104 lines
2.9 KiB
Python
104 lines
2.9 KiB
Python
import time
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from base64 import b64encode
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from collections import namedtuple, OrderedDict
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from hashlib import sha256
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from simplejson import dumps, loads
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from ssb.util import tag
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OrderedMsg = namedtuple('OrderedMsg', ('previous', 'author', 'sequence', 'timestamp', 'hash', 'content'))
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class NoPrivateKeyException(Exception):
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pass
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def to_ordered(data):
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smsg = OrderedMsg(**data)
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return OrderedDict((k, getattr(smsg, k)) for k in smsg._fields)
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class Feed(object):
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def __init__(self, public_key):
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self.public_key = public_key
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@property
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def id(self):
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return tag(self.public_key).decode('ascii')
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def sign(self):
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raise NoPrivateKeyException('Cannot use remote identity to sign (no private key!)')
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class LocalFeed(Feed):
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def __init__(self, private_key):
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self.private_key = private_key
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@property
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def public_key(self):
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return self.private_key.verify_key
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def sign(self, msg):
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return self.private_key.sign(msg).signature
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class Message(object):
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def __init__(self, feed, content, signature, sequence=1, timestamp=None, previous=None):
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self.feed = feed
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self.content = content
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self.signature = signature
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self.previous = previous
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if self.previous:
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self.sequence = self.previous.sequence + 1
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else:
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self.sequence = sequence
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self.timestamp = int(time.time() * 1000) if timestamp is None else timestamp
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@classmethod
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def parse(cls, data, feed):
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obj = loads(data, object_pairs_hook=OrderedDict)
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msg = cls(feed, obj['content'], timestamp=obj['timestamp'])
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return msg, obj['signature']
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def to_dict(self, add_signature=True):
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obj = to_ordered({
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'previous': self.previous.key if self.previous else None,
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'author': self.feed.id,
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'sequence': self.sequence,
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'timestamp': self.timestamp,
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'hash': 'sha256',
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'content': self.content
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})
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if add_signature:
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obj['signature'] = self.signature
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return obj
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def verify(self, signature):
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return self.signature == signature
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@property
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def hash(self):
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hash = sha256(dumps(self.to_dict(), indent=2).encode('ascii')).digest()
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return b64encode(hash).decode('ascii') + '.sha256'
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@property
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def key(self):
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return '%' + self.hash
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class LocalMessage(Message):
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def __init__(self, feed, content, signature=None, sequence=1, timestamp=None, previous=None):
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super(LocalMessage, self).__init__(feed, content, signature, sequence, timestamp, previous)
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if signature is None:
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self.signature = self.sign()
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def sign(self):
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# ensure ordering of keys and indentation of 2 characters, like ssb-keys
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data = dumps(self.to_dict(add_signature=False), indent=2)
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return (b64encode(bytes(self.feed.sign(data.encode('ascii')))) + b'.sig.ed25519').decode('ascii')
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