static int mod_decrypt(hcrypt_plaintext_t *pt, const hcrypt_ciphertext_t *ct,
hcrypt_prvkey_t *sk)
{
OPENSSL_assert(pt && ct && sk);
OPENSSL_assert(pt->algor == hcrypt_elgamal());
OPENSSL_assert(ct->algor == hcrypt_elgamal());
OPENSSL_assert(sk->algor == hcrypt_elgamal());
OPENSSL_assert(pt->u.elgamal);
OPENSSL_assert(ct->u.elgamal);
OPENSSL_assert(sk->u.elgamal);
if (elgamal_decrypt(pt->u.elgamal, ct->u.elgamal, sk->u.elgamal) < 0) {
fprintf(stderr, "decrypt failed\n");
return -1;
}
return 0;
}
int main(void)
{
int listenfd = 0, connfd = 0, i = 0, m_len, ack;
struct sockaddr_in serv_addr;
int sendBuff[mx_l], recvBuff[mx_l], message[mx_l];
char str[mx_l], dummy;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
system("clear");
printf("Server Initialized\n");
printf("1. Put server on auto reply\n2. Put server on custom reply mode\n");
scanf("%d",&ack);
dummy=getchar();
memset(&serv_addr, '0', sizeof(serv_addr));
memset(sendBuff, '0', sizeof(sendBuff));
memset(recvBuff, '0', sizeof(recvBuff));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(port);
bind(listenfd, (struct sockaddr*)&serv_addr,sizeof(serv_addr));
if(listen(listenfd, 10) == -1) {
printf("Failed to listen\n");
return -1;
}
init_keys(); // Initialize crypto keys
while(1) {
connfd = accept(listenfd, (struct sockaddr*)NULL ,NULL); // accept awaiting request
puts("Connection with Client established\n");
write(connfd, &pub_key, sizeof(pub_key));
write(connfd, &ser_pub_key, sizeof(ser_pub_key));
read(connfd, &cli_pub_key, sizeof(cli_pub_key));
printf("pubic key = %d\n", pub_key);
printf("Server public key = %d\n", ser_pub_key);
printf("Client public key = %d\n", cli_pub_key);
while(read(connfd, recvBuff, sizeof(recvBuff)-1)) {
m_len=0;
for (i=0;i<recvBuff[i]!=0;i++) {
m_len++;
}
printf("\nMessage from client- (Encrypted message): \n");
elgamal_decrypt(recvBuff, message, m_len, cli_pub_key, ser_pri_key);
printf("Decrypted message from client: ");
disp(message, m_len);
if (ack==1) {
strcpy(str, "Message recieved successfully");
}
else if (ack==2) {
printf("Reply to client: ");
gets(str);
}
write(connfd, str, sizeof(str)-1);
}
}
return 0;
}