lbry-sdk/lbrynet/cryptstream/CryptStreamCreator.py

155 lines
5.3 KiB
Python
Raw Normal View History

2015-08-20 17:27:15 +02:00
"""
Utility for creating Crypt Streams, which are encrypted blobs and associated metadata.
"""
import logging
2017-09-07 21:38:47 +02:00
from twisted.internet import interfaces, defer
from zope.interface import implements
2015-08-20 17:27:15 +02:00
from Crypto import Random
from Crypto.Cipher import AES
from lbrynet.cryptstream.CryptBlob import CryptStreamBlobMaker
log = logging.getLogger(__name__)
2017-09-07 21:38:47 +02:00
class CryptStreamCreator(object):
"""
Create a new stream with blobs encrypted by a symmetric cipher.
2015-08-20 17:27:15 +02:00
2016-11-04 17:39:52 +01:00
Each blob is encrypted with the same key, but each blob has its
own initialization vector which is associated with the blob when
the blob is associated with the stream.
"""
2017-09-07 21:38:47 +02:00
implements(interfaces.IConsumer)
2015-08-20 17:27:15 +02:00
def __init__(self, blob_manager, name=None, key=None, iv_generator=None):
2016-11-04 17:39:52 +01:00
"""@param blob_manager: Object that stores and provides access to blobs.
2015-08-20 17:27:15 +02:00
@type blob_manager: BlobManager
@param name: the name of the stream, which will be presented to the user
@type name: string
2016-11-04 17:39:52 +01:00
@param key: the raw AES key which will be used to encrypt the
blobs. If None, a random key will be generated.
2015-08-20 17:27:15 +02:00
@type key: string
2016-11-04 17:39:52 +01:00
@param iv_generator: a generator which yields initialization
vectors for the blobs. Will be called once for each blob.
2015-08-20 17:27:15 +02:00
@type iv_generator: a generator function which yields strings
@return: None
"""
self.blob_manager = blob_manager
2017-09-07 21:38:47 +02:00
self.name = name
2015-08-20 17:27:15 +02:00
self.key = key
if iv_generator is None:
self.iv_generator = self.random_iv_generator()
else:
self.iv_generator = iv_generator
2017-09-07 21:38:47 +02:00
self.stopped = True
self.producer = None
self.streaming = None
self.blob_count = -1
self.current_blob = None
self.finished_deferreds = []
def registerProducer(self, producer, streaming):
from twisted.internet import reactor
self.producer = producer
self.streaming = streaming
self.stopped = False
if streaming is False:
reactor.callLater(0, self.producer.resumeProducing)
def unregisterProducer(self):
self.stopped = True
self.producer = None
def stop(self):
"""Stop creating the stream. Create the terminating zero-length blob."""
log.debug("stop has been called for StreamCreator")
self.stopped = True
if self.current_blob is not None:
current_blob = self.current_blob
d = current_blob.close()
d.addCallback(self._blob_finished)
d.addErrback(self._error)
self.finished_deferreds.append(d)
self.current_blob = None
self._finalize()
dl = defer.DeferredList(self.finished_deferreds)
dl.addCallback(lambda _: self._finished())
dl.addErrback(self._error)
return dl
# TODO: move the stream creation process to its own thread and
# remove the reactor from this process.
def write(self, data):
from twisted.internet import reactor
self._write(data)
if self.stopped is False and self.streaming is False:
reactor.callLater(0, self.producer.resumeProducing)
2015-08-20 17:27:15 +02:00
@staticmethod
def random_iv_generator():
while 1:
yield Random.new().read(AES.block_size)
def setup(self):
"""Create the symmetric key if it wasn't provided"""
if self.key is None:
self.key = Random.new().read(AES.block_size)
return defer.succeed(True)
def _finalize(self):
"""
Finalize a stream by adding an empty
blob at the end, this is to indicate that
the stream has ended. This empty blob is not
saved to the blob manager
"""
log.debug("_finalize has been called")
2015-08-20 17:27:15 +02:00
self.blob_count += 1
iv = self.iv_generator.next()
final_blob_creator = self.blob_manager.get_blob_creator()
final_blob = self._get_blob_maker(iv, final_blob_creator)
d = final_blob.close()
d.addCallback(self._blob_finished)
self.finished_deferreds.append(d)
def _write(self, data):
while len(data) > 0:
if self.current_blob is None:
self.next_blob_creator = self.blob_manager.get_blob_creator()
2015-08-20 17:27:15 +02:00
self.blob_count += 1
iv = self.iv_generator.next()
self.current_blob = self._get_blob_maker(iv, self.next_blob_creator)
2015-08-20 17:27:15 +02:00
done, num_bytes_written = self.current_blob.write(data)
data = data[num_bytes_written:]
if done is True:
should_announce = self.blob_count == 0
d = self.current_blob.close()
d.addCallback(self._blob_finished)
d.addCallback(lambda blob_info: self.blob_manager.creator_finished(blob_info,
should_announce))
self.finished_deferreds.append(d)
2015-08-20 17:27:15 +02:00
self.current_blob = None
def _get_blob_maker(self, iv, blob_creator):
2016-11-04 17:39:52 +01:00
return CryptStreamBlobMaker(self.key, iv, self.blob_count, blob_creator)
2017-09-07 21:38:47 +02:00
def _error(self, error):
log.error(error)
def _finished(self):
raise NotImplementedError()
def _blob_finished(self, blob_info):
raise NotImplementedError()