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Code Issues Projects Releases Wiki Activity

New re-encryption metadata format (#259)

pull/863/head
David Núñez 2019-03-21 00:22:19 +01:00
parent 3637d75805
commit e1d8362260
2 changed files with 14 additions and 20 deletions
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19
nucypher/network/server.py
View File

@ -325,20 +325,17 @@ def make_rest_app(
cfrag_byte_stream = b""
# This is Bob's signature of Alice's verifying key as ETH address.
alice_address_signature = bytes(work_order.alice_address_signature)
for item in work_order.items:
# Ursula signs on top of Bob's signature of the work item.
# Now both are committed to the same work item. See #259.
reencryption_metadata = bytes(stamp(bytes(item.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.
# She signs Alice's address too.
ursula_signature = stamp(capsule_signature + alice_address_signature)
capsule = item.capsule
capsule.set_correctness_keys(verifying=alices_verifying_key)
cfrag = pre.reencrypt(kfrag, capsule, metadata=bytes(ursula_signature))
cfrag = pre.reencrypt(kfrag, capsule, metadata=reencryption_metadata)
log.info(f"Re-encrypting for {capsule}, made {cfrag}.")
signature = stamp(bytes(cfrag) + bytes(capsule))
cfrag_byte_stream += VariableLengthBytestring(cfrag) + signature
reencryption_signature = stamp(bytes(item.signature) + bytes(cfrag))
cfrag_byte_stream += VariableLengthBytestring(cfrag) + reencryption_signature
# TODO: Put this in Ursula's datastore
work_order_tracker.append(work_order)

15
nucypher/policy/models.py
View File

@ -665,21 +665,18 @@ class WorkOrder:
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]
# Validate CFrag metadata
capsule_signature = bytes(self.capsule_signatures[counter])
metadata_input = capsule_signature + alice_address_signature
for item, (cfrag, reencryption_signature) in zip(self.items, cfrags_and_signatures):
# Validate re-encryption metadata
metadata_input = bytes(item.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):
# Validate re-encryption signatures
if reencryption_signature.verify(bytes(item.signature) + bytes(cfrag),
ursula_verifying_key):
good_cfrags.append(cfrag)
else:
raise InvalidSignature("{} is not properly signed by Ursula.".format(cfrag))