Implement CurveZMQ message encryption and authentication

src/curve_client.cpp

@@ -101,6 +101,113 @@ int zmq::curve_client_t::process_handshake_message (msg_t *msg_)
     return rc;
 }
 
+int zmq::curve_client_t::encode (msg_t *msg_)
+{
+    zmq_assert (state == connected);
+
+    uint8_t flags = 0;
+    if (msg_->flags () & msg_t::more)
+        flags |= 0x01;
+
+    uint8_t message_nonce [crypto_box_NONCEBYTES];
+    memcpy (message_nonce, "CurveZMQMESSAGEC", 16);
+    memcpy (message_nonce + 16, &cn_nonce, 8);
+
+    const size_t mlen = crypto_box_ZEROBYTES + 1 + msg_->size ();
+
+    uint8_t *message_plaintext = static_cast <uint8_t *> (malloc (mlen));
+    alloc_assert (message_plaintext);
+
+    memset (message_plaintext, 0, crypto_box_ZEROBYTES);
+    message_plaintext [crypto_box_ZEROBYTES] = flags;
+    memcpy (message_plaintext + crypto_box_ZEROBYTES + 1,
+            msg_->data (), msg_->size ());
+
+    uint8_t *message_box = static_cast <uint8_t *> (malloc (mlen));
+    alloc_assert (message_box);
+
+    int rc = crypto_box_afternm (message_box, message_plaintext,
+                                 mlen, message_nonce, cn_precom);
+    zmq_assert (rc == 0);
+
+    rc = msg_->close ();
+    zmq_assert (rc == 0);
+
+    rc = msg_->init_size (16 + mlen - crypto_box_BOXZEROBYTES);
+    zmq_assert (rc == 0);
+
+    uint8_t *message = static_cast <uint8_t *> (msg_->data ());
+
+    memcpy (message, "MESSAGE ", 8);
+    memcpy (message + 8, &cn_nonce, 8);
+    memcpy (message + 16, message_box + crypto_box_BOXZEROBYTES,
+            mlen - crypto_box_BOXZEROBYTES);
+
+    free (message_plaintext);
+    free (message_box);
+
+    cn_nonce++;
+
+    return 0;
+}
+
+int zmq::curve_client_t::decode (msg_t *msg_)
+{
+    zmq_assert (state == connected);
+
+    if (msg_->size () < 33) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    const uint8_t *message = static_cast <uint8_t *> (msg_->data ());
+    if (memcmp (message, "MESSAGE ", 8)) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    uint8_t message_nonce [crypto_box_NONCEBYTES];
+    memcpy (message_nonce, "CurveZMQMESSAGES", 16);
+    memcpy (message_nonce + 16, message + 8, 8);
+
+    const size_t clen = crypto_box_BOXZEROBYTES + (msg_->size () - 16);
+
+    uint8_t *message_plaintext = static_cast <uint8_t *> (malloc (clen));
+    alloc_assert (message_plaintext);
+
+    uint8_t *message_box = static_cast <uint8_t *> (malloc (clen));
+    alloc_assert (message_box);
+
+    memset (message_box, 0, crypto_box_BOXZEROBYTES);
+    memcpy (message_box + crypto_box_BOXZEROBYTES,
+            message + 16, msg_->size () - 16);
+
+    int rc = crypto_box_open_afternm (message_plaintext, message_box,
+                                      clen, message_nonce, cn_precom);
+    if (rc == 0) {
+        rc = msg_->close ();
+        zmq_assert (rc == 0);
+
+        rc = msg_->init_size (clen - 1 - crypto_box_ZEROBYTES);
+        zmq_assert (rc == 0);
+
+        const uint8_t flags = message_plaintext [crypto_box_ZEROBYTES];
+        if (flags & 0x01)
+            msg_->set_flags (msg_t::more);
+
+        memcpy (msg_->data (),
+                message_plaintext + crypto_box_ZEROBYTES + 1,
+                msg_->size ());
+    }
+    else
+        errno = EPROTO;
+
+    free (message_plaintext);
+    free (message_box);
+
+    return rc;
+}
+
 bool zmq::curve_client_t::is_handshake_complete () const
 {
     return state == connected;

src/curve_client.hpp

@@ -52,6 +52,8 @@ namespace zmq
         // mechanism implementation
         virtual int next_handshake_message (msg_t *msg_);
         virtual int process_handshake_message (msg_t *msg_);
+        virtual int encode (msg_t *msg_);
+        virtual int decode (msg_t *msg_);
         virtual bool is_handshake_complete () const;
 
     private:

src/curve_server.cpp

@@ -111,6 +111,113 @@ int zmq::curve_server_t::process_handshake_message (msg_t *msg_)
     return rc;
 }
 
+int zmq::curve_server_t::encode (msg_t *msg_)
+{
+    zmq_assert (state == connected);
+
+    const size_t mlen = crypto_box_ZEROBYTES + 1 + msg_->size ();
+
+    uint8_t message_nonce [crypto_box_NONCEBYTES];
+    memcpy (message_nonce, "CurveZMQMESSAGES", 16);
+    memcpy (message_nonce + 16, &cn_nonce, 8);
+
+    uint8_t flags = 0;
+    if (msg_->flags () & msg_t::more)
+        flags |= 0x01;
+
+    uint8_t *message_plaintext = static_cast <uint8_t *> (malloc (mlen));
+    alloc_assert (message_plaintext);
+
+    memset (message_plaintext, 0, crypto_box_ZEROBYTES);
+    message_plaintext [crypto_box_ZEROBYTES] = flags;
+    memcpy (message_plaintext + crypto_box_ZEROBYTES + 1,
+            msg_->data (), msg_->size ());
+
+    uint8_t *message_box = static_cast <uint8_t *> (malloc (mlen));
+    alloc_assert (message_box);
+
+    int rc = crypto_box_afternm (message_box, message_plaintext,
+                                 mlen, message_nonce, cn_precom);
+    zmq_assert (rc == 0);
+
+    rc = msg_->close ();
+    zmq_assert (rc == 0);
+
+    rc = msg_->init_size (16 + mlen - crypto_box_BOXZEROBYTES);
+    zmq_assert (rc == 0);
+
+    uint8_t *message = static_cast <uint8_t *> (msg_->data ());
+
+    memcpy (message, "MESSAGE ", 8);
+    memcpy (message + 8, &cn_nonce, 8);
+    memcpy (message + 16, message_box + crypto_box_BOXZEROBYTES,
+            mlen - crypto_box_BOXZEROBYTES);
+
+    free (message_plaintext);
+    free (message_box);
+
+    cn_nonce++;
+
+    return 0;
+}
+
+int zmq::curve_server_t::decode (msg_t *msg_)
+{
+    zmq_assert (state == connected);
+
+    if (msg_->size () < 33) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    const uint8_t *message = static_cast <uint8_t *> (msg_->data ());
+    if (memcmp (message, "MESSAGE ", 8)) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    uint8_t message_nonce [crypto_box_NONCEBYTES];
+    memcpy (message_nonce, "CurveZMQMESSAGEC", 16);
+    memcpy (message_nonce + 16, message + 8, 8);
+
+    const size_t clen = crypto_box_BOXZEROBYTES + msg_->size () - 16;
+
+    uint8_t *message_plaintext = static_cast <uint8_t *> (malloc (clen));
+    alloc_assert (message_plaintext);
+
+    uint8_t *message_box = static_cast <uint8_t *> (malloc (clen));
+    alloc_assert (message_box);
+
+    memset (message_box, 0, crypto_box_BOXZEROBYTES);
+    memcpy (message_box + crypto_box_BOXZEROBYTES,
+            message + 16, msg_->size () - 16);
+
+    int rc = crypto_box_open_afternm (message_plaintext, message_box,
+                                      clen, message_nonce, cn_precom);
+    if (rc == 0) {
+        rc = msg_->close ();
+        zmq_assert (rc == 0);
+
+        rc = msg_->init_size (clen - 1 - crypto_box_ZEROBYTES);
+        zmq_assert (rc == 0);
+
+        const uint8_t flags = message_plaintext [crypto_box_ZEROBYTES];
+        if (flags & 0x01)
+            msg_->set_flags (msg_t::more);
+
+        memcpy (msg_->data (),
+                message_plaintext + crypto_box_ZEROBYTES + 1,
+                msg_->size ());
+    }
+    else
+        errno = EPROTO;
+
+    free (message_plaintext);
+    free (message_box);
+
+    return rc;
+}
+
 int zmq::curve_server_t::zap_msg_available ()
 {
     if (state != expect_zap_reply) {

src/curve_server.hpp

@@ -56,6 +56,8 @@ namespace zmq
         // mechanism implementation
         virtual int next_handshake_message (msg_t *msg_);
         virtual int process_handshake_message (msg_t *msg_);
+        virtual int encode (msg_t *msg_);
+        virtual int decode (msg_t *msg_);
         virtual int zap_msg_available ();
         virtual bool is_handshake_complete () const;
 

src/mechanism.hpp

@@ -46,6 +46,10 @@ namespace zmq
         //  Process the handshake message received from the peer.
         virtual int process_handshake_message (msg_t *msg_) = 0;
 
+        virtual int encode (msg_t *msg_) { return 0; }
+
+        virtual int decode (msg_t *msg_) { return 0; }
+
         //  Notifies mechanism about availability of ZAP message.
         virtual int zap_msg_available () { return 0; }