diff --git a/setup.py b/setup.py
index 33f9c401..80fa6cf0 100644
--- a/setup.py
+++ b/setup.py
@@ -100,9 +100,13 @@ extras_require_serialization = [
     "py-ubjson>=0.8.4"          # Apache 2.0 license
 ]
 
-# payload encryption (required for WAMP-cryptosign support!)
+# TLS transport encryption
+# WAMP-cryptosign end-to-end encryption
+# WAMP-cryptosign authentication
 os.environ['SODIUM_INSTALL'] = 'bundled'  # enforce use of bundled libsodium
 extras_require_encryption = [
+    'pyopenssl>=16.2.0',        # Apache 2.0 license
+    'service_identity>=16.0.0', # MIT license
     'pynacl>=1.0.1',            # Apache license
     'pytrie>=0.2',              # BSD license
     'pyqrcode>=1.1'             # BSD license