V5.1 Specification updates

ddht/abc.py

@@ -22,7 +22,7 @@
 
 from ddht.base_message import BaseMessage
 from ddht.boot_info import BootInfo
-from ddht.typing import JSON, IDNonce, SessionKeys
+from ddht.typing import JSON, SessionKeys
 
 TAddress = TypeVar("TAddress", bound="AddressAPI")
 
@@ -177,8 +177,12 @@ def iter_all_random(self) -> Iterator[NodeID]:
  ...
 
 
-class HandshakeSchemeAPI(ABC):
+TSignatureInputs = TypeVar("TSignatureInputs")
+
+
+class HandshakeSchemeAPI(ABC, Generic[TSignatureInputs]):
  identity_scheme: Type[IdentitySchemeAPI]
+ signature_inputs_cls: Type[TSignatureInputs]
 
  #
  # Handshake
@@ -204,7 +208,7 @@ def compute_session_keys(
  remote_public_key: bytes,
  local_node_id: NodeID,
  remote_node_id: NodeID,
- id_nonce: IDNonce,
+ salt: bytes,
  is_locally_initiated: bool,
  ) -> SessionKeys:
  """Compute the symmetric session keys."""
@@ -213,20 +217,15 @@ def compute_session_keys(
  @classmethod
  @abstractmethod
  def create_id_nonce_signature(
- cls, *, id_nonce: IDNonce, ephemeral_public_key: bytes, private_key: bytes
+ cls, *, signature_inputs: TSignatureInputs, private_key: bytes,
  ) -> bytes:
  """Sign an id nonce received during handshake."""
  ...
 
  @classmethod
  @abstractmethod
  def validate_id_nonce_signature(
- cls,
- *,
- id_nonce: IDNonce,
- ephemeral_public_key: bytes,
- signature: bytes,
- public_key: bytes,
+ cls, *, signature_inputs: TSignatureInputs, signature: bytes, public_key: bytes,
  ) -> None:
  """Validate the id nonce signature received from a peer."""
  ...
@@ -235,7 +234,7 @@ def validate_id_nonce_signature(
 # https://github.com/python/mypy/issues/5264#issuecomment-399407428
 if TYPE_CHECKING:
  HandshakeSchemeRegistryBaseType = UserDict[
- Type[IdentitySchemeAPI], Type[HandshakeSchemeAPI]
+ Type[IdentitySchemeAPI], Type[HandshakeSchemeAPI[Any]]
  ]
 else:
  HandshakeSchemeRegistryBaseType = UserDict
@@ -244,8 +243,8 @@ def validate_id_nonce_signature(
 class HandshakeSchemeRegistryAPI(HandshakeSchemeRegistryBaseType):
  @abstractmethod
  def register(
- self, handshake_scheme_class: Type[HandshakeSchemeAPI]
- ) -> Type[HandshakeSchemeAPI]:
+ self, handshake_scheme_class: Type[HandshakeSchemeAPI[TSignatureInputs]]
+ ) -> Type[HandshakeSchemeAPI[TSignatureInputs]]:
  ...
 
 

ddht/constants.py

@@ -17,7 +17,6 @@
 NEIGHBOURS_RESPONSE_ITEMS = 16
 AES128_KEY_SIZE = 16 # size of an AES218 key
 HKDF_INFO = b"discovery v5 key agreement"
-ID_NONCE_SIGNATURE_PREFIX = b"discovery-id-nonce"
 ENR_REPR_PREFIX = "enr:" # prefix used when printing an ENR
 MAX_ENR_SIZE = 300 # maximum allowed size of an ENR
 IP_V4_ADDRESS_ENR_KEY = b"ip"

ddht/encryption.py

@@ -24,7 +24,7 @@ def validate_nonce(nonce: bytes) -> None:
 
 
 def aesgcm_encrypt(
- key: AES128Key, nonce: Nonce, plain_text: bytes, authenticated_data: bytes
+ key: AES128Key, nonce: Nonce, plain_text: bytes, authenticated_data: bytes,
 ) -> bytes:
  validate_aes128_key(key)
  validate_nonce(nonce)
@@ -35,7 +35,7 @@ def aesgcm_encrypt(
 
 
 def aesgcm_decrypt(
- key: AES128Key, nonce: Nonce, cipher_text: bytes, authenticated_data: bytes
+ key: AES128Key, nonce: Nonce, cipher_text: bytes, authenticated_data: bytes,
 ) -> bytes:
  validate_aes128_key(key)
  validate_nonce(nonce)
@@ -44,7 +44,7 @@ def aesgcm_decrypt(
  try:
  plain_text = aesgcm.decrypt(nonce, cipher_text, authenticated_data)
  except InvalidTag as error:
- raise DecryptionError() from error
+ raise DecryptionError(str(error)) from error
  else:
  return plain_text
 

ddht/handshake_schemes.py

@@ -1,4 +1,3 @@
-from hashlib import sha256
 import secrets
 from typing import Tuple, Type
 
@@ -13,15 +12,15 @@
 from eth_typing import NodeID
 from eth_utils import ValidationError, encode_hex
 
-from ddht.abc import HandshakeSchemeAPI, HandshakeSchemeRegistryAPI
-from ddht.constants import AES128_KEY_SIZE, HKDF_INFO, ID_NONCE_SIGNATURE_PREFIX
-from ddht.typing import AES128Key, IDNonce, SessionKeys
+from ddht.abc import HandshakeSchemeAPI, HandshakeSchemeRegistryAPI, TSignatureInputs
+from ddht.constants import AES128_KEY_SIZE, HKDF_INFO
+from ddht.typing import AES128Key, SessionKeys
 
 
 class HandshakeSchemeRegistry(HandshakeSchemeRegistryAPI):
  def register(
- self, handshake_scheme_class: Type[HandshakeSchemeAPI]
- ) -> Type[HandshakeSchemeAPI]:
+ self, handshake_scheme_class: Type[HandshakeSchemeAPI[TSignatureInputs]]
+ ) -> Type[HandshakeSchemeAPI[TSignatureInputs]]:
  """Class decorator to register handshake schemes."""
  is_missing_identity_scheme = (
  not hasattr(handshake_scheme_class, "identity_scheme")
@@ -42,9 +41,6 @@ def register(
  return handshake_scheme_class
 
 
-default_handshake_scheme_registry = HandshakeSchemeRegistry()
-
-
 def ecdh_agree(private_key: bytes, public_key: bytes) -> bytes:
  """
  Perform the ECDH key agreement.
@@ -66,17 +62,14 @@ def ecdh_agree(private_key: bytes, public_key: bytes) -> bytes:
 
 
 def hkdf_expand_and_extract(
- secret: bytes,
- initiator_node_id: NodeID,
- recipient_node_id: NodeID,
- id_nonce: IDNonce,
+ secret: bytes, initiator_node_id: NodeID, recipient_node_id: NodeID, salt: bytes,
 ) -> Tuple[bytes, bytes, bytes]:
  info = b"".join((HKDF_INFO, initiator_node_id, recipient_node_id))
 
  hkdf = HKDF(
  algorithm=SHA256(),
  length=3 * AES128_KEY_SIZE,
- salt=id_nonce,
+ salt=salt,
  info=info,
  backend=cryptography_default_backend(),
  )
@@ -94,8 +87,7 @@ def hkdf_expand_and_extract(
  return initiator_key, recipient_key, auth_response_key
 
 
-@default_handshake_scheme_registry.register
-class V4HandshakeScheme(HandshakeSchemeAPI):
+class BaseV4HandshakeScheme(HandshakeSchemeAPI[TSignatureInputs]):
  identity_scheme = V4IdentityScheme
 
  #
@@ -119,7 +111,7 @@ def compute_session_keys(
  remote_public_key: bytes,
  local_node_id: NodeID,
  remote_node_id: NodeID,
- id_nonce: IDNonce,
+ salt: bytes,
  is_locally_initiated: bool,
  ) -> SessionKeys:
  secret = ecdh_agree(local_private_key, remote_public_key)
@@ -130,7 +122,7 @@ def compute_session_keys(
  initiator_node_id, recipient_node_id = remote_node_id, local_node_id
 
  initiator_key, recipient_key, auth_response_key = hkdf_expand_and_extract(
- secret, initiator_node_id, recipient_node_id, id_nonce
+ secret, initiator_node_id, recipient_node_id, salt,
  )
 
  if is_locally_initiated:
@@ -144,33 +136,6 @@ def compute_session_keys(
  auth_response_key=AES128Key(auth_response_key),
  )
 
- @classmethod
- def create_id_nonce_signature(
- cls, *, id_nonce: IDNonce, ephemeral_public_key: bytes, private_key: bytes
- ) -> bytes:
- private_key_object = PrivateKey(private_key)
- signature_input = cls.create_id_nonce_signature_input(
- id_nonce=id_nonce, ephemeral_public_key=ephemeral_public_key
- )
- signature = private_key_object.sign_msg_hash_non_recoverable(signature_input)
- return bytes(signature)
-
- @classmethod
- def validate_id_nonce_signature(
- cls,
- *,
- id_nonce: IDNonce,
- ephemeral_public_key: bytes,
- signature: bytes,
- public_key: bytes,
- ) -> None:
- signature_input = cls.create_id_nonce_signature_input(
- id_nonce=id_nonce, ephemeral_public_key=ephemeral_public_key
- )
- cls.identity_scheme.validate_signature(
- message_hash=signature_input, signature=signature, public_key=public_key
- )
-
  #
  # Helpers
  #
@@ -210,10 +175,3 @@ def validate_signature(
  f"Signature {encode_hex(signature)} is not valid for message hash "
  f"{encode_hex(message_hash)} and public key {encode_hex(public_key)}"
  )
-
- @classmethod
- def create_id_nonce_signature_input(
- cls, *, id_nonce: IDNonce, ephemeral_public_key: bytes
- ) -> bytes:
- preimage = b"".join((ID_NONCE_SIGNATURE_PREFIX, id_nonce, ephemeral_public_key))
- return sha256(preimage).digest()

ddht/tools/driver/abc.py

@@ -68,11 +68,11 @@ async def next_message(self) -> AnyInboundMessage:
  ...
 
  @abstractmethod
- async def send_ping(self, request_id: Optional[int] = None) -> PingMessage:
+ async def send_ping(self, request_id: Optional[bytes] = None) -> PingMessage:
  ...
 
  @abstractmethod
- async def send_pong(self, request_id: Optional[int] = None) -> PongMessage:
+ async def send_pong(self, request_id: Optional[bytes] = None) -> PongMessage:
  ...
 
 

ddht/tools/driver/session.py

@@ -2,6 +2,7 @@
 from typing import AsyncIterator, List, Optional
 
 from async_generator import asynccontextmanager
+from eth_utils import int_to_big_endian
 import trio
 
 from ddht.base_message import AnyInboundMessage, AnyOutboundMessage, BaseMessage
@@ -51,17 +52,17 @@ async def next_message(self) -> AnyInboundMessage:
  return await self.channels.inbound_message_receive_channel.receive()
 
  @no_hang
- async def send_ping(self, request_id: Optional[int] = None) -> PingMessage:
+ async def send_ping(self, request_id: Optional[bytes] = None) -> PingMessage:
  if request_id is None:
- request_id = secrets.randbits(32)
+ request_id = int_to_big_endian(secrets.randbits(32))
  message = PingMessage(request_id, self.node.enr.sequence_number)
  await self.send_message(message)
  return message
 
  @no_hang
- async def send_pong(self, request_id: Optional[int] = None) -> PongMessage:
+ async def send_pong(self, request_id: Optional[bytes] = None) -> PongMessage:
  if request_id is None:
- request_id = secrets.randbits(32)
+ request_id = int_to_big_endian(secrets.randbits(32))
  message = PongMessage(
  request_id,
  self.node.enr.sequence_number,
@@ -133,22 +134,20 @@ async def transmit(self) -> AsyncIterator[None]:
 
  @no_hang
  async def send_packet(self, packet: AnyPacket) -> None:
- if packet.header.source_node_id == self.initiator.node.node_id:
- await self.recipient.session.handle_inbound_envelope(
+ if packet.dest_node_id == self.initiator.node.node_id:
+ await self.initiator.session.handle_inbound_envelope(
  InboundEnvelope(
- packet=packet, sender_endpoint=self.initiator.node.endpoint,
+ packet=packet, sender_endpoint=self.recipient.node.endpoint,
  )
  )
- elif packet.header.source_node_id == self.recipient.node.node_id:
- await self.initiator.session.handle_inbound_envelope(
+ elif packet.dest_node_id == self.recipient.node.node_id:
+ await self.recipient.session.handle_inbound_envelope(
  InboundEnvelope(
- packet=packet, sender_endpoint=self.recipient.node.endpoint,
+ packet=packet, sender_endpoint=self.initiator.node.endpoint,
  )
  )
  else:
- raise Exception(
- f"No matching node-id: {packet.header.source_node_id.hex()}"
- )
+ raise Exception(f"No matching node-id: {packet.dest_node_id.hex()}")
 
  @no_hang
  async def handshake(self) -> None: