feat(host-contracts): add previous block hash to the hashes used to generate computed handles

Author: antoniupop

host-contracts/contracts/FHEVMExecutor.sol

@@ -674,7 +674,7 @@ contract FHEVMExecutor is UUPSUpgradeableEmptyProxy, FHEEvents, ACLOwnable {
 
         /// @dev It must not cast to same type.
         if (typeCt == toType) revert InvalidType();
-        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, Operators.cast, ct, toType, acl, block.chainid));
+        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, Operators.cast, ct, toType, acl, block.chainid, blockhash(block.number - 1)));
         result = _appendMetadataToPrehandle(result, toType);
         hcuLimit.checkHCUForCast(toType, ct, result, msg.sender);
         acl.allowTransient(result, msg.sender);
@@ -698,7 +698,7 @@ contract FHEVMExecutor is UUPSUpgradeableEmptyProxy, FHEEvents, ACLOwnable {
             (1 << uint8(FheType.Uint256));
 
         if ((1 << uint8(toType)) & supportedTypes == 0) revert UnsupportedType();
-        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, Operators.trivialEncrypt, pt, toType, acl, block.chainid));
+        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, Operators.trivialEncrypt, pt, toType, acl, block.chainid, blockhash(block.number - 1)));
         result = _appendMetadataToPrehandle(result, toType);
         hcuLimit.checkHCUForTrivialEncrypt(toType, result, msg.sender);
         acl.allowTransient(result, msg.sender);
@@ -815,7 +815,7 @@ contract FHEVMExecutor is UUPSUpgradeableEmptyProxy, FHEEvents, ACLOwnable {
 
     function _unaryOp(Operators op, bytes32 ct) internal virtual returns (bytes32 result) {
         if (!acl.isAllowed(ct, msg.sender)) revert ACLNotAllowed(ct, msg.sender);
-        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, ct, acl, block.chainid));
+        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, ct, acl, block.chainid, blockhash(block.number - 1)));
         FheType typeCt = _typeOf(ct);
         result = _appendMetadataToPrehandle(result, typeCt);
         acl.allowTransient(result, msg.sender);
@@ -839,7 +839,7 @@ contract FHEVMExecutor is UUPSUpgradeableEmptyProxy, FHEEvents, ACLOwnable {
             FheType lhsType = _typeOf(lhs);
             if (lhsType != rhsType) revert IncompatibleTypes();
         }
-        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, rhs, scalar, acl, block.chainid));
+        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, rhs, scalar, acl, block.chainid, blockhash(block.number - 1)));
         result = _appendMetadataToPrehandle(result, resultType);
         acl.allowTransient(result, msg.sender);
     }
@@ -862,7 +862,7 @@ contract FHEVMExecutor is UUPSUpgradeableEmptyProxy, FHEEvents, ACLOwnable {
         if (lhsType != FheType.Bool) revert UnsupportedType();
         if (middleType != rhsType) revert IncompatibleTypes();
 
-        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, middle, rhs, acl, block.chainid));
+        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, middle, rhs, acl, block.chainid, blockhash(block.number - 1)));
         result = _appendMetadataToPrehandle(result, middleType);
         acl.allowTransient(result, msg.sender);
     }

host-contracts/rust_bindings/src/fhevm_executor.rs

@@ -313,7 +313,7 @@ contract FHEVMExecutorTest is SupportedTypesConstants, Test {
         bytes32 handle,
         FheType resultType
     ) internal view returns (bytes32 result) {
-        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, handle, acl, block.chainid));
+        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, handle, acl, block.chainid, blockhash(block.number - 1)));
         result = _appendMetadataToPrehandle(resultType, result, block.chainid, HANDLE_VERSION);
     }
 
@@ -325,7 +325,7 @@ contract FHEVMExecutorTest is SupportedTypesConstants, Test {
         FheType resultType
     ) internal view returns (bytes32 result) {
         scalar = scalar & 0x01;
-        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, rhs, scalar, acl, block.chainid));
+        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, rhs, scalar, acl, block.chainid, blockhash(block.number - 1)));
         result = _appendMetadataToPrehandle(resultType, result, block.chainid, HANDLE_VERSION);
     }
 
@@ -337,7 +337,7 @@ contract FHEVMExecutorTest is SupportedTypesConstants, Test {
         FheType resultType
     ) internal view returns (bytes32 result) {
         scalar = scalar & 0x01;
-        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, rhs, scalar, acl, block.chainid));
+        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, rhs, scalar, acl, block.chainid, blockhash(block.number - 1)));
         result = _appendMetadataToPrehandle(resultType, result, block.chainid, HANDLE_VERSION);
     }
 
@@ -348,7 +348,7 @@ contract FHEVMExecutorTest is SupportedTypesConstants, Test {
         bytes32 rhs,
         FheType middleFheType
     ) internal view returns (bytes32 result) {
-        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, middle, rhs, acl, block.chainid));
+        result = keccak256(abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, op, lhs, middle, rhs, acl, block.chainid, blockhash(block.number - 1)));
         result = _appendMetadataToPrehandle(middleFheType, result, block.chainid, HANDLE_VERSION);
     }
 
@@ -1117,7 +1117,7 @@ contract FHEVMExecutorTest is SupportedTypesConstants, Test {
         address sender = address(123);
 
         bytes32 expectedResult = keccak256(
-            abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, FHEVMExecutor.Operators.trivialEncrypt, pt, FheType(fheType), acl, block.chainid)
+            abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, FHEVMExecutor.Operators.trivialEncrypt, pt, FheType(fheType), acl, block.chainid, blockhash(block.number - 1))
         );
         expectedResult = _appendMetadataToPrehandle(FheType(fheType), expectedResult, block.chainid, HANDLE_VERSION);
 
@@ -1143,7 +1143,7 @@ contract FHEVMExecutorTest is SupportedTypesConstants, Test {
         _approveHandleInACL(handle, sender);
 
         bytes32 expectedResult = keccak256(
-            abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, FHEVMExecutor.Operators.cast, handle, FheType(fheOutputType), acl, block.chainid)
+            abi.encodePacked(COMPUTATION_DOMAIN_SEPARATOR, FHEVMExecutor.Operators.cast, handle, FheType(fheOutputType), acl, block.chainid, blockhash(block.number - 1))
         );
 
         expectedResult = _appendMetadataToPrehandle(