1 files changed, 17 insertions, 0 deletions

diff --git a/src/mailman_pgp/commands/eml_key.py b/src/mailman_pgp/commands/eml_key.py
index be0af44..1f39888 100644
--- a/src/mailman_pgp/commands/eml_key.py
+++ b/src/mailman_pgp/commands/eml_key.py
@@ -23,6 +23,7 @@ from mailman.interfaces.command import ContinueProcessing, IEmailCommand
 from mailman.interfaces.pending import IPendings
 from mailman.interfaces.subscriptions import ISubscriptionManager
 from mailman.interfaces.usermanager import IUserManager
+from pgpy.constants import KeyFlags
 from public import public
 from zope.component import getUtility
 from zope.interface import implementer
@@ -74,6 +75,14 @@ def _cmd_set(pgp_list, mlist, msg, msgdata, arguments, results):
               file=results)
         return ContinueProcessing.no
 
+    usage_flags = key.usage_flags()
+    for subkey in key.subkeys.values():
+        usage_flags |= subkey.usage_flags()
+    if KeyFlags.EncryptCommunications not in usage_flags:
+        print('Need a key which can be used to encrypt communications.',
+              file=results)
+        return ContinueProcessing.no
+
     email = get_email(msg)
     if not email:
         print('No email to subscribe with.', file=results)
@@ -219,6 +228,14 @@ def _cmd_change(pgp_list, mlist, msg, msgdata, arguments, results):
               file=results)
         return ContinueProcessing.no
 
+    usage_flags = key.usage_flags()
+    for subkey in key.subkeys.values():
+        usage_flags |= subkey.usage_flags()
+    if KeyFlags.EncryptCommunications not in usage_flags:
+        print('Need a key which can be used to encrypt communications.',
+              file=results)
+        return ContinueProcessing.no
+
     workflow = KeyChangeWorkflow(mlist, pgp_address, key)
     list(workflow)
     print('Key change request received.', file=results)