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_);