[tor-commits] [stem/master] Fix key validation crypto

[atagar at torproject.org]

commit 3ff6435527b296ca0bafde2ea3989cc043507e07
Author: Damian Johnson <atagar at torproject.org>
Date:   Wed Mar 29 18:28:39 2017 +0200

    Fix key validation crypto
    
    Took some head scratching but figured out what I was buggering up. We should be
    validating the certificate bytes here, not the descriptor.
---
 stem/descriptor/certificate.py | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/stem/descriptor/certificate.py b/stem/descriptor/certificate.py
index 8888554..e29a079 100644
--- a/stem/descriptor/certificate.py
+++ b/stem/descriptor/certificate.py
@@ -208,20 +208,21 @@ class Ed25519CertificateV1(Ed25519Certificate):
     from nacl.exceptions import BadSignatureError
 
     descriptor_content = server_descriptor.get_bytes()
-    signing_key = server_descriptor.ed25519_master_key
+    signing_key = None
 
-    if not signing_key:
+    if server_descriptor.ed25519_master_key:
+      signing_key = nacl.signing.VerifyKey(server_descriptor.ed25519_master_key + '=', encoder = nacl.encoding.Base64Encoder)
+    else:
       for extension in self.extensions:
         if extension.type == ExtensionType.HAS_SIGNING_KEY:
-          signing_key = extension.data
+          signing_key = nacl.signing.VerifyKey(extension.data)
           break
 
     if not signing_key:
       raise ValueError('Server descriptor missing an ed25519 signing key')
 
     try:
-      verify_key = nacl.signing.VerifyKey(signing_key + '=', encoder = nacl.encoding.Base64Encoder)
-      verify_key.verify(descriptor_content[:-ED25519_SIGNATURE_LENGTH], self.signature)
+      signing_key.verify(base64.b64decode(self.encoded)[:-ED25519_SIGNATURE_LENGTH], self.signature)
     except BadSignatureError as exc:
       raise ValueError('Ed25519KeyCertificate signing key is invalid (%s)' % exc)