settlement

cashu/core/base.py

@@ -1250,17 +1250,17 @@ class DlcOutcome(BaseModel):
     """
     Describes a DLC outcome
     """
-    k: Optional[str]      # The discrete log revealed by the oracle
+    k: Optional[str]      # The blinded attestation secret
     t: Optional[int]      # The timeout (claim when time is over)
-    P: str                # The payout structure associated with k
+    P: str                # The payout structure associated with this outcome
 
 class DlcSettlement(BaseModel):
     """
     Data used to settle an outcome of a DLC
     """
     dlc_root: str
-    outcome: DlcOutcome
-    merkle_proof: List[str]
+    outcome: Optional[DlcOutcome]
+    merkle_proof: Optional[List[str]]
     details: Optional[str]
 
 class DlcPayoutForm(BaseModel):

cashu/core/errors.py

@@ -119,4 +119,12 @@ class DlcNotFoundError(CashuError):
     code = 30002
 
     def __init__(self, **kwargs):
-        super().__init__(self.detail, self.code)
+        super().__init__(self.detail, self.code)
+
+class DlcSettlementFail(CashuError):
+    detail = "settlement verification failed: "
+    code = 30003
+
+    def __init__(self, **kwargs):
+        super().__init__(self.detail, self.code)
+        self.detail += kwargs['detail']

cashu/mint/ledger.py

@@ -23,7 +23,8 @@
     DlcBadInput,
     DlcFundingProof,
     DLCWitness,
-    DiscreetLogContract
+    DiscreetLogContract,
+    DlcSettlement,
 )
 from ..core.crypto import b_dhke
 from ..core.crypto.dlc import sign_dlc
@@ -51,6 +52,8 @@
     PostMintQuoteRequest,
     PostDlcRegistrationRequest,
     PostDlcRegistrationResponse,
+    PostDlcSettleRequest,
+    PostDlcSettleResponse,
     GetDlcStatusResponse,
 )
 from ..core.settings import settings
@@ -1148,7 +1151,7 @@ async def register_dlc(self, request: PostDlcRegistrationRequest) -> PostDlcRegi
                 active_keyset_for_unit = next(
                     filter(
                         lambda k: k.active and k.unit == Unit[registration.unit],
-                        self.keysets.values()
+                        self.keysets.values(),
                     )
                 )
                 funding_privkey = next(iter(active_keyset_for_unit.private_keys.values()))
@@ -1157,10 +1160,9 @@ async def register_dlc(self, request: PostDlcRegistrationRequest) -> PostDlcRegi
                     registration.funding_amount,
                     funding_privkey,
                 )
-
                 funding_proof = DlcFundingProof(
                     dlc_root=registration.dlc_root,
-                    signature=signature.hex()
+                    signature=signature.hex(),
                 )
                 dlc = DiscreetLogContract(
                     settled=False,
@@ -1178,7 +1180,7 @@ async def register_dlc(self, request: PostDlcRegistrationRequest) -> PostDlcRegi
                         dlc_root=registration.dlc_root,
                         bad_inputs=[DlcBadInput(
                             index=-1,
-                            detail=e.detail
+                            detail=e.detail,
                         )]
                     ))
                 # DLC verification fail
@@ -1195,4 +1197,37 @@ async def register_dlc(self, request: PostDlcRegistrationRequest) -> PostDlcRegi
         return PostDlcRegistrationResponse(
             funded=[reg[1] for reg in registered],
             errors=errors if len(errors) > 0 else None,
-        )
+        )
+
+    '''
+    # UNFINISHED
+    async def settle_dlc(self, request: PostDlcSettleRequest) -> PostDlcSettleResponse:
+        """Settle DLCs once the oracle reveals the attestation secret or the timeout is over.
+            Args:
+                request (PostDlcSettleRequest): a request formatted following NUT-DLC spec
+            Returns:
+                PostDlcSettleResponse: Indicates which DLCs have been settled and potential errors.
+        """
+        logger.trace("settle called")
+        verified: List[DlcSettlement] = []
+        errors: List[DlcSettlement] = []
+        for settlement in request:
+            try:
+                # Verify inclusion of payout structure and associated attestation in the DLC
+                assert settlement.outcome and settlement.merkle_proof, "outcome or merkle proof not provided"
+                await self.verify_dlc_inclusion(settlement.dlc_root, settlement.outcome, settlement.merkle_proof)
+                verified.append(settlement)
+            except DlcSettlementFail, AssertionError as e:
+                errors.append(DlcSettlement(
+                    dlc_root=settlement.dlc_root,
+                    details=e.details if isinstance(e, DlcSettlementFail) else str(e)
+                ))
+        # Database dance:
+        settled, db_errors = await self.db_write._settle_dlc(verified)
+        errors += db_errors
+
+        return PostDlcSettleResponse(
+            settled=settled,
+            errors=errors if len(errors) > 0 else None,
+        )
+    '''

cashu/mint/verification.py

@@ -1,5 +1,7 @@
 from typing import Dict, List, Literal, Optional, Tuple, Union
 
+import json
+
 from loguru import logger
 from hashlib import sha256
 
@@ -12,6 +14,7 @@
     Unit,
     DlcBadInput,
     DLCWitness,
+    DlcOutcome,
 )
 from ..core.crypto import b_dhke
 from ..core.crypto.dlc import merkle_verify
@@ -25,6 +28,7 @@
     TransactionError,
     TransactionUnitError,
     DlcVerificationFail,
+    DlcSettlementFail,
 )
 from ..core.settings import settings
 from ..lightning.base import LightningBackend
@@ -475,3 +479,24 @@ def raise_if_err(err):
                     detail=exc.detail if exc else "input spending conditions verification failed" 
                 ))
         raise_if_err(errors)
+
+    async def _verify_dlc_payout(self, P: str):
+        try:
+            payout = json.loads(P)
+            if not isinstance(payout, dict):
+                raise DlcSettlementFail(detail="Provided payout structure is not a dictionary")
+            if not all([isinstance(k, str) and isinstance(v, int) for k, v in payout.items()]):
+                raise DlcSettlementFail(detail="Provided payout structure is not a dictionary mapping strings to integers")
+            for v in payout.values():
+                try:
+                    b = bytes.fromhex(v)
+                    if b[0] != b'\x02':
+                        raise DlcSettlementFail(detail="Provided payout structure contains incorrect public keys")
+                except ValueError as e:
+                    raise DlcSettlementFail(detail=str(e))
+        except json.JSONDecodeError as e:
+            raise DlcSettlementFail(detail="cannot decode the provided payout structure")
+
+    async def _verify_dlc_inclusion(self, dlc_root: str, outcome: DlcOutcome, merkle_proof: List[str]):
+        # Verify payout structure
+        await self._verify_dlc_payout(outcome.P)