MCMS predecessor and salt length check == 32

contracts/mcms/api/daml/MCMS/Crypto.daml

@@ -171,8 +171,10 @@ hashMetadataLeafNative meta =
 -- TIMELOCK HASH FUNCTIONS
 -- ===========================================================================
 
--- opId = keccak256(abi.encode(calls, predecessor, salt))
--- Uses length-prefixed encoding to prevent collision attacks
+-- opId = keccak256(calls, predecessor, salt)
+-- Every variable-length field is length-prefixed (not raw-concatenated), so the
+-- encoding is injective and immune to predecessor/salt boundary-shift collisions.
+-- predecessor and salt are additionally enforced to be 32 bytes at the call sites.
 hashTimelockOpId : [TimelockCall] -> BytesHex -> BytesHex -> BytesHex
 hashTimelockOpId calls predecessor salt =
   let
@@ -226,6 +228,14 @@ assertValidHex fieldName hex =
   assertMsg (fieldName <> ": invalid hex (must be even-length, 0-9a-fA-F only): " <> hex)
     (isValidHex hex)
 
+-- | Validate that a field is a well-formed 32-byte value (hex-encoded).
+-- Used for timelock predecessor and salt
+assertValidBytes32 : Text -> BytesHex -> Update ()
+assertValidBytes32 fieldName hex = do
+  assertValidHex fieldName hex
+  assertMsg ("mcms: " <> fieldName <> " must be 32 bytes, got " <> show (byteCount hex)) $
+    byteCount hex == 32
+
 -- ===========================================================================
 -- MERKLE PROOF VERIFICATION
 -- ===========================================================================

contracts/mcms/core/daml/MCMS/Main.daml

@@ -363,8 +363,8 @@ template MCMS
       controller submitter
       do
         -- 0. Validate BytesHex inputs
-        assertValidHex "predecessor" predecessor
-        assertValidHex "salt" salt
+        assertValidBytes32 "predecessor" predecessor
+        assertValidBytes32 "salt" salt
         forA_ calls $ \call -> assertValidHex "call.operationData" call.operationData
 
         now <- getTime
@@ -696,6 +696,8 @@ executeSelfDispatch mcms call =
           forA_ params.calls $ \c ->
             assertMsg ("mcms: function blocked: " <> c.targetInstanceAddress <> ":" <> c.functionName) $
               BlockedFunction c.targetInstanceAddress c.functionName `notElem` mcms.blockedFunctions
+          assertValidBytes32 "predecessor" params.predecessor
+          assertValidBytes32 "salt" params.salt
           let opId = hashTimelockOpId params.calls params.predecessor params.salt
           assertMsg "mcms: operation already scheduled" $
             not $ Map.member opId mcms.timelockTimestamps
@@ -757,7 +759,9 @@ scheduleBatchInternal now mcms rs calls predecessor salt delay = do
     assertMsg ("mcms: function blocked: " <> call.targetInstanceAddress <> ":" <> call.functionName) $
       BlockedFunction call.targetInstanceAddress call.functionName `notElem` mcms.blockedFunctions
 
-  -- 3. Compute opId
+  -- 3. Validate predecessor and salt are 32-byte values, then compute opId
+  assertValidBytes32 "predecessor" predecessor
+  assertValidBytes32 "salt" salt
   let opId = hashTimelockOpId calls predecessor salt
 
   -- 4. Check not already scheduled (on-chain duplicate prevention)

contracts/mcms/test/daml/MCMS/ExternalTargetTest.daml

@@ -108,7 +108,7 @@ externalScheduleOp = Op
   , nonce = 0
   , targetInstanceAddress = "mcms-daml-test@ccip_owner-9cefe94d"
   , functionName = "ScheduleBatch"
-  , operationData = "011b636f756e74657240636369705f6f776e65722d396365666539346409496e6372656d656e74000000200000000000000000000000000000000000000000000000000000000000000000000f65787465726e616c2d73616c742d310000000000000000"
+  , operationData = "011b636f756e74657240636369705f6f776e65722d396365666539346409496e6372656d656e740000002000000000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000065787465726e616c2d73616c742d310000000000000000"
   }
 
 externalScheduleMetadata : RootMetadata
@@ -121,11 +121,11 @@ externalScheduleMetadata = RootMetadata
   }
 
 externalScheduleRoot : Text
-externalScheduleRoot = "4f91344c80e695656fef97b4c58382b66ce1b984c3bcf7d94efcb0daafa4772c"
+externalScheduleRoot = "a5de111064a236613fc3434e6832f8bc0d0e12a912d412705bc1730cb72b108c"
 
 externalScheduleMetadataProof : [Text]
 externalScheduleMetadataProof =
-  [ "e0a871ad97f2400815079772600b3e09b04d0487822918cf15db61344bc396f4"
+  [ "5ac687c6c469d00fca89f3a6b2909416ddd500456cff668dd94bca2d621a1ccf"
   ]
 
 externalScheduleOpProof : [Text]
@@ -138,18 +138,18 @@ externalScheduleSignatures : [RawSignature]
 externalScheduleSignatures =
   [ RawSignature
       { publicKey = "04c170cfd2dfedf29d6dc68f57205d5b2a182dfbf0ae5fc4f6d9cb3382e6ab194e5e236469efad820ecceb3c474be2657747ea6d947fd79cb73f1834b45911cc2e"
-      , r = "12b1795146cdb8c6c2ddd50aff263094a206f589e6667e2f5ea2af34f194d505"
-      , s = "123ddca05b3ad0a94e1bbd48b9f6b801a18e9b5dd0788480af496d2c63cfc0a0"
+      , r = "365ad57001ca8a19812e13f58cf6dbdc48856860c6d4e18727e758d703179751"
+      , s = "24b35648bbb1917913b589a91317e44ebd61287156e815f4fb1de43e5e38358f"
       }
   , RawSignature
       { publicKey = "04be6d6382ad269cab52671739bb27d4b3ac087c46c7956324810dee6fa311ef8eb1065e376017fe4a8d3d5ee0e86f837f9bb69f22331c1828e5521765f2cdee31"
-      , r = "c8f3b29c9185437668a2cdca62792c7285caaec86e39f3edb8cd6b9beacdd4b8"
-      , s = "4d6fdde4f1d737a933dfe760d59a45d644633a4c7dc61ded9d4c1ecc2306e969"
+      , r = "cf4c3ae13e7d37a905b35519209b24e05cbf4ac8597f7b9f7fd18f6466ba2720"
+      , s = "227a13c64283758057023e7f3ed30a4518b818b4ebba224ceaf3373e8c9fc692"
       }
   ]
 
 externalScheduleSalt : Text
-externalScheduleSalt = "65787465726e616c2d73616c742d31"
+externalScheduleSalt = "000000000000000000000000000000000065787465726e616c2d73616c742d31"
 
 -- ===========================================================================
 -- BYPASSER EXTERNAL CALL TESTS