diff --git a/src/curve_client.cpp b/src/curve_client.cpp
index fae7414d..e0641990 100644
--- a/src/curve_client.cpp
+++ b/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;
diff --git a/src/curve_client.hpp b/src/curve_client.hpp
index 254d94f0..66a071ff 100644
--- a/src/curve_client.hpp
+++ b/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:
diff --git a/src/curve_server.cpp b/src/curve_server.cpp
index 87e56706..708694de 100644
--- a/src/curve_server.cpp
+++ b/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) {
diff --git a/src/curve_server.hpp b/src/curve_server.hpp
index 2d6b6cd0..1eafc3c7 100644
--- a/src/curve_server.hpp
+++ b/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;
 
diff --git a/src/mechanism.hpp b/src/mechanism.hpp
index a9b04172..a1127f30 100644
--- a/src/mechanism.hpp
+++ b/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; }
 
diff --git a/src/stream_engine.cpp b/src/stream_engine.cpp
index 16404e05..0df3ac0a 100644
--- a/src/stream_engine.cpp
+++ b/src/stream_engine.cpp
@@ -42,6 +42,8 @@
 #include "v2_decoder.hpp"
 #include "null_mechanism.hpp"
 #include "plain_mechanism.hpp"
+#include "curve_client.hpp"
+#include "curve_server.hpp"
 #include "raw_decoder.hpp"
 #include "raw_encoder.hpp"
 #include "config.hpp"
@@ -459,10 +461,18 @@ bool zmq::stream_engine_t::handshake ()
                 else {
                     outpos [outsize++] = 0; //  Minor version number
                     memset (outpos + outsize, 0, 20);
+
+                    zmq_assert (options.mechanism == ZMQ_NULL
+                            ||  options.mechanism == ZMQ_PLAIN
+                            ||  options.mechanism == ZMQ_CURVE);
+
                     if (options.mechanism == ZMQ_NULL)
                         memcpy (outpos + outsize, "NULL", 4);
                     else
+                    if (options.mechanism == ZMQ_PLAIN)
                         memcpy (outpos + outsize, "PLAIN", 5);
+                    else
+                        memcpy (outpos + outsize, "CURVE", 5);
                     outsize += 20;
                     memset (outpos + outsize, 0, 32);
                     outsize += 32;
@@ -539,6 +549,16 @@ bool zmq::stream_engine_t::handshake ()
             mechanism = new (std::nothrow) plain_mechanism_t (session, options);
             alloc_assert (mechanism);
         }
+#ifdef HAVE_LIBSODIUM
+        else
+        if (memcmp (greeting_recv + 12, "CURVE\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 20) == 0) {
+            if (options.as_server)
+                mechanism = new (std::nothrow) curve_server_t (session, options);
+            else
+                mechanism = new (std::nothrow) curve_client_t (options);
+            alloc_assert (mechanism);
+        }
+#endif
         else {
             error ();
             return false;
@@ -643,8 +663,8 @@ void zmq::stream_engine_t::mechanism_ready ()
         errno_assert (rc == 0);
     }
 
-    read_msg = &stream_engine_t::pull_msg_from_session;
-    write_msg = &stream_engine_t::push_msg_to_session;
+    read_msg = &stream_engine_t::pull_and_encode;
+    write_msg = &stream_engine_t::decode_and_push;
 }
 
 int zmq::stream_engine_t::pull_msg_from_session (msg_t *msg_)
@@ -657,6 +677,39 @@ int zmq::stream_engine_t::push_msg_to_session (msg_t *msg_)
     return session->push_msg (msg_);
 }
 
+int zmq::stream_engine_t::pull_and_encode (msg_t *msg_)
+{
+    zmq_assert (mechanism != NULL);
+
+    if (session->pull_msg (msg_) == -1)
+        return -1;
+    if (mechanism->encode (msg_) == -1)
+        return -1;
+    return 0;
+}
+
+int zmq::stream_engine_t::decode_and_push (msg_t *msg_)
+{
+    zmq_assert (mechanism != NULL);
+
+    if (mechanism->decode (msg_) == -1)
+        return -1;
+    if (session->push_msg (msg_) == -1) {
+        if (errno == EAGAIN)
+            write_msg = &stream_engine_t::push_one_then_decode_and_push;
+        return -1;
+    }
+    return 0;
+}
+
+int zmq::stream_engine_t::push_one_then_decode_and_push (msg_t *msg_)
+{
+    const int rc = session->push_msg (msg_);
+    if (rc == 0)
+        write_msg = &stream_engine_t::decode_and_push;
+    return rc;
+}
+
 int zmq::stream_engine_t::write_subscription_msg (msg_t *msg_)
 {
     msg_t subscription;
diff --git a/src/stream_engine.hpp b/src/stream_engine.hpp
index 1f337e02..d4d36b1e 100644
--- a/src/stream_engine.hpp
+++ b/src/stream_engine.hpp
@@ -102,6 +102,10 @@ namespace zmq
         int pull_msg_from_session (msg_t *msg_);
         int push_msg_to_session (msg_t *msg);
 
+        int pull_and_encode (msg_t *msg_);
+        int decode_and_push (msg_t *msg_);
+        int push_one_then_decode_and_push (msg_t *msg_);
+
         void mechanism_ready ();
 
         int write_subscription_msg (msg_t *msg_);