Can now fetch public key from actor url

api/funkwhale_api/federation/keys.py

@@ -0,0 +1,43 @@
+from cryptography.hazmat.primitives import serialization as crypto_serialization
+from cryptography.hazmat.primitives.asymmetric import rsa
+from cryptography.hazmat.backends import default_backend as crypto_default_backend
+
+import requests
+
+from . import exceptions
+
+
+def get_key_pair(size=2048):
+    key = rsa.generate_private_key(
+        backend=crypto_default_backend(),
+        public_exponent=65537,
+        key_size=size
+    )
+    private_key = key.private_bytes(
+        crypto_serialization.Encoding.PEM,
+        crypto_serialization.PrivateFormat.PKCS8,
+        crypto_serialization.NoEncryption())
+    public_key = key.public_key().public_bytes(
+        crypto_serialization.Encoding.PEM,
+        crypto_serialization.PublicFormat.PKCS1
+    )
+
+    return private_key, public_key
+
+
+def get_public_key(actor_url):
+    """
+    Given an actor_url, request it and extract publicKey data from
+    the response payload.
+    """
+    response = requests.get(actor_url)
+    response.raise_for_status()
+    payload = response.json()
+    try:
+        return {
+            'public_key_pem': payload['publicKey']['publicKeyPem'],
+            'id': payload['publicKey']['id'],
+            'owner': payload['publicKey']['owner'],
+        }
+    except KeyError:
+        raise exceptions.MalformedPayload(str(payload))