Merge pull request #138 from alkor/fix-password-encryption

Support passwords with SecurityPolicy#None (plain text)

opcua/client/client.py

@@ -381,14 +381,23 @@ class Client(object):
         else:
             params.UserIdentityToken = ua.UserNameIdentityToken()
             params.UserIdentityToken.UserName = username
+            policy_uri = self.server_policy_uri(ua.UserTokenType.UserName)
+            if not policy_uri or policy_uri == security_policies.POLICY_NONE_URI:
+                # see specs part 4, 7.36.3: if the token is NOT encrypted,
+                # then the password only contains UTF-8 encoded password
+                # and EncryptionAlgorithm is null
                 if self.server_url.password:
+                    self.logger.warning("Sending plain-text password")
+                    params.UserIdentityToken.Password = password
+                params.UserIdentityToken.EncryptionAlgorithm = ''
+            elif self.server_url.password:
                 pubkey = uacrypto.x509_from_der(self.security_policy.server_certificate).public_key()
                 # see specs part 4, 7.36.3: if the token is encrypted, password
                 # shall be converted to UTF-8 and serialized with server nonce
                 etoken = ua.pack_bytes(bytes(password, "utf8") + self._server_nonce)
                 (data, uri) = security_policies.encrypt_asymmetric(pubkey,
                         etoken,
-                        self.server_policy_uri(ua.UserTokenType.UserName))
+                        policy_uri)
                 params.UserIdentityToken.Password = data
                 params.UserIdentityToken.EncryptionAlgorithm = uri
             params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.UserName, b"username_basic256")

opcua/crypto/security_policies.py

@@ -9,6 +9,9 @@ except ImportError:
     CRYPTOGRAPHY_AVAILABLE = False
 
 
+POLICY_NONE_URI = 'http://opcfoundation.org/UA/SecurityPolicy#None'
+
+
 def require_cryptography(obj):
     """
     Raise exception if cryptography module is not available.
@@ -448,4 +451,6 @@ def encrypt_asymmetric(pubkey, data, policy_uri):
         if policy_uri == cls.URI:
             return (cls.encrypt_asymmetric(pubkey, data),
                     cls.AsymmetricEncryptionURI)
+    if not policy_uri or policy_uri == POLICY_NONE_URI:
+        return (data, '')
     raise UaError("Unsupported security policy `{}`".format(policy_uri))