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client.c (3684B)
1 #! /usr/bin/env sheepy
2
3 /*
4 client and server are following request/response model.
5
6 Steps in client
7 - generate keys
8 - connect to server
9 - send public key
10 - store remote public key
11 - send encrypted message
12 - get encrypted response
13
14 Steps in server
15 - generate keys
16 - start event loop
17 - store remote public key
18 - send public key
19 - get encrypted message
20 - send encrypted response
21
22 It uses public key encryption which is slow compare to secret/symetric key encryption
23 Secret key encryption is between 25 and 50 times faster than public key encryption depending on the CPU.
24 With secret key encryption, my computer can encode 4GB/s which is enough (I have 1GB/s network).
25
26 The client and server don't have identities, the client can't verify the server and the server can't verify the client
27
28 The nonces are not verified, each nonce can be used multiple times, so replay attacks would be successful.
29 */
30
31 #include "libsheepyObject.h"
32
33 #include <sys/types.h>
34 #include <sys/socket.h>
35 #include <netdb.h>
36 #include <netinet/in.h>
37
38 #include "sel.h"
39
40 int main(int ac, char **av) {
41
42 setLogMode(LOG_FUNC);
43
44 if (not selInit()) ret 1;
45
46 // generate keys
47 keyst clientKeys = init0Var;
48
49 newKeys(&clientKeys);
50
51 char *msg = "Hello";
52
53 logI("message: %s\n", msg);
54
55
56 // connect to server
57 int sock;
58 struct sockaddr_in server;
59 struct hostent *hp;
60 int mysock;
61 char buf[128*1024];
62 int rval;
63
64 sock = socket(AF_INET, SOCK_STREAM, 0);
65 if (sock < 0){
66 perror("Failed to create socket");
67 }
68
69 server.sin_family = AF_INET;
70
71 hp = gethostbyname(av[1]);
72 if (hp==0) {
73 perror("gethostbyname failed");
74 close(sock);
75 exit(1);
76 }
77
78 memcpy(&server.sin_addr, hp->h_addr, hp->h_length);
79 server.sin_port = htons(5000);
80
81 if (connect(sock,(struct sockaddr *) &server, sizeof(server))){
82 perror("connect failed");
83 close(sock);
84 exit(1);
85 }
86
87 void snd(void *buf, size_t sz) {
88 logVarG(sz);
89 if(send(sock, buf, sz, 0) < 0){
90 perror("send failed");
91 close(sock);
92 exit(1);
93 }
94 }
95
96 void rcv(void *buf, size_t sz) {
97 rval = recv(sock, buf, sizeof(buf), 0);
98 if (rval < 0) {
99 perror("reading message");
100 exit(1);
101 }
102 else if (rval == 0) {
103 logI("Ending connection");
104 close(sock);
105 exit(0);
106 }
107 logVarG(rval);
108 }
109
110 // send public key
111 // store remote public key
112 void getServerPublicKey(void) {
113 snd(&clientKeys.publicKey, sizeof(clientKeys.publicKey));
114 rval = recv(sock, &clientKeys.remotePublicKey, sizeof(clientKeys.remotePublicKey), MSG_WAITALL);
115 if (rval < 0) {
116 perror("reading message");
117 exit(1);
118 }
119 else if (rval == 0) {
120 logI("Ending connection");
121 close(sock);
122 exit(0);
123 }
124 logVarG(rval);
125
126 logD("Remote public key");
127 loghex(clientKeys.remotePublicKey, sizeof(clientKeys.remotePublicKey));
128 put;
129 }
130
131 getServerPublicKey();
132
133 // send encrypted message
134 //randombytes_buf(clientKeys.nonce, sizeof(clientKeys.nonce));
135 int len = selPublicEncrypt(buf, sizeof(buf), msg, strlen(msg), &clientKeys);
136
137 logVarG(len);
138
139 snd(&len, sizeof(len));
140 snd(buf, len);
141
142 // get encrypted response
143 rcv(&len, sizeof(len));
144 rval = recv(sock, buf, len, MSG_WAITALL);
145 if (rval < 0) {
146 perror("reading message");
147 exit(1);
148 }
149 else if (rval == 0) {
150 logI("Ending connection");
151 close(sock);
152 exit(0);
153 }
154 logVarG(rval);
155
156 clientKeys.nonce[0] = 1;
157
158 u8 decrypted[1000];
159 len = selPublicDecrypt(decrypted, sizeof(decrypted), buf, rval, &clientKeys);
160
161 if (!len) {
162 logE("failed to decrypt");
163 ret 1;
164 }
165
166 decrypted[len] = 0;
167
168 logI("decrypted: %s", decrypted);
169
170 close(sock);
171 }
172 // vim: set expandtab ts=2 sw=2: