Add a mode to the echo examples to fix the local ephemeral key

muneebakhter · Apr 23, 2016 · 6eeaa22 · 6eeaa22
1 parent 75dad44
commit 6eeaa22
Show file tree

Hide file tree

Showing 2 changed files with 58 additions and 2 deletions.
diff --git a/examples/echo/echo-client/echo-client.c b/examples/echo/echo-client/echo-client.c
@@ -28,14 +28,15 @@
 #include <unistd.h>
 #include <getopt.h>
 
-#define short_options "c:s:p:gv"
+#define short_options "c:s:p:gvf"
 
 static struct option const long_options[] = {
     {"client-private-key",      required_argument,      NULL,       'c'},
     {"server-public-key",       required_argument,      NULL,       's'},
     {"psk",                     required_argument,      NULL,       'p'},
     {"padding",                 no_argument,            NULL,       'g'},
     {"verbose",                 no_argument,            NULL,       'v'},
+    {"fixed-ephemeral",         no_argument,            NULL,       'f'},
     {NULL,                      0,                      NULL,        0 }
 };
 
@@ -48,11 +49,24 @@ static const char *protocol = NULL;
 static const char *hostname = NULL;
 static int port = 7000;
 static int padding = 0;
+static int fixed_ephemeral = 0;
 
 /* Message buffer for send/receive */
 #define MAX_MESSAGE_LEN 4096
 static uint8_t message[MAX_MESSAGE_LEN + 2];
 
+/* Internal function to directly supply ephemeral keys during testing */
+NoiseDHState *noise_handshakestate_get_fixed_ephemeral_dh_
+    (NoiseHandshakeState *state);
+
+/* Value to use when fixed ephemeral mode is selected */
+static uint8_t const fixed_ephemeral_value[32] = {
+    0x89, 0x3e, 0x28, 0xb9, 0xdc, 0x6c, 0xa8, 0xd6,
+    0x11, 0xab, 0x66, 0x47, 0x54, 0xb8, 0xce, 0xb7,
+    0xba, 0xc5, 0x11, 0x73, 0x49, 0xa4, 0x43, 0x9a,
+    0x6b, 0x05, 0x69, 0xda, 0x97, 0x7c, 0x46, 0x4a
+};
+
 /* Print usage information */
 static void usage(const char *progname)
 {
@@ -68,6 +82,8 @@ static void usage(const char *progname)
     fprintf(stderr, "        Pad messages with random data to a uniform size.\n\n");
     fprintf(stderr, "    --verbose, -v\n");
     fprintf(stderr, "        Print all messages to and from the echo server.\n\n");
+    fprintf(stderr, "    --fixed-ephemeral, -f\n");
+    fprintf(stderr, "        Use a fixed local ephemeral key for testing.\n\n");
 }
 
 /* Parse the command-line options */
@@ -83,6 +99,7 @@ static int parse_options(int argc, char *argv[])
         case 'p':   psk_file = optarg; break;
         case 'g':   padding = 1; break;
         case 'v':   echo_verbose = 1; break;
+        case 'f':   fixed_ephemeral = 1; break;
         default:
             usage(progname);
             return 0;
@@ -168,6 +185,17 @@ static int initialize_handshake
         }
     }
 
+    /* Set the fixed local ephemeral value if necessary */
+    if (fixed_ephemeral) {
+        dh = noise_handshakestate_get_fixed_ephemeral_dh_(handshake);
+        err = noise_dhstate_set_keypair_private
+            (dh, fixed_ephemeral_value, sizeof(fixed_ephemeral_value));
+        if (err != NOISE_ERROR_NONE) {
+            noise_perror("fixed ephemeral value", err);
+            return 0;
+        }
+    }
+
     /* Ready to go */
     return 1;
 }

diff --git a/examples/echo/echo-server/echo-server.c b/examples/echo/echo-server/echo-server.c
@@ -28,17 +28,19 @@
 #include <unistd.h>
 #include <getopt.h>
 
-#define short_options "k:v"
+#define short_options "k:vf"
 
 static struct option const long_options[] = {
     {"key-dir",                 required_argument,      NULL,       'k'},
     {"verbose",                 no_argument,            NULL,       'v'},
+    {"fixed-ephemeral",         no_argument,            NULL,       'f'},
     {NULL,                      0,                      NULL,        0 }
 };
 
 /* Parsed command-line options */
 static const char *key_dir = ".";
 static int port = 7000;
+static int fixed_ephemeral = 0;
 
 /* Loaded keys */
 #define CURVE25519_KEY_LEN 32
@@ -53,6 +55,18 @@ static uint8_t psk[32];
 #define MAX_MESSAGE_LEN 65535
 static uint8_t message[MAX_MESSAGE_LEN + 2];
 
+/* Internal function to directly supply ephemeral keys during testing */
+NoiseDHState *noise_handshakestate_get_fixed_ephemeral_dh_
+    (NoiseHandshakeState *state);
+
+/* Value to use when fixed ephemeral mode is selected */
+static uint8_t const fixed_ephemeral_value[32] = {
+    0xbb, 0xdb, 0x4c, 0xdb, 0xd3, 0x09, 0xf1, 0xa1,
+    0xf2, 0xe1, 0x45, 0x69, 0x67, 0xfe, 0x28, 0x8c,
+    0xad, 0xd6, 0xf7, 0x12, 0xd6, 0x5d, 0xc7, 0xb7,
+    0x79, 0x3d, 0x5e, 0x63, 0xda, 0x6b, 0x37, 0x5b
+};
+
 /* Print usage information */
 static void usage(const char *progname)
 {
@@ -64,6 +78,8 @@ static void usage(const char *progname)
     fprintf(stderr, "        Pre-shared key value to use.\n\n");
     fprintf(stderr, "    --verbose, -v\n");
     fprintf(stderr, "        Print all messages to and from the echo client.\n\n");
+    fprintf(stderr, "    --fixed-ephemeral, -f\n");
+    fprintf(stderr, "        Use a fixed local ephemeral key for testing.\n\n");
 }
 
 /* Parse the command-line options */
@@ -76,6 +92,7 @@ static int parse_options(int argc, char *argv[])
         switch (ch) {
         case 'k':   key_dir = optarg; break;
         case 'v':   echo_verbose = 1; break;
+        case 'f':   fixed_ephemeral = 1; break;
         default:
             usage(progname);
             return 0;
@@ -157,6 +174,17 @@ static int initialize_handshake
         }
     }
 
+    /* Set the fixed local ephemeral value if necessary */
+    if (fixed_ephemeral) {
+        dh = noise_handshakestate_get_fixed_ephemeral_dh_(handshake);
+        err = noise_dhstate_set_keypair_private
+            (dh, fixed_ephemeral_value, sizeof(fixed_ephemeral_value));
+        if (err != NOISE_ERROR_NONE) {
+            noise_perror("fixed ephemeral value", err);
+            return 0;
+        }
+    }
+
     /* Ready to go */
     return 1;
 }