr, sizeof(serv_addr));

serv_addr.sin_family = AF_INET;

bcopy((char *)server->h_addr,

(char *)&serv_addr.sin_addr.s_addr,

server->h_length);

serv_addr.sin_port = htons(portno);

if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)

error("ERROR connecting");

printf("Please enter the message: ");

bzero(buffer,256);

fgets(buffer,255,stdin);

mpz_init(pt);

mpz_init(ct);

mpz_init_set_str(rsn, "9516311845790656153499716760847001433441357", 10);

mpz_init_set_str(rse, "65537", 10);

mpz_import(pt, strlen(buffer), 1, 1, 0, 0, buffer);

if (mpz_cmp(pt, rsn) > 0)

abort();

mpz_powm(ct, pt, rse, rsn);

mpz_get_str(psbuffer,10,ct);

gmp_printf("Encoded: %Zd ", ct);

n = write(sockfd,psbuffer,strlen(psbuffer));

if (n < 0)

error("ERROR writing to socket");

bzero(buffer,256);

n = read(sockfd,buffer,255);

if (n < 0)

error("ERROR reading from socket");

printf("%s ",buffer);

close(sockfd);

return 0;

}//end client

SERVER CODE

#include

#include

#include

#include

#include

#include

#include

#include

#include

void error(char *msg)

{

perror(msg);

exit(1);

}

int main(int argc, char *argv[])

{

int sockfd, newsockfd, portno, clilen;

mpz_t rsn, rsd, pt, ct;

char buffer[256], psbuffer[256];

struct sockaddr_in serv_addr, cli_addr;

int n;

if (argc < 2) {

fprintf(stderr,"ERROR, no port provided ");

exit(1);

}

sockfd = socket(AF_INET, SOCK_STREAM, 0);

if (sockfd < 0)

error("ERROR opening socket");

bzero((char *) &serv_addr, sizeof(serv_addr));

portno = atoi(argv[1]);

serv_addr.sin_family = AF_INET;

serv_addr.sin_addr.s_addr = INADDR_ANY;

serv_addr.sin_port = htons(portno);

if (bind(sockfd, (struct sockaddr *) &serv_addr,

sizeof(serv_addr)) < 0)

error("ERROR on binding");

listen(sockfd,5);

clilen = sizeof(cli_addr);

newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);

if (newsockfd < 0)

error("ERROR on accept");

bzero(buffer,256);

n = read(newsockfd,buffer,255);

if (n < 0) error("ERROR reading from socket");

mpz_init(pt);

mpz_init(ct);

mpz_init_set_str(rsn, "9516311845790656153499716760847001433441357", 10);

mpz_init_set_str(rsd, "5617843187844953170308463622230283376298685", 10);

mpz_set_str(ct, buffer, 10);

gmp_printf("Encoded: %Zd ", ct);

mpz_powm(pt, ct, rsd, rsn);

gmp_printf("Decoded: %Zd ", pt);

mpz_export(psbuffer, NULL, 1, 1, 0, 0, pt);

printf("Here is the message: %s ",psbuffer);

n = write(newsockfd,"I got your message",18);

if (n < 0) error("ERROR writing to socket");

close(newsockfd);

close(sockfd);

return 0;

}//close server

FOR TESTING ENTER:

Please enter the message: Hi there C424!

Encoded: 7114878424839051301866301460808272575931334

I got your message

Encoded: 7114878424839051301866301460808272575931334

Decoded: 375977598150559964853954922339901706

As String: Hi there C424!