Establish an OffchainCondition type

nucypher/policy/conditions/evm.py

@@ -102,6 +102,51 @@ def _validate_chain(chain: int) -> None:
         )
 
 
+class OffchainCondition(AccessControlCondition):
+    """
+    An offchain condition is a condition that can be evaluated by reading from a JSON
+    endpoint or other offchain source. It is used to evaluate conditions that cannot
+    be evaluated onchain.  This may be a REST service but the only requirement is that
+    the response is JSON and can be parsed using jsonpath.
+    """
+
+    CONDITION_TYPE = ConditionType.OFFCHAIN.value
+
+    class Schema(CamelCaseSchema):
+        name = fields.Str(required=False)
+        condition_type = fields.Str(
+            validate=validate.Equal(ConditionType), required=True
+        )
+        endpoint = fields.Str(required=True)
+
+        @post_load
+        def make(self, data, **kwargs):
+            return OffchainCondition(**data)
+
+    def __init__(
+        self,
+        endpoint: str,
+        condition_type: str = ConditionType.OFFCHAIN.value,
+        **kwargs,
+    ):
+
+        # internal
+        if condition_type != self.CONDITION_TYPE:
+            raise InvalidCondition(
+                f"{self.__class__.__name__} must be instantiated with the {self.CONDITION_TYPE} type."
+            )
+
+        self.endpoint = endpoint
+
+    def verify(
+        self, providers: Dict[int, Set[HTTPProvider]], **context
+    ) -> Tuple[bool, Any]:
+        """
+        Verifies the offchain condition is met by performing a read operation and evaluating the return value test.
+        """
+        raise NotImplementedError("Offchain conditions are not yet implemented.")
+
+
 class RPCCondition(AccessControlCondition):
     ETH_PREFIX = "eth_"
     ALLOWED_METHODS = {

nucypher/policy/conditions/lingo.py

@@ -74,6 +74,7 @@ class ConditionType(Enum):
     CONTRACT = "contract"
     RPC = "rpc"
     COMPOUND = "compound"
+    OFFCHAIN = "offchain"
 
     @classmethod
     def values(cls) -> List[str]: