Refactor feed code

ssb/feed.py

@@ -5,33 +5,69 @@ from hashlib import sha256
 
 from simplejson import dumps, loads
 
+from ssb.util import tag
+
 
 OrderedMsg = namedtuple('OrderedMsg', ('previous', 'author', 'sequence', 'timestamp', 'hash', 'content'))
 
 
+class NoPrivateKeyException(Exception):
+    pass
+
+
 def to_ordered(data):
     smsg = OrderedMsg(**data)
     return OrderedDict((k, getattr(smsg, k)) for k in smsg._fields)
 
 
+class Feed(object):
+    def __init__(self, public_key):
+        self.public_key = public_key
+
+    @property
+    def id(self):
+        return tag(self.public_key).decode('ascii')
+
+    def sign(self):
+        raise NoPrivateKeyException('Cannot use remote identity to sign (no private key!)')
+
+
+class LocalFeed(Feed):
+    def __init__(self, private_key):
+        self.private_key = private_key
+
+    @property
+    def public_key(self):
+        return self.private_key.verify_key
+
+    def sign(self, msg):
+        return self.private_key.sign(msg).signature
+
+
 class Message(object):
-    def __init__(self, keypair, content, timestamp=None, previous=None):
-        self.keypair = keypair
+    def __init__(self, feed, content, signature, sequence=1, timestamp=None, previous=None):
+        self.feed = feed
         self.content = content
+        self.signature = signature
+
         self.previous = previous
-        self.sequence = (self.previous.sequence + 1) if self.previous else 1
+        if self.previous:
+            self.sequence = self.previous.sequence + 1
+        else:
+            self.sequence = sequence
+
         self.timestamp = int(time.time() * 1000) if timestamp is None else timestamp
 
     @classmethod
-    def parse(cls, data, keypair):
+    def parse(cls, data, feed):
         obj = loads(data, object_pairs_hook=OrderedDict)
-        msg = cls(keypair, obj['content'], timestamp=obj['timestamp'])
+        msg = cls(feed, obj['content'], timestamp=obj['timestamp'])
         return msg, obj['signature']
 
     def to_dict(self, add_signature=True):
         obj = to_ordered({
             'previous': self.previous.key if self.previous else None,
-            'author': self.keypair.tag,
+            'author': self.feed.id,
             'sequence': self.sequence,
             'timestamp': self.timestamp,
             'hash': 'sha256',
@@ -42,12 +78,6 @@ class Message(object):
             obj['signature'] = self.signature
         return obj
 
-    @property
-    def signature(self):
-        # ensure ordering of keys and indentation of 2 characters, like ssb-keys
-        data = dumps(self.to_dict(add_signature=False), indent=2)
-        return (b64encode(bytes(self.keypair.sign(data.encode('ascii')))) + b'.sig.ed25519').decode('ascii')
-
     def verify(self, signature):
         return self.signature == signature
 
@@ -59,3 +89,15 @@ class Message(object):
     @property
     def key(self):
         return '%' + self.hash
+
+
+class LocalMessage(Message):
+    def __init__(self, feed, content, signature=None, sequence=1, timestamp=None, previous=None):
+        super(LocalMessage, self).__init__(feed, content, signature, sequence, timestamp, previous)
+        if signature is None:
+            self.signature = self.sign()
+
+    def sign(self):
+        # ensure ordering of keys and indentation of 2 characters, like ssb-keys
+        data = dumps(self.to_dict(add_signature=False), indent=2)
+        return (b64encode(bytes(self.feed.sign(data.encode('ascii')))) + b'.sig.ed25519').decode('ascii')

ssb/keys.py

@@ -1,28 +0,0 @@
-from base64 import b64encode
-
-from nacl.signing import SigningKey
-
-
-def tag(key):
-    """Create tag from publick key."""
-    return b'@' + b64encode(bytes(key)) + b'.ed25519'
-
-
-class KeyPair(object):
-    def __init__(self, seed=None):
-        self.private_key = SigningKey.generate() if seed is None else SigningKey(seed)
-        self.public_key = self.private_key.verify_key
-
-    @property
-    def tag(self):
-        return tag(self.public_key).decode('ascii')
-
-    @property
-    def private_tag(self):
-        return tag(self.private_key)
-
-    def sign(self, data):
-        return self.private_key.sign(data).signature
-
-    def __repr__(self):
-        return "<KeyPair {0.tag}>".format(self)

ssb/tests/test_feed.py

@@ -2,29 +2,29 @@ from base64 import b64decode
 from collections import OrderedDict
 
 import pytest
+from nacl.signing import SigningKey
 
-from ssb.feed import Message
-from ssb.keys import KeyPair
+from ssb.feed import LocalMessage, LocalFeed
 
 
 @pytest.fixture()
-def keypair():
+def feed():
     secret = b64decode('Mz2qkNOP2K6upnqibWrR+z8pVUI1ReA1MLc7QMtF2qQ=')
-    return KeyPair(secret)
+    return LocalFeed(SigningKey(secret))
 
 
-def test_keypair():
+def test_feed():
     secret = b64decode('Mz2qkNOP2K6upnqibWrR+z8pVUI1ReA1MLc7QMtF2qQ=')
-    kp = KeyPair(secret)
-    assert bytes(kp.private_key) == secret
-    assert bytes(kp.public_key) == b64decode('I/4cyN/jPBbDsikbHzAEvmaYlaJK33lW3UhWjNXjyrU=')
-    assert kp.tag == '@I/4cyN/jPBbDsikbHzAEvmaYlaJK33lW3UhWjNXjyrU=.ed25519'
+    feed = LocalFeed(SigningKey(secret))
+    assert bytes(feed.private_key) == secret
+    assert bytes(feed.public_key) == b64decode('I/4cyN/jPBbDsikbHzAEvmaYlaJK33lW3UhWjNXjyrU=')
+    assert feed.id == '@I/4cyN/jPBbDsikbHzAEvmaYlaJK33lW3UhWjNXjyrU=.ed25519'
 
 
-def test_message(keypair):
-    m1 = Message(keypair, OrderedDict([
+def test_message(feed):
+    m1 = LocalMessage(feed, OrderedDict([
         ('type', 'about'),
-        ('about', keypair.tag),
+        ('about', feed.id),
         ('name', 'neo'),
         ('description', 'The Chosen One')
     ]), timestamp=1495706260190)
@@ -35,9 +35,9 @@ def test_message(keypair):
         'lPsQ9P10OgeyH6u0unFgiI2wV/RQ7Q2x2ebxnXYCzsJ055TBMXphRADTKhOMS2EkUxXQ9k3amj5fnWPudGxwBQ==.sig.ed25519'
     assert m1.key == '%xRDqws/TrQmOd4aEwZ32jdLhP873ZKjIgHlggPR0eoo=.sha256'
 
-    m2 = Message(keypair, OrderedDict([
+    m2 = LocalMessage(feed, OrderedDict([
         ('type', 'about'),
-        ('about', keypair.tag),
+        ('about', feed.id),
         ('name', 'morpheus'),
         ('description', 'Dude with big jaw')
     ]), previous=m1, timestamp=1495706447426)

ssb/util.py

@@ -1,6 +1,6 @@
 import os
 import yaml
-from base64 import b64decode
+from base64 import b64decode, b64encode
 
 from nacl.signing import SigningKey
 
@@ -9,6 +9,11 @@ class ConfigException(Exception):
     pass
 
 
+def tag(key):
+    """Create tag from publick key."""
+    return b'@' + b64encode(bytes(key)) + b'.ed25519'
+
+
 def load_ssb_secret():
     """Load SSB keys from ~/.ssb"""
     with open(os.path.expanduser('~/.ssb/secret')) as f: