WIP: Start with the changes needed for on-chain check

Signed-off-by: Sasha Bogicevic <sasha.bogicevic@iohk.io>

Author: v0d1ch

hydra-plutus/src/Hydra/Contract/Head.hs

@@ -672,7 +672,7 @@ checkFanout ScriptContext{scriptContextTxInfo = txInfo} closedDatum numberOfFano
 
   decommitUtxoHash = hashTxOuts $ L.take numberOfDecommitOutputs $ L.drop numberOfFanoutOutputs txInfoOutputs
 
-  ClosedDatum{utxoHash, alphaUTxOHash, omegaUTxOHash, parties, headId, contestationDeadline} = closedDatum
+  ClosedDatum{utxoHash, alphaUTxOHash, omegaUTxOHash, parties, headId, contestationDeadline, accumulatorHash, proof} = closedDatum
 
   TxInfo{txInfoOutputs} = txInfo
 

hydra-plutus/src/Hydra/Contract/HeadState.hs

@@ -61,6 +61,7 @@ data ClosedDatum = ClosedDatum
   -- ^ Spec: tfinal
   , accumulatorHash :: Hash
   -- ^ Spec: ηA. Digest of the accumulator
+  , proof :: BuiltinBLS12_381_G2_Element
   }
   deriving stock (Generic, Show)
 
@@ -86,7 +87,8 @@ data CloseRedeemer
     CloseInitial
   | -- | Any snapshot which doesn't contain anything to inc/decrement but snapshot number is higher than zero.
     CloseAny
-      {signature :: [Signature]}
+      { signature :: [Signature]
+      }
   | -- | Closing snapshot refers to the current state version
     CloseUnusedDec
       { signature :: [Signature]
@@ -187,6 +189,7 @@ data Input
       { numberOfFanoutOutputs :: Integer
       , numberOfCommitOutputs :: Integer
       , numberOfDecommitOutputs :: Integer
+      , crs :: [BuiltinBLS12_381_G1_Element]
       }
   deriving stock (Generic, Show)
 

hydra-tx/src/Hydra/Tx/Accumulator.hs

@@ -169,16 +169,15 @@ createMembershipProof ::
   -- | Common Reference String (CRS) for the cryptographic proof
   [Point2] ->
   -- | Returns a string: "Success: 0x..." or "Error: ..."
-  Text
+  ByteString
 createMembershipProof subsetElements (HydraAccumulator fullAcc) crs =
   -- Use getPolyCommitOverG2 to generate the proof
   case getPolyCommitOverG2 subsetElements fullAcc crs of
-    Left err -> "Error: " <> toText err
+    Left err -> "Error: " <> encodeUtf8 (toText err)
     Right proof ->
       -- Compress the Point2 to a ByteString and encode as hex
       let proofBytes = blsCompress proof
-          proofHex = decodeUtf8 $ Base16.encode proofBytes
-       in "Success: 0x" <> proofHex
+       in Base16.encode proofBytes
 
 -- | Create a membership proof from a UTxO subset.
 --
@@ -212,7 +211,7 @@ createMembershipProofFromUTxO ::
   -- | Common Reference String (CRS) for the cryptographic proof
   [Point2] ->
   -- | Returns a string: "Success: 0x..." or "Error: ..."
-  Text
+  ByteString
 createMembershipProofFromUTxO subsetUTxO fullAcc crs = do
   -- Extract individual TxOut elements from the subset
   -- This matches how buildFromUTxO serializes each TxOut

hydra-tx/src/Hydra/Tx/Close.hs

@@ -2,7 +2,7 @@
 
 module Hydra.Tx.Close where
 
-import Hydra.Cardano.Api
+import Hydra.Cardano.Api hiding (utxo)
 import Hydra.Prelude
 
 import Hydra.Contract.Head qualified as Head
@@ -29,6 +29,7 @@ import Hydra.Tx.Accumulator qualified as Accumulator
 import Hydra.Tx.Crypto (toPlutusSignatures)
 import Hydra.Tx.Utils (IncrementalAction (..), findStateToken, mkHydraHeadV1TxName)
 import PlutusLedgerApi.V3 (toBuiltin)
+import PlutusTx.Builtins (bls12_381_G2_uncompress, toBuiltin)
 
 -- * Construction
 
@@ -92,7 +93,8 @@ closeTx scriptRegistry vk headId openVersion confirmedSnapshot startSlotNo (endS
 
   closeRedeemer =
     case confirmedSnapshot of
-      InitialSnapshot{} -> Head.CloseInitial
+      InitialSnapshot{} ->
+        Head.CloseInitial
       ConfirmedSnapshot{signatures, snapshot = Snapshot{version}} ->
         case incrementalAction of
           ToCommit utxo' ->
@@ -109,17 +111,38 @@ closeTx scriptRegistry vk headId openVersion confirmedSnapshot startSlotNo (endS
                   }
           ToDecommit utxo' ->
             if version == openVersion
-              then Head.CloseUnusedDec{signature = toPlutusSignatures signatures}
+              then
+                Head.CloseUnusedDec
+                  { signature = toPlutusSignatures signatures
+                  }
               else
                 Head.CloseUsedDec
                   { signature = toPlutusSignatures signatures
                   , alreadyDecommittedUTxOHash = toBuiltin $ hashUTxO utxo'
                   }
-          NoThing -> Head.CloseAny{signature = toPlutusSignatures signatures}
+          NoThing ->
+            Head.CloseAny
+              { signature = toPlutusSignatures signatures
+              }
 
   headOutputAfter =
     modifyTxOutDatum (const headDatumAfter) headOutputBefore
 
+  snapshot = getSnapshot confirmedSnapshot
+
+  proof =
+    let snapshotUTxO =
+          utxo snapshot
+            <> case closeRedeemer of
+              Head.CloseUsedInc{} ->
+                fromMaybe mempty (utxoToCommit snapshot)
+              Head.CloseUnusedDec{} ->
+                fromMaybe mempty (utxoToDecommit snapshot)
+              _ -> mempty
+     in bls12_381_G2_uncompress $
+          toBuiltin $
+            Accumulator.createMembershipProofFromUTxO @Tx snapshotUTxO (accumulator snapshot) Accumulator.defaultCRS
+
   headDatumAfter =
     mkTxOutDatumInline $
       Head.Closed
@@ -145,10 +168,10 @@ closeTx scriptRegistry vk headId openVersion confirmedSnapshot startSlotNo (endS
           , contesters = []
           , version = fromIntegral openVersion
           , accumulatorHash = toBuiltin closedAccumulatorHash
+          , proof
           }
    where
-    snapshot = getSnapshot confirmedSnapshot
-    closedAccumulatorHash = Accumulator.getAccumulatorHash $ accumulator snapshot
+    closedAccumulatorHash = Accumulator.getAccumulatorHash $ accumulator $ getSnapshot confirmedSnapshot
 
   contestationDeadline =
     addContestationPeriod (posixFromUTCTime utcTime) openContestationPeriod

hydra-tx/src/Hydra/Tx/Contest.hs

@@ -21,6 +21,7 @@ import Hydra.Tx.Utils (IncrementalAction (..), findStateToken, mkHydraHeadV1TxNa
 import PlutusLedgerApi.V1.Crypto qualified as Plutus
 import PlutusLedgerApi.V3 (toBuiltin)
 import PlutusLedgerApi.V3 qualified as Plutus
+import PlutusTx.Builtins (bls12_381_G2_uncompress)
 
 import Hydra.Plutus.Orphans ()
 
@@ -124,6 +125,19 @@ contestTx scriptRegistry vk headId contestationPeriod openVersion snapshot sig (
       then closedContestationDeadline
       else addContestationPeriod closedContestationDeadline onChainConstestationPeriod
 
+  proof =
+    let snapshotUTxO =
+          utxo
+            <> case contestRedeemer of
+              Head.ContestUsedInc{} ->
+                fromMaybe mempty utxoToCommit
+              Head.ContestUnusedDec{} ->
+                fromMaybe mempty utxoToDecommit
+              _ -> mempty
+     in bls12_381_G2_uncompress $
+          toBuiltin $
+            Accumulator.createMembershipProofFromUTxO @Tx snapshotUTxO accumulator Accumulator.defaultCRS
+
   headDatumAfter =
     mkTxOutDatumInline $
       Head.Closed
@@ -147,6 +161,7 @@ contestTx scriptRegistry vk headId contestationPeriod openVersion snapshot sig (
           , contesters = contester : closedContesters
           , version = toInteger openVersion
           , accumulatorHash = toBuiltin contestAccumulatorHash
+          , proof
           }
    where
     contestAccumulatorHash = Accumulator.getAccumulatorHash accumulator

hydra-tx/src/Hydra/Tx/Fanout.hs

@@ -4,13 +4,16 @@ import Hydra.Cardano.Api
 import Hydra.Prelude
 
 import Cardano.Api.UTxO qualified as UTxO
+import Cardano.Crypto.EllipticCurve.BLS12_381 (blsSerialize)
 import Hydra.Contract.Head qualified as Head
 import Hydra.Contract.HeadState qualified as Head
 import Hydra.Contract.MintAction (MintAction (..))
 import Hydra.Ledger.Cardano.Builder (burnTokens, unsafeBuildTransaction)
+import Hydra.Tx.Accumulator qualified as Accumulator
 import Hydra.Tx.HeadId (HeadId)
 import Hydra.Tx.ScriptRegistry (ScriptRegistry (..))
 import Hydra.Tx.Utils (findStateToken, headTokensFromValue, mkHydraHeadV1TxName)
+import PlutusTx.Builtins (bls12_381_G1_uncompress, bls12_381_G2_uncompress, toBuiltin)
 
 -- * Creation
 
@@ -43,18 +46,23 @@ fanoutTx scriptRegistry utxo utxoToCommit utxoToDecommit (headInput, headOutput)
       & setTxValidityLowerBound (TxValidityLowerBound $ deadlineSlotNo + 1)
       & setTxMetadata (TxMetadataInEra $ mkHydraHeadV1TxName "FanoutTx")
  where
+  crs = bls12_381_G1_uncompress . toBuiltin . blsSerialize <$> Accumulator.defaultCRS
+
   headWitness =
     BuildTxWith $
       ScriptWitness scriptWitnessInCtx $
         mkScriptReference headScriptRef Head.validatorScript InlineScriptDatum headRedeemer
+
   headScriptRef =
     fst (headReference scriptRegistry)
+
   headRedeemer =
     toScriptData $
       Head.Fanout
         { numberOfFanoutOutputs = fromIntegral $ UTxO.size utxo
         , numberOfCommitOutputs = fromIntegral $ length orderedTxOutsToCommit
         , numberOfDecommitOutputs = fromIntegral $ length orderedTxOutsToDecommit
+        , crs
         }
 
   headTokens =

hydra-tx/test/Hydra/Tx/Contract/FanOut.hs

@@ -23,7 +23,7 @@ import Hydra.Tx.Init (mkHeadOutput)
 import Hydra.Tx.IsTx (IsTx (hashUTxO))
 import Hydra.Tx.Party (Party, partyToChain, vkey)
 import Hydra.Tx.Utils (adaOnly, splitUTxO)
-import PlutusTx.Builtins (toBuiltin)
+import PlutusTx.Builtins (bls12_381_G2_uncompress, toBuiltin)
 import Test.Hydra.Tx.Fixture (slotLength, systemStart, testNetworkId, testPolicyId, testSeedInput)
 import Test.Hydra.Tx.Gen (genOutputFor, genScriptRegistry, genUTxOWithSimplifiedAddresses, genValue)
 import Test.Hydra.Tx.Mutation (Mutation (..), SomeMutation (..), changeMintedTokens)
@@ -81,6 +81,9 @@ healthyContestationDeadline =
 healthyFanoutSnapshotUTxO :: (UTxO, UTxO)
 healthyFanoutSnapshotUTxO = splitUTxO healthyFanoutUTxO
 
+accumulator :: Accumulator.HydraAccumulator
+accumulator = Accumulator.buildFromUTxO @Tx (uncurry (<>) healthyFanoutSnapshotUTxO)
+
 healthyFanoutDatum :: Head.State
 healthyFanoutDatum =
   Head.Closed
@@ -96,7 +99,13 @@ healthyFanoutDatum =
       , headId = toPlutusCurrencySymbol testPolicyId
       , contesters = []
       , version = 0
-      , accumulatorHash = toBuiltin $ Accumulator.getAccumulatorHash (Accumulator.buildFromUTxO (fst healthyFanoutSnapshotUTxO))
+      , accumulatorHash = toBuiltin $ Accumulator.getAccumulatorHash accumulator
+      , proof =
+          let snapshotUTxO =
+                uncurry (<>) healthyFanoutSnapshotUTxO
+           in bls12_381_G2_uncompress $
+                toBuiltin $
+                  Accumulator.createMembershipProofFromUTxO @Tx snapshotUTxO accumulator Accumulator.defaultCRS
       }
  where
   healthyContestationPeriodSeconds = 10