Move signature code into fedireads.signatures.

fedireads/broadcast.py

@@ -1,15 +1,11 @@
 ''' send out activitypub messages '''
 import json
-from urllib.parse import urlparse
-from base64 import b64encode
-from Crypto.PublicKey import RSA
-from Crypto.Signature import pkcs1_15
-from Crypto.Hash import SHA256
 from django.utils.http import http_date
 import requests
 
 from fedireads import models
 from fedireads.tasks import app
+from fedireads.signatures import make_signature
 
 
 def get_public_recipients(user, software=None):
@@ -63,24 +59,6 @@ def broadcast_task(sender_id, activity, recipients):
     return errors
 
 
-def make_signature(sender, destination, date):
-    inbox_parts = urlparse(destination)
-    signature_headers = [
-        '(request-target): post %s' % inbox_parts.path,
-        'host: %s' % inbox_parts.netloc,
-        'date: %s' % date,
-    ]
-    message_to_sign = '\n'.join(signature_headers)
-    signer = pkcs1_15.new(RSA.import_key(sender.private_key))
-    signed_message = signer.sign(SHA256.new(message_to_sign.encode('utf8')))
-    signature = {
-        'keyId': '%s#main-key' % sender.remote_id,
-        'algorithm': 'rsa-sha256',
-        'headers': '(request-target) host date',
-        'signature': b64encode(signed_message).decode('utf8'),
-    }
-    return ','.join('%s="%s"' % (k, v) for (k, v) in signature.items())
-
 def sign_and_send(sender, activity, destination):
     ''' crpyto whatever and http junk '''
     now = http_date()

fedireads/incoming.py

@@ -1,21 +1,18 @@
 ''' handles all of the activity coming in to the server '''
 import json
-from base64 import b64decode
 from urllib.parse import urldefrag
+import requests
 
-from Crypto.Hash import SHA256
-from Crypto.PublicKey import RSA
-from Crypto.Signature import pkcs1_15
 import django.db.utils
 from django.http import HttpResponse
 from django.http import HttpResponseBadRequest, HttpResponseNotFound
 from django.views.decorators.csrf import csrf_exempt
-import requests
 
 from fedireads import books_manager, models, outgoing
 from fedireads import status as status_builder
 from fedireads.remote_user import get_or_create_remote_user
 from fedireads.tasks import app
+from fedireads.signatures import Signature
 
 
 @csrf_exempt
@@ -48,7 +45,16 @@ def shared_inbox(request):
         return HttpResponseBadRequest()
 
     try:
-        verify_signature(activity.get('actor'), request)
+        signature = Signature.parse(request)
+
+        key_actor = urldefrag(signature.key_id).url
+        if key_actor != activity.get('actor'):
+            print("Wrong sig: ", key_actor, activity.get('actor'))
+            raise ValueError("Wrong actor created signature.")
+
+        key = get_public_key(key_actor)
+
+        signature.verify(key, request)
     except ValueError:
         return HttpResponse(status=401)
 
@@ -88,7 +94,6 @@ def get_public_key(key_actor):
     try:
         user = models.User.objects.get(remote_id=key_actor)
         public_key = user.public_key
-        actor = user.remote_id
     except models.User.DoesNotExist:
         response = requests.get(
             key_actor,
@@ -99,49 +104,7 @@ def get_public_key(key_actor):
         user_data = response.json()
         public_key = user_data['publicKey']['publicKeyPem']
 
-    return RSA.import_key(public_key)
-
-def verify_signature(required_actor, request):
-    ''' verify rsa signature '''
-    signature_dict = {}
-    for pair in request.headers['Signature'].split(','):
-        k, v = pair.split('=', 1)
-        v = v.replace('"', '')
-        signature_dict[k] = v
-
-    try:
-        key_id = signature_dict['keyId']
-        headers = signature_dict['headers']
-        signature = b64decode(signature_dict['signature'])
-    except KeyError:
-        raise ValueError('Invalid auth header')
-
-    # TODO Use the fragment - actors can have multiple keys?
-    key_actor = urldefrag(key_id).url
-
-    if key_actor != required_actor:
-        raise ValueError("Wrong actor created signature.")
-
-    key = get_public_key(key_actor)
-
-    comparison_string = []
-    for signed_header_name in headers.split(' '):
-        if signed_header_name == '(request-target)':
-            comparison_string.append('(request-target): post %s' % request.path)
-        else:
-            comparison_string.append('%s: %s' % (
-                signed_header_name,
-                request.headers[signed_header_name]
-            ))
-    comparison_string = '\n'.join(comparison_string)
-
-    signer = pkcs1_15.new(key)
-    digest = SHA256.new()
-    digest.update(comparison_string.encode())
-
-    # raises a ValueError if it fails
-    signer.verify(digest, signature)
-
+    return public_key
 
 @app.task
 def handle_follow(activity):

fedireads/models/user.py

@@ -1,6 +1,4 @@
 ''' database schema for user data '''
-from Crypto import Random
-from Crypto.PublicKey import RSA
 from django.contrib.auth.models import AbstractUser
 from django.db import models
 from django.dispatch import receiver
@@ -8,6 +6,7 @@ from django.dispatch import receiver
 from fedireads import activitypub
 from fedireads.models.shelf import Shelf
 from fedireads.settings import DOMAIN
+from fedireads.signatures import create_key_pair
 from .base_model import FedireadsModel
 
 
@@ -158,10 +157,7 @@ def execute_before_save(sender, instance, *args, **kwargs):
     instance.shared_inbox = 'https://%s/inbox' % DOMAIN
     instance.outbox = '%s/outbox' % instance.remote_id
     if not instance.private_key:
-        random_generator = Random.new().read
-        key = RSA.generate(1024, random_generator)
-        instance.private_key = key.export_key().decode('utf8')
-        instance.public_key = key.publickey().export_key().decode('utf8')
+        instance.private_key, instance.public_key = create_key_pair()
 
 
 @receiver(models.signals.post_save, sender=User)

fedireads/signatures.py

@@ -0,0 +1,82 @@
+from urllib.parse import urlparse
+from base64 import b64encode, b64decode
+
+from Crypto import Random
+from Crypto.PublicKey import RSA
+from Crypto.Signature import pkcs1_15 #pylint: disable=no-name-in-module
+from Crypto.Hash import SHA256
+
+
+def create_key_pair():
+    random_generator = Random.new().read
+    key = RSA.generate(1024, random_generator)
+    private_key = key.export_key().decode('utf8')
+    public_key = key.publickey().export_key().decode('utf8')
+
+    return private_key, public_key
+
+
+def make_signature(sender, destination, date):
+    inbox_parts = urlparse(destination)
+    signature_headers = [
+        '(request-target): post %s' % inbox_parts.path,
+        'host: %s' % inbox_parts.netloc,
+        'date: %s' % date,
+    ]
+    message_to_sign = '\n'.join(signature_headers)
+    signer = pkcs1_15.new(RSA.import_key(sender.private_key))
+    signed_message = signer.sign(SHA256.new(message_to_sign.encode('utf8')))
+    signature = {
+        'keyId': '%s#main-key' % sender.remote_id,
+        'algorithm': 'rsa-sha256',
+        'headers': '(request-target) host date',
+        'signature': b64encode(signed_message).decode('utf8'),
+    }
+    return ','.join('%s="%s"' % (k, v) for (k, v) in signature.items())
+
+
+class Signature:
+    def __init__(self, key_id, headers, signature):
+        self.key_id = key_id
+        self.headers = headers
+        self.signature = signature
+
+    @classmethod
+    def parse(cls, request):
+        signature_dict = {}
+        for pair in request.headers['Signature'].split(','):
+            k, v = pair.split('=', 1)
+            v = v.replace('"', '')
+            signature_dict[k] = v
+
+        try:
+            key_id = signature_dict['keyId']
+            headers = signature_dict['headers']
+            signature = b64decode(signature_dict['signature'])
+        except KeyError:
+            raise ValueError('Invalid auth header')
+
+        return cls(key_id, headers, signature)
+
+    def verify(self, public_key, request):
+        ''' verify rsa signature '''
+        public_key = RSA.import_key(public_key)
+
+        comparison_string = []
+        for signed_header_name in self.headers.split(' '):
+            if signed_header_name == '(request-target)':
+                comparison_string.append(
+                    '(request-target): post %s' % request.path)
+            else:
+                comparison_string.append('%s: %s' % (
+                    signed_header_name,
+                    request.headers[signed_header_name]
+                ))
+        comparison_string = '\n'.join(comparison_string)
+
+        signer = pkcs1_15.new(public_key)
+        digest = SHA256.new()
+        digest.update(comparison_string.encode())
+
+        # raises a ValueError if it fails
+        signer.verify(digest, self.signature)

fedireads/tests/test_signing.py

@@ -1,18 +1,15 @@
 from collections import namedtuple
 from urllib.parse import urlsplit
 
-from Crypto import Random
-from Crypto.PublicKey import RSA
-
 import responses
 
 from django.test import TestCase, Client
 from django.utils.http import http_date
 
 from fedireads.models import User
-from fedireads.broadcast import make_signature
 from fedireads.activitypub import get_follow_request
 from fedireads.settings import DOMAIN
+from fedireads.signatures import create_key_pair, make_signature
 
 Sender = namedtuple('Sender', ('remote_id', 'private_key', 'public_key'))
 
@@ -22,10 +19,7 @@ class Signature(TestCase):
         self.rat = User.objects.create_user('rat', 'rat@example.com', '')
         self.cat = User.objects.create_user('cat', 'cat@example.com', '')
 
-        random_generator = Random.new().read
-        key = RSA.generate(1024, random_generator)
-        private_key = key.export_key().decode('utf8')
-        public_key = key.publickey().export_key().decode('utf8')
+        private_key, public_key = create_key_pair()
 
         self.fake_remote = Sender(
             'http://localhost/user/remote',
@@ -76,7 +70,8 @@ class Signature(TestCase):
         now = http_date()
         sender = self.fake_remote
         signature = make_signature(sender, self.rat.inbox, now)
-        assert self.send_follow(sender, signature, now).status_code == 200
+        response = self.send_follow(sender, signature, now)
+        self.assertEqual(response.status_code, 200)
 
     @responses.activate
     def test_nonexistent_signer(self):
@@ -89,4 +84,5 @@ class Signature(TestCase):
         now = http_date()
         sender = self.fake_remote
         signature = make_signature(sender, self.rat.inbox, now)
-        assert self.send_follow(sender, signature, now).status_code == 401
+        response = self.send_follow(sender, signature, now)
+        self.assertEqual(response.status_code, 401)