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Include Alice's address in the CFrag metadata and validate it

pull/507/head
David Núñez 2018-12-06 17:16:30 +01:00 committed by szotov
parent 5846005ca5
commit d605f06dd9
2 changed files with 25 additions and 8 deletions
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11
nucypher/network/server.py
View File

@ -315,15 +315,18 @@ def make_rest_app(
alices_verifying_key = UmbralPublicKey.from_bytes(verifying_key_bytes)
cfrag_byte_stream = b""
# This is Alice's verifying key as ETH address, signed by Bob
alice_address_signature = bytes(work_order.alice_address_signature)
for capsule, capsule_signature in zip(work_order.capsules, work_order.capsule_signatures):
# This is the capsule signed by Bob
capsule_signature = bytes(capsule_signature)
# Ursula signs on top of it. Now both are committed to the same capsule.
capsule_signed_by_both = bytes(stamp(capsule_signature))
# She signs Alice's address too.
ursula_signature = stamp(capsule_signature + alice_address_signature)
capsule.set_correctness_keys(verifying=alices_verifying_key)
cfrag = pre.reencrypt(kfrag, capsule, metadata=capsule_signed_by_both)
log.info("Re-encrypting for {}, made {}.".format(capsule, cfrag))
cfrag = pre.reencrypt(kfrag, capsule, metadata=bytes(ursula_signature))
log.info(f"Re-encrypting for {capsule}, made {cfrag}.")
signature = stamp(bytes(cfrag) + bytes(capsule))
cfrag_byte_stream += VariableLengthBytestring(cfrag) + signature

22
nucypher/policy/models.py
View File

@ -622,7 +622,7 @@ class WorkOrder:
(self.receipt_bytes,
msgpack.dumps(capsules_as_bytes),
msgpack.dumps(capsule_signatures_as_bytes),
self.alice_address,
self.alice_address, # TODO: if Ursula computes ETH address, we can remove this
self.alice_address_signature,
)
)
@ -631,13 +631,27 @@ class WorkOrder:
def complete(self, cfrags_and_signatures):
good_cfrags = []
if not len(self) == len(cfrags_and_signatures):
raise ValueError("Ursula gave back the wrong number of cfrags. She's up to something.")
raise ValueError("Ursula gave back the wrong number of cfrags. "
"She's up to something.")
alice_address_signature = bytes(self.alice_address_signature)
ursula_verifying_key = self.ursula.stamp.as_umbral_pubkey()
for counter, capsule in enumerate(self.capsules):
cfrag, signature = cfrags_and_signatures[counter]
if signature.verify(bytes(cfrag) + bytes(capsule), self.ursula.stamp.as_umbral_pubkey()):
# Validate CFrag metadata
capsule_signature = bytes(self.capsule_signatures[counter])
metadata_input = capsule_signature + alice_address_signature
metadata_as_signature = Signature.from_bytes(cfrag.proof.metadata)
if not metadata_as_signature.verify(metadata_input, ursula_verifying_key):
raise InvalidSignature("Invalid metadata for {}.".format(cfrag))
# Validate work order response signatures
if signature.verify(bytes(cfrag) + bytes(capsule), ursula_verifying_key):
good_cfrags.append(cfrag)
else:
raise self.ursula.InvalidSignature("This CFrag is not properly signed by Ursula.")
raise InvalidSignature("{} is not properly signed by Ursula.".format(cfrag))
else:
self.completed = maya.now()
return good_cfrags