Verify OpenPGP signatures and display the result

Verify OpenPGP signatures as specified in RFC 3156. Display the result
in the header list above the message.

Signed-off-by: Justus Winter <4winter@informatik.uni-hamburg.de>

1 files changed, 18 insertions, 0 deletions

diff --git a/alot/crypto.py b/alot/crypto.py
index 6281ecfd..74f1f5c5 100644
--- a/alot/crypto.py
+++ b/alot/crypto.py
@@ -191,6 +191,24 @@ def encrypt(plaintext_str, keys=None):
     return encrypted
 
 
+def verify_detached(message, signature):
+    '''Verifies whether the message is authentic by checking the
+    signature.
+
+    :param message: the message as `str`
+    :param signature: a `str` containing an OpenPGP signature
+    :returns: a list of :class:`gpgme.Signature`
+    :raises: :class:`~alot.errors.GPGProblem` if the verification fails
+    '''
+    message_data = StringIO(message)
+    signature_data = StringIO(signature)
+    ctx = gpgme.Context()
+    try:
+        return ctx.verify(signature_data, message_data, None)
+    except gpgme.GpgmeError as e:
+        raise GPGProblem(e.message, code=e.code)
+
+
 def hash_key(key):
     """
     Returns a hash of the given key. This is a workaround for