feature/sign-adds-to-existing

1 files changed, 37 insertions, 31 deletions

diff --git a/src/mailman_pgp/pgp/mime_multisig.py b/src/mailman_pgp/pgp/mime_multisig.py
index ced90fa..c7edf60 100644
--- a/src/mailman_pgp/pgp/mime_multisig.py
+++ b/src/mailman_pgp/pgp/mime_multisig.py
@@ -15,7 +15,7 @@
 # You should have received a copy of the GNU General Public License along with
 # this program.  If not, see <http://www.gnu.org/licenses/>.
 
-""""""
+"""MIMEWrapper with multiple signature as per draft-ietf-openpgp-multsig-02."""
 import copy
 from email import message_from_string
 from email.encoders import encode_7or8bit
@@ -23,8 +23,8 @@ from email.mime.application import MIMEApplication
 from email.mime.multipart import MIMEMultipart
 from email.utils import collapse_rfc2231_value
 
-from mailman.email.message import MultipartDigestMessage, Message
-from pgpy import PGPSignature, PGPDetachedSignature
+from mailman.email.message import Message, MultipartDigestMessage
+from pgpy import PGPDetachedSignature, PGPSignature
 
 from mailman_pgp.pgp.mime import MIMEWrapper
 from mailman_pgp.utils.email import copy_headers
@@ -41,7 +41,7 @@ class MIMEMultiSigWrapper(MIMEWrapper):
 
     def is_signed(self):
         """
-        Whether the whole message is MIME signed as per draft-ietf-openpgp-multsig-02.
+        Whether the message is signed as per draft-ietf-openpgp-multsig-02.
 
         :return: If the message is MIME signed.
         :rtype: bool
@@ -74,32 +74,36 @@ class MIMEMultiSigWrapper(MIMEWrapper):
                 continue
             yield sig
 
-    def _wrap_signed_multiple(self, msg, signature):
+    def _wrap_signed_multiple(self, msg, payload_msg, signatures, signature):
         """
         As per draft-ietf-openpgp-multsig-02.
 
         :param msg:
+        :param payload_msg:
+        :param signatures:
         :param signature:
         :return:
         """
         micalg = ', '.join(self._micalg(sig.hash_algorithm)
                            for sig in signature)
         out = MultipartDigestMessage('signed', micalg=micalg,
-                                     protocol=MIMEWrapper._signed_type)
+                                     protocol='multipart/mixed')
         out.preamble = MIMEMultiSigWrapper._signature_preamble
 
         second_part = MIMEMultipart()
-        for sig in signature:
-            sig_part = MIMEApplication(_data=str(sig),
-                                       _subtype=MIMEWrapper._signature_subtype,
-                                       _encoder=encode_7or8bit,
-                                       name='signature.asc')
-            sig_part.add_header('Content-Description',
-                                'OpenPGP digital signature')
-            sig_part.add_header('Content-Disposition', 'attachment',
-                                filename='signature.asc')
-            second_part.attach(sig_part)
-        out.attach(copy.deepcopy(msg))
+        for sig in signatures:
+            second_part.attach(copy.deepcopy(sig))
+
+        sig_part = MIMEApplication(_data=str(signature),
+                                   _subtype=MIMEWrapper._signature_subtype,
+                                   _encoder=encode_7or8bit,
+                                   name='signature.asc')
+        sig_part.add_header('Content-Description',
+                            'OpenPGP digital signature')
+        sig_part.add_header('Content-Disposition', 'attachment',
+                            filename='signature.asc')
+        second_part.attach(sig_part)
+        out.attach(copy.deepcopy(payload_msg))
         out.attach(second_part)
         copy_headers(msg, out)
         return out
@@ -115,19 +119,21 @@ class MIMEMultiSigWrapper(MIMEWrapper):
         :return: The signed message.
         :rtype: mailman.email.message.Message
         """
+
         if self.is_signed():
-            payload = next(iter(self.get_signed()))
-            signature = PGPDetachedSignature()
-            for sig in self.get_signature():
-                signature |= sig
-            signature |= key.sign(payload, hash=hash)
-            return self._wrap_signed_multiple(self.msg, signature)
+            payload_msg = self.msg.get_payload(0)
+            signatures = [part for part in self.msg.get_payload(1)]
         else:
-            super().sign(key, hash)
+            payload_msg = self.msg
+            signatures = []
+        signature = PGPDetachedSignature()
+        signature |= key.sign(payload_msg.as_string(), hash=hash)
+        return self._wrap_signed_multiple(self.msg, payload_msg, signatures,
+                                          signature)
 
     def verify(self, key):
         """
-        Verify the signature of this message with key.
+        Verify the signatures of this message with key.
 
         :param key: The key to verify with.
         :type key: pgpy.PGPKey
@@ -136,7 +142,11 @@ class MIMEMultiSigWrapper(MIMEWrapper):
         """
         clear_text = next(iter(self.get_signed()))
         for signature in self.get_signature():
-            yield key.verify(clear_text, signature)
+            try:
+                verification = key.verify(clear_text, signature)
+            except:
+                continue
+            yield verification
 
     def decrypt(self, key):
         """
@@ -156,10 +166,6 @@ class MIMEMultiSigWrapper(MIMEWrapper):
 
         out = message_from_string(dmsg, _class=Message)
         if decrypted.is_signed:
-            if len(decrypted.signatures) != 1:
-                out = self._wrap_signed_multiple(out,
-                                                 decrypted.detached_signature)
-            else:
-                out = self._wrap_signed(out, decrypted.signatures.pop())
+            out = self._wrap_signed_multiple(out, decrypted.detached_signature)
         copy_headers(self.msg, out)
         return out