Runs black

bookwyrm/signatures.py

@@ -1,4 +1,4 @@
-''' signs activitypub activities '''
+""" signs activitypub activities """
 import hashlib
 from urllib.parse import urlparse
 import datetime
@@ -6,54 +6,56 @@ 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.Signature import pkcs1_15  # pylint: disable=no-name-in-module
 from Crypto.Hash import SHA256
 
 MAX_SIGNATURE_AGE = 300
 
+
 def create_key_pair():
-    ''' a new public/private key pair, used for creating new users '''
+    """ a new public/private key pair, used for creating new users """
     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 = key.export_key().decode("utf8")
+    public_key = key.publickey().export_key().decode("utf8")
 
     return private_key, public_key
 
 
 def make_signature(sender, destination, date, digest):
-    ''' uses a private key to sign an outgoing message '''
+    """ uses a private key to sign an outgoing message """
     inbox_parts = urlparse(destination)
     signature_headers = [
-        '(request-target): post %s' % inbox_parts.path,
-        'host: %s' % inbox_parts.netloc,
-        'date: %s' % date,
-        'digest: %s' % digest,
+        "(request-target): post %s" % inbox_parts.path,
+        "host: %s" % inbox_parts.netloc,
+        "date: %s" % date,
+        "digest: %s" % digest,
     ]
-    message_to_sign = '\n'.join(signature_headers)
+    message_to_sign = "\n".join(signature_headers)
     signer = pkcs1_15.new(RSA.import_key(sender.key_pair.private_key))
-    signed_message = signer.sign(SHA256.new(message_to_sign.encode('utf8')))
+    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 digest',
-        'signature': b64encode(signed_message).decode('utf8'),
+        "keyId": "%s#main-key" % sender.remote_id,
+        "algorithm": "rsa-sha256",
+        "headers": "(request-target) host date digest",
+        "signature": b64encode(signed_message).decode("utf8"),
     }
-    return ','.join('%s="%s"' % (k, v) for (k, v) in signature.items())
+    return ",".join('%s="%s"' % (k, v) for (k, v) in signature.items())
 
 
 def make_digest(data):
-    ''' creates a message digest for signing '''
-    return 'SHA-256=' + b64encode(hashlib.sha256(data.encode('utf-8'))\
-                        .digest()).decode('utf-8')
+    """ creates a message digest for signing """
+    return "SHA-256=" + b64encode(hashlib.sha256(data.encode("utf-8")).digest()).decode(
+        "utf-8"
+    )
 
 
 def verify_digest(request):
-    ''' checks if a digest is syntactically valid and matches the message '''
-    algorithm, digest = request.headers['digest'].split('=', 1)
-    if algorithm == 'SHA-256':
+    """ checks if a digest is syntactically valid and matches the message """
+    algorithm, digest = request.headers["digest"].split("=", 1)
+    if algorithm == "SHA-256":
         hash_function = hashlib.sha256
-    elif algorithm == 'SHA-512':
+    elif algorithm == "SHA-512":
         hash_function = hashlib.sha512
     else:
         raise ValueError("Unsupported hash function: {}".format(algorithm))
@@ -62,8 +64,10 @@ def verify_digest(request):
     if b64decode(digest) != expected:
         raise ValueError("Invalid HTTP Digest header")
 
+
 class Signature:
-    ''' read and validate incoming signatures '''
+    """ read and validate incoming signatures """
+
     def __init__(self, key_id, headers, signature):
         self.key_id = key_id
         self.headers = headers
@@ -71,42 +75,39 @@ class Signature:
 
     @classmethod
     def parse(cls, request):
-        ''' extract and parse a signature from an http request '''
+        """ extract and parse a signature from an http request """
         signature_dict = {}
-        for pair in request.headers['Signature'].split(','):
-            k, v = pair.split('=', 1)
-            v = v.replace('"', '')
+        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'])
+            key_id = signature_dict["keyId"]
+            headers = signature_dict["headers"]
+            signature = b64decode(signature_dict["signature"])
         except KeyError:
-            raise ValueError('Invalid auth header')
+            raise ValueError("Invalid auth header")
 
         return cls(key_id, headers, signature)
 
     def verify(self, public_key, request):
-        ''' verify rsa signature '''
-        if http_date_age(request.headers['date']) > MAX_SIGNATURE_AGE:
-            raise ValueError(
-                "Request too old: %s" % (request.headers['date'],))
+        """ verify rsa signature """
+        if http_date_age(request.headers["date"]) > MAX_SIGNATURE_AGE:
+            raise ValueError("Request too old: %s" % (request.headers["date"],))
         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)
+        for signed_header_name in self.headers.split(" "):
+            if signed_header_name == "(request-target)":
+                comparison_string.append("(request-target): post %s" % request.path)
             else:
-                if signed_header_name == 'digest':
+                if signed_header_name == "digest":
                     verify_digest(request)
-                comparison_string.append('%s: %s' % (
-                    signed_header_name,
-                    request.headers[signed_header_name]
-                ))
-        comparison_string = '\n'.join(comparison_string)
+                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()
@@ -117,7 +118,7 @@ class Signature:
 
 
 def http_date_age(datestr):
-    ''' age of a signature in seconds '''
-    parsed = datetime.datetime.strptime(datestr, '%a, %d %b %Y %H:%M:%S GMT')
+    """ age of a signature in seconds """
+    parsed = datetime.datetime.strptime(datestr, "%a, %d %b %Y %H:%M:%S GMT")
     delta = datetime.datetime.utcnow() - parsed
     return delta.total_seconds()