Key Ceremony Update (#349)

* 🐛. Exponent modifier should not be zero

The exponent modifier should never be allowed to be zero to compute a polynomial coordinate.

In the same way a sequence_order should never be zero.

* Refactor Auxiliary Key

* Refactor Elgamal Key

* Refactor ElectionPolynomial

* Refactor Key Ceremony and Election Keys

- Remove GuardianKeyPair for migration to stateful class
- Migration of coefficient commitments and proofs into electionpublickey
- Removal of hash coefficient commitment specialty method 
- Update tests

* Update Publish and tests

* Update Guardian to Stateless

* Functional Key Ceremony Test

* Update Decryption

* ❓Remove optional on store

Optional on store shouldn't exist. This returns a list.

* Refactor Guardian

- Remove references to manually doing recovery key
- Ensure using new naming for election public key
- Correctly handle publish
- Change tests to rely on what can possibly be an outside verifier not necessarily a guardian.

* Refactor Key Ceremony

- Ensure key owner id and sequence order passed into all guardian key generation

* Implement Key Ceremony Helper

Key Ceremony Helper is both an example and a test implementation to perform the key ceremony. The idea is to provide an example and simply long testing sections.

* Updates to Functional Key Ceremony

* Add identity encrypt to ElectionGuard Test

Identity encrypt to the mock library to reduce the recoding of this function

* Update decryption tests

* Update Election Builder

* Update Key Ceremony Mediator

* Add Changes into Election Factory

* Update Decryption Mediator

* Update End to End Election Tests

Update the end to end election to demonstrate the entire election process including the new key ceremony changes.

* Review Adjustments

- Add property descriptions
- Add method descriptions

* Remove sequence order that is created with zero

* Update Ballot Box to use BALLOT_ID

* 🐛 Fix decryption mediator for ballots

* ✅ Add Decryption Tests

- Migrate some tests to decrypt_with_shares
- Add test_decryption tests
- Add Decryption Mediator tests

Author: keithrfung

Makefile

@@ -102,7 +102,6 @@ unit-tests:
 
 property-tests:
 	@echo ✅ PROPERTY TESTS
-	poetry run pytest tests/test_decryption_mediator.py
 	poetry run pytest tests/property
 
 integration-tests:

src/electionguard/auxiliary.py

@@ -3,41 +3,64 @@
 from .types import GUARDIAN_ID
 
 MESSAGE = str
-PUBLIC_KEY = str
-SECRET_KEY = str
+AUXILIARY_PUBLIC_KEY = str
+AUXILIARY_SECRET_KEY = str
 ENCRYPTED_MESSAGE = str
 
 
-class AuxiliaryKeyPair(NamedTuple):
-    """A tuple of a secret key and public key."""
+class AuxiliaryPublicKey(NamedTuple):
+    """A tuple of auxiliary public key and owner information that can be shared between guardians"""
 
-    secret_key: SECRET_KEY
-    """The secret or private key"""
-    public_key: PUBLIC_KEY
+    owner_id: GUARDIAN_ID
+    """
+    The unique identifier of the guardian owning the key
+    """
+
+    sequence_order: int
+    """
+    The sequence order of the auxiliary public key (usually the guardian's sequence order)
+    """
 
+    key: AUXILIARY_PUBLIC_KEY
+    """
+    A string representation of the Auxiliary public key that can be shared between guardians.
+    It is up to the external `AuxiliaryEncrypt` function to know how to parse this value
+    """
 
-class AuxiliaryPublicKey(NamedTuple):
-    """A tuple of auxiliary public key and owner information"""
+
+class AuxiliaryKeyPair(NamedTuple):
+    """A tuple of a secret key and public key."""
 
     owner_id: GUARDIAN_ID
     """
-    The unique identifier of the guardian
+    The unique identifier of the guardian owning the key
     """
 
     sequence_order: int
     """
     The sequence order of the auxiliary public key (usually the guardian's sequence order)
     """
 
-    key: PUBLIC_KEY
+    secret_key: AUXILIARY_SECRET_KEY
+    """The secret or private key"""
+
+    public_key: AUXILIARY_PUBLIC_KEY
     """
-    A string representation of the Auxiliary public key.
+    A string representation of the Auxiliary public key that can be shared between guardians.
     It is up to the external `AuxiliaryEncrypt` function to know how to parse this value
     """
 
+    def share(self) -> AuxiliaryPublicKey:
+        """Share the auxiliary public key and associated data"""
+        return AuxiliaryPublicKey(self.owner_id, self.sequence_order, self.public_key)
+
 
-AuxiliaryEncrypt = Callable[[MESSAGE, PUBLIC_KEY], Optional[ENCRYPTED_MESSAGE]]
+AuxiliaryEncrypt = Callable[
+    [MESSAGE, AUXILIARY_PUBLIC_KEY], Optional[ENCRYPTED_MESSAGE]
+]
 """A callable type that represents the auxiliary encryption scheme."""
 
-AuxiliaryDecrypt = Callable[[ENCRYPTED_MESSAGE, SECRET_KEY], Optional[MESSAGE]]
+AuxiliaryDecrypt = Callable[
+    [ENCRYPTED_MESSAGE, AUXILIARY_SECRET_KEY], Optional[MESSAGE]
+]
 """A callable type that represents the auxiliary decryption scheme."""

src/electionguard/ballot_box.py

@@ -12,6 +12,7 @@
 from .election import CiphertextElectionContext
 from .logs import log_warning
 from .manifest import InternalManifest
+from .types import BALLOT_ID
 
 
 @dataclass
@@ -83,7 +84,7 @@ def accept_ballot(
 
 def get_ballots(
     store: DataStore, state: Optional[BallotBoxState]
-) -> Dict[str, SubmittedBallot]:
+) -> Dict[BALLOT_ID, SubmittedBallot]:
     return {
         ballot_id: ballot
         for (ballot_id, ballot) in store.items()

src/electionguard/data_store.py

@@ -31,7 +31,7 @@ def __init__(self) -> None:
     def __iter__(self) -> Iterator:
         return iter(self._store.items())
 
-    def all(self) -> List[Optional[_U]]:
+    def all(self) -> List[_U]:
         """
         Get all `SubmittedBallot` from the store
         """