Using pyUmbral Signer as SignatureStamp's signing function.

nucypher/characters.py

@@ -19,7 +19,7 @@ from nucypher.crypto.api import secure_random, keccak_digest, encrypt_and_sign
 from nucypher.crypto.constants import PUBLIC_KEY_LENGTH
 from nucypher.crypto.kits import UmbralMessageKit
 from nucypher.crypto.powers import CryptoPower, SigningPower, EncryptingPower, DelegatingPower, NoSigningPower
-from nucypher.crypto.signature import Signature, signature_splitter, SignatureStamp, StrangerStamp
+from nucypher.crypto.signing import Signature, signature_splitter, SignatureStamp, StrangerStamp
 from nucypher.network import blockchain_client
 from nucypher.network.protocols import dht_value_splitter, dht_with_hrac_splitter
 from nucypher.network.server import NucypherDHTServer, NucypherSeedOnlyDHTServer, ProxyRESTServer
@@ -79,7 +79,8 @@ class Character(object):
         if is_me:
             self.network_middleware = network_middleware or NetworkyStuff()
             try:
-                self._stamp = SignatureStamp(self._crypto_power.power_ups(SigningPower).keypair)
+                signing_power = self._crypto_power.power_ups(SigningPower)
+                self._stamp = signing_power.get_signature_stamp()
             except NoSigningPower:
                 self._stamp = constants.NO_SIGNING_POWER
 
@@ -89,7 +90,7 @@ class Character(object):
             if network_middleware is not None:
                 raise TypeError(
                     "Can't attach network middleware to a Character who isn't me.  What are you even trying to do?")
-            self._stamp = StrangerStamp(self._crypto_power.power_ups(SigningPower).keypair)
+            self._stamp = StrangerStamp(self.public_key(SigningPower))
 
     def __eq__(self, other):
         return bytes(self.stamp) == bytes(other.stamp)

nucypher/crypto/powers.py

@@ -117,7 +117,7 @@ class DerivedKeyBasedPower(CryptoPowerUp):
 class SigningPower(KeyPairBasedPower):
     _keypair_class = SigningKeypair
     not_found_error = NoSigningPower
-    provides = ("sign", "generate_self_signed_cert")
+    provides = ("sign", "generate_self_signed_cert", "get_signature_stamp")
 
 
 class EncryptingPower(KeyPairBasedPower):

nucypher/crypto/signing.py

@@ -1,6 +1,6 @@
 from nucypher.crypto.api import keccak_digest
 from bytestring_splitter import BytestringSplitter
-from umbral.signing import Signature
+from umbral.signing import Signature, Signer
 
 signature_splitter = BytestringSplitter(Signature)
 
@@ -11,16 +11,16 @@ class SignatureStamp(object):
     key as bytes.
     """
 
-    def __init__(self, signing_keypair):
-        self._sign = signing_keypair.sign
-        self._as_bytes = bytes(signing_keypair.pubkey)
-        self._as_umbral_pubkey = signing_keypair.pubkey
+    def __init__(self, signing_key, signer: Signer=None):
+        self.__signer = signer
+        self._as_bytes = bytes(signing_key)
+        self._as_umbral_pubkey = signing_key
 
     def __bytes__(self):
         return self._as_bytes
 
     def __call__(self, *args, **kwargs):
-        return self._sign(*args, **kwargs)
+        return self.__signer(*args, **kwargs)
 
     def __hash__(self):
         return int.from_bytes(self, byteorder="big")
@@ -56,7 +56,6 @@ class StrangerStamp(SignatureStamp):
     """
     SignatureStamp of a stranger (ie, can only be used to glean public key, not to sign)
     """
-
     def __call__(self, *args, **kwargs):
         message = "This isn't your SignatureStamp; it belongs to (a Stranger).  You can't sign with it."
         raise TypeError(message)

nucypher/data_sources.py

@@ -1,17 +1,20 @@
 from nucypher.crypto.api import encrypt_and_sign
-from nucypher.crypto.signature import SignatureStamp
+from nucypher.crypto.powers import SigningPower
+from nucypher.crypto.signing import SignatureStamp
 from nucypher.keystore.keypairs import SigningKeypair
 from constant_sorrow.constants import NO_SIGNING_POWER
 from umbral.keys import UmbralPublicKey
+from umbral.signing import Signer
 
 
 class DataSource:
 
-    def __init__(self, policy_pubkey_enc, signer=NO_SIGNING_POWER, label=None):
+    def __init__(self, policy_pubkey_enc, signing_keypair=NO_SIGNING_POWER, label=None):
         self.policy_pubkey = policy_pubkey_enc
-        if signer is NO_SIGNING_POWER:
-            signer = SignatureStamp(SigningKeypair())  # TODO: Generate signing key properly.  #241
-        self.stamp = signer
+        if signing_keypair is NO_SIGNING_POWER:
+            signing_keypair = SigningKeypair()  # TODO: Generate signing key properly.  #241
+        signing_power = SigningPower(keypair=signing_keypair)
+        self.stamp = signing_power.get_signature_stamp()
         self.label = label
 
     def encapsulate_single_message(self, message):

nucypher/keystore/keypairs.py

@@ -7,8 +7,8 @@ from umbral.keys import UmbralPrivateKey, UmbralPublicKey
 from umbral import pre
 from umbral.config import default_curve
 from nucypher.crypto.kits import MessageKit
-from nucypher.crypto.signature import SignatureStamp
-from umbral.signing import Signature
+from nucypher.crypto.signing import SignatureStamp
+from umbral.signing import Signature, Signer
 
 
 class Keypair(object):
@@ -106,3 +106,7 @@ class SigningKeypair(Keypair):
     def generate_self_signed_cert(self, common_name):
         cryptography_key = self._privkey.to_cryptography_privkey()
         return generate_self_signed_certificate(common_name, default_curve(), cryptography_key)
+
+    def get_signature_stamp(self):
+        signer = Signer(self._privkey)
+        return SignatureStamp(signing_key=self.pubkey, signer=signer)

nucypher/keystore/keystore.py

@@ -1,6 +1,6 @@
 from typing import Union
 
-from nucypher.crypto.signature import Signature
+from nucypher.crypto.signing import Signature
 from bytestring_splitter import BytestringSplitter
 from nucypher.keystore.db.models import Key, PolicyArrangement, Workorder
 from umbral.fragments import KFrag

nucypher/network/protocols.py

@@ -5,7 +5,7 @@ from kademlia.utils import digest
 from constant_sorrow import default_constant_splitter, constants
 from nucypher.crypto.api import keccak_digest
 from nucypher.crypto.constants import PUBLIC_KEY_LENGTH, KECCAK_DIGEST_LENGTH
-from nucypher.crypto.signature import Signature
+from nucypher.crypto.signing import Signature
 from bytestring_splitter import BytestringSplitter
 from nucypher.network.node import NucypherNode
 from nucypher.network.routing import NucypherRoutingTable

nucypher/policy/models.py

@@ -12,7 +12,7 @@ from nucypher.characters import Bob, Ursula
 from nucypher.crypto.api import keccak_digest
 from nucypher.crypto.constants import KECCAK_DIGEST_LENGTH
 from nucypher.crypto.powers import SigningPower, DelegatingPower
-from nucypher.crypto.signature import Signature
+from nucypher.crypto.signing import Signature
 from nucypher.crypto.splitters import key_splitter
 from bytestring_splitter import BytestringSplitter
 from nucypher.blockchain.eth.policies import BlockchainArrangement

tests/crypto/test_bytestring_types.py

@@ -1,6 +1,6 @@
 import pytest
 from nucypher.crypto.api import secure_random
-from nucypher.crypto.signature import Signature
+from nucypher.crypto.signing import Signature
 from bytestring_splitter import BytestringSplitter
 
 

tests/crypto/test_signature.py

@@ -1,6 +1,6 @@
 from nucypher.crypto.api import ecdsa_sign
 from umbral.keys import UmbralPrivateKey
-from nucypher.crypto.signature import Signature
+from nucypher.crypto.signing import Signature
 
 
 def test_signature_can_verify():

tests/fixtures.py

@@ -11,7 +11,7 @@ from nucypher.characters import Alice, Bob
 from nucypher.keystore import keystore
 from nucypher.keystore.db import Base
 
-from nucypher.crypto.signature import SignatureStamp
+from nucypher.crypto.signing import SignatureStamp
 from nucypher.data_sources import DataSource
 from nucypher.keystore import keystore
 from nucypher.keystore.db import Base
@@ -97,7 +97,7 @@ def test_keystore():
 def capsule_side_channel(enacted_policy):
     signing_keypair = SigningKeypair()
     data_source = DataSource(policy_pubkey_enc=enacted_policy.public_key,
-                             signer=SignatureStamp(signing_keypair))
+                             signing_keypair=signing_keypair)
     message_kit, _signature = data_source.encapsulate_single_message(b"Welcome to the flippering.")
     return message_kit, data_source