encrypt

main.cpp

@@ -15,6 +15,18 @@
 
 in_addr_t remote;
 
+auto cipher = "Mathematics is the art of giving the same name to different things";
+
+void encrypt(char *buffer, size_t length) {
+    for (auto i = 0; i < length; i++) {
+        buffer[i] ^= cipher[i];
+    }
+}
+
+void decrypt(char *buffer, size_t length) {
+    encrypt(buffer, length);
+}
+
 // internet -> tun
 void inbound(int raw, int tun) {
     char buf[ETH_DATA_LEN];
@@ -25,7 +37,10 @@ void inbound(int raw, int tun) {
 //        std::cout << "received " << packet_length << " bytes from " << inet_ntoa(address.sin_addr) << std::endl;
         auto *packet = (iphdr *) buf;
         auto overhead = packet->ihl * 4;
-        if (write(tun, buf + overhead, packet_length - overhead) < 0) {
+        auto payload = buf + overhead;
+        auto payload_length = packet_length - overhead;
+        decrypt(payload, payload_length);
+        if (write(tun, payload, payload_length) < 0) {
             perror("inbound write");
         }
     }
@@ -39,6 +54,7 @@ void outbound(int raw, int tun) {
     address.sin_addr.s_addr = remote;
     size_t packet_length;
     while ((packet_length = read(tun, buf, sizeof(buf))) >= 0) {
+        encrypt(buf, packet_length);
         if (sendto(raw, buf, packet_length, 0, (sockaddr *) &address, sizeof(address)) < 0) {
             perror("outbound write");
         }
@@ -46,6 +62,7 @@ void outbound(int raw, int tun) {
     perror("outbound read");
 }
 
+
 namespace po = boost::program_options;
 
 int main(int argc, char *argv[]) {