diff --git a/lib/credentials.py b/lib/credentials.py
index 64d4015aa..24dfec4de 100644
--- a/lib/credentials.py
+++ b/lib/credentials.py
@@ -665,6 +665,11 @@ def __repr__(self) -> str:
 
     def __str__(self) -> str:
         return ";".join(str(auth_set) for auth_set in self._requirements)
+    
+    def __contains__(self, cred_type: Union[CredentialType, str]) -> bool:
+        if isinstance(cred_type, str):
+            cred_type = CredentialType.from_string(cred_type)
+        return any(cred_type in group for group in self._requirements)
 
     def load(self, auth_method: str):
         for group in auth_method.split(";"):
@@ -1103,11 +1108,11 @@ def check_security_credentials(auth_method, params, client_int_name, entry_name,
     CredentialError: if the credentials in params don't match what is defined for the auth method
     """
 
-    auth_method_list = auth_method.split("+")
-    if not set(auth_method_list) & set(SUPPORTED_AUTH_METHODS):
+    try: 
+        auth_method = AuthenticationMethod(auth_method)
+    except CredentialError:
         logSupport.log.warning(
-            "None of the supported auth methods %s in provided auth methods: %s"
-            % (SUPPORTED_AUTH_METHODS, auth_method_list)
+            f"Invalid authentication method: \"{auth_method}\". Supported methods are: {SUPPORTED_AUTH_METHODS}"
         )
         return
 
@@ -1126,12 +1131,12 @@ def check_security_credentials(auth_method, params, client_int_name, entry_name,
         "AuthFile",
     }
 
-    if "scitoken" in auth_method_list or "frontend_scitoken" in params and scitoken_passthru:
+    if "scitoken" in auth_method or "frontend_scitoken" in params and scitoken_passthru:
         # TODO  check validity
         # TODO  Specifically, Add checks that no undesired credentials are
         #       sent also when token is used
         return
-    if "grid_proxy" in auth_method_list:
+    if "grid_proxy" in auth_method:
         if not scitoken_passthru:
             if "SubmitProxy" in params:
                 # v3+ protocol
@@ -1155,7 +1160,7 @@ def check_security_credentials(auth_method, params, client_int_name, entry_name,
         if "GlideinProxy" not in params and not scitoken_passthru:
             raise CredentialError("Glidein proxy cannot be found for client %s, skipping request" % client_int_name)
 
-        if "x509_cert" in auth_method_list:
+        if "x509_cert" in auth_method:
             # Validate both the public and private certs were passed
             if not (("PublicCert" in params) and ("PrivateCert" in params)):
                 # if not ('PublicCert' in params and 'PrivateCert' in params):
@@ -1173,7 +1178,7 @@ def check_security_credentials(auth_method, params, client_int_name, entry_name,
                     % (client_int_name, entry_name)
                 )
 
-        elif "rsa_key" in auth_method_list:
+        elif "rsa_key" in auth_method:
             # Validate both the public and private keys were passed
             if not (("PublicKey" in params) and ("PrivateKey" in params)):
                 # key pair is required, cannot service request
@@ -1190,7 +1195,7 @@ def check_security_credentials(auth_method, params, client_int_name, entry_name,
                     % (client_int_name, entry_name)
                 )
 
-        elif "auth_file" in auth_method_list:
+        elif "auth_file" in auth_method:
             # Validate auth_file is passed
             if not ("AuthFile" in params):
                 # auth_file is required, cannot service request
@@ -1207,7 +1212,7 @@ def check_security_credentials(auth_method, params, client_int_name, entry_name,
                     % (client_int_name, entry_name)
                 )
 
-        elif "username_password" in auth_method_list:
+        elif "username_password" in auth_method:
             # Validate username and password keys were passed
             if not (("Username" in params) and ("Password" in params)):
                 # username and password is required, cannot service request