Merge pull request #6169 from onflow/gregor/random-source-size

[EVM] Extend random source size

fvm/environment/history_random_source_provider.go

@@ -85,7 +85,7 @@ func NewRandomSourceHistoryProvider(
 	return NewForbiddenRandomSourceHistoryProvider()
 }
 
-const randomSourceHistoryLen = 32
+const RandomSourceHistoryLength = 32
 
 func (b *historySourceProvider) RandomSourceHistory() ([]byte, error) {
 	defer b.tracer.StartExtensiveTracingChildSpan(
@@ -104,7 +104,7 @@ func (b *historySourceProvider) RandomSourceHistory() ([]byte, error) {
 			"get random source for block randomSource failed: %w", err))
 	}
 
-	// A method that derives `randomSourceHistoryLen` bytes from `source` must:
+	// A method that derives `RandomSourceHistoryLength` bytes from `source` must:
 	//  - extract and expand the entropy in `source`
 	//  - output must be independent than the expanded bytes used for Cadence's `random` function
 	//
@@ -118,7 +118,7 @@ func (b *historySourceProvider) RandomSourceHistory() ([]byte, error) {
 		return nil, fmt.Errorf("failed to create a PRG from source: %w", err)
 	}
 
-	historySource := make([]byte, randomSourceHistoryLen)
+	historySource := make([]byte, RandomSourceHistoryLength)
 	csprg.Read(historySource)
 
 	return historySource, nil

fvm/evm/evm_test.go

@@ -23,6 +23,7 @@ import (
 	"github.com/onflow/flow-go/engine/execution/testutil"
 	"github.com/onflow/flow-go/fvm"
 	"github.com/onflow/flow-go/fvm/crypto"
+	"github.com/onflow/flow-go/fvm/environment"
 	envMock "github.com/onflow/flow-go/fvm/environment/mock"
 	"github.com/onflow/flow-go/fvm/evm"
 	"github.com/onflow/flow-go/fvm/evm/emulator"
@@ -2098,7 +2099,8 @@ func TestCadenceArch(t *testing.T) {
 				testAccount *EOATestAccount,
 			) {
 				entropy := []byte{13, 37}
-				source := []byte{91, 161, 206, 171, 100, 17, 141, 44} // coresponding out to the above entropy
+				// coresponding out to the above entropy
+				source := []byte{0x5b, 0xa1, 0xce, 0xab, 0x64, 0x11, 0x8d, 0x2c, 0xd8, 0xae, 0x8c, 0xbb, 0xf7, 0x50, 0x5e, 0xf5, 0xdf, 0xad, 0xfc, 0xf7, 0x2d, 0x3a, 0x46, 0x78, 0xd5, 0xe5, 0x1d, 0xb7, 0xf2, 0xb8, 0xe5, 0xd6}
 
 				// we must record a new heartbeat with a fixed block, we manually execute a transaction to do so,
 				// since doing this automatically would require a block computer and whole execution setup
@@ -2175,9 +2177,10 @@ func TestCadenceArch(t *testing.T) {
 				require.NoError(t, err)
 				require.NoError(t, output.Err)
 
-				res := make([]byte, 8)
+				res := make([]byte, environment.RandomSourceHistoryLength)
 				vals := output.Value.(cadence.Array).Values
-				vals = vals[len(vals)-8:] // only last 8 bytes is the value
+				require.Len(t, vals, environment.RandomSourceHistoryLength)
+
 				for i := range res {
 					res[i] = byte(vals[i].(cadence.UInt8))
 				}

fvm/evm/handler/precompiles.go

@@ -42,8 +42,8 @@ func blockHeightProvider(backend types.Backend) func() (uint64, error) {
 
 const RandomSourceTypeValueFieldName = "value"
 
-func randomSourceProvider(contractAddress flow.Address, backend types.Backend) func(uint64) (uint64, error) {
-	return func(blockHeight uint64) (uint64, error) {
+func randomSourceProvider(contractAddress flow.Address, backend types.Backend) func(uint64) ([]byte, error) {
+	return func(blockHeight uint64) ([]byte, error) {
 		value, err := backend.Invoke(
 			environment.ContractFunctionSpec{
 				AddressFromChain: func(_ flow.Chain) flow.Address {
@@ -63,21 +63,21 @@ func randomSourceProvider(contractAddress flow.Address, backend types.Backend) f
 			if types.IsAFatalError(err) || types.IsABackendError(err) {
 				panic(err)
 			}
-			return 0, err
+			return nil, err
 		}
 
 		data, ok := value.(cadence.Struct)
 		if !ok {
-			return 0, fmt.Errorf("invalid output data received from getRandomSource")
+			return nil, fmt.Errorf("invalid output data received from getRandomSource")
 		}
 
 		cadenceArray := cadence.SearchFieldByName(data, RandomSourceTypeValueFieldName).(cadence.Array)
-		source := make([]byte, 8)
+		source := make([]byte, environment.RandomSourceHistoryLength)
 		for i := range source {
 			source[i] = byte(cadenceArray.Values[i].(cadence.UInt8))
 		}
 
-		return binary.BigEndian.Uint64(source), nil
+		return source, nil
 	}
 }
 

fvm/evm/precompiles/arch.go

@@ -45,7 +45,7 @@ func ArchContract(
 	address types.Address,
 	heightProvider func() (uint64, error),
 	proofVer func(*types.COAOwnershipProofInContext) (bool, error),
-	randomSourceProvider func(uint64) (uint64, error),
+	randomSourceProvider func(uint64) ([]byte, error),
 	revertibleRandomGenerator func() (uint64, error),
 ) types.PrecompiledContract {
 	return MultiFunctionPrecompiledContract(
@@ -139,7 +139,7 @@ func (f *proofVerifier) Run(input []byte) ([]byte, error) {
 var _ Function = &randomnessSource{}
 
 type randomnessSource struct {
-	randomSourceProvider func(uint64) (uint64, error)
+	randomSourceProvider func(uint64) ([]byte, error)
 }
 
 func (r *randomnessSource) FunctionSelector() FunctionSelector {
@@ -160,8 +160,8 @@ func (r *randomnessSource) Run(input []byte) ([]byte, error) {
 		return nil, err
 	}
 
-	buf := make([]byte, EncodedUint64Size)
-	err = EncodeUint64(rand, buf, 0)
+	buf := make([]byte, EncodedBytes32Size)
+	err = EncodeBytes32(rand, buf, 0)
 	if err != nil {
 		return nil, err
 	}

fvm/evm/precompiles/arch_test.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/stretchr/testify/require"
 
+	"github.com/onflow/flow-go/fvm/environment"
 	"github.com/onflow/flow-go/fvm/evm/precompiles"
 	"github.com/onflow/flow-go/fvm/evm/testutils"
 	"github.com/onflow/flow-go/fvm/evm/types"
@@ -41,12 +42,15 @@ func TestArchContract(t *testing.T) {
 
 	t.Run("test get random source", func(t *testing.T) {
 		address := testutils.RandomAddress(t)
-		rand := uint64(1337)
+		rand := make([]byte, environment.RandomSourceHistoryLength)
+		err := precompiles.EncodeBytes32([]byte{13, 23}, rand, 0)
+		require.NoError(t, err)
+
 		pc := precompiles.ArchContract(
 			address,
 			nil,
 			nil,
-			func(u uint64) (uint64, error) {
+			func(u uint64) ([]byte, error) {
 				return rand, nil
 			},
 			nil,
@@ -61,9 +65,10 @@ func TestArchContract(t *testing.T) {
 		require.Equal(t, precompiles.RandomSourceGas, pc.RequiredGas(input))
 
 		ret, err := pc.Run(input)
+		require.Len(t, ret, environment.RandomSourceHistoryLength)
 		require.NoError(t, err)
 
-		resultRand, err := precompiles.ReadUint64(ret, 0)
+		resultRand, err := precompiles.ReadBytes32(ret, 0)
 		require.NoError(t, err)
 		require.Equal(t, rand, resultRand)
 	})

fvm/evm/testutils/contracts/test.sol

@@ -64,10 +64,10 @@ contract Storage {
        revert MyCustomError(5, "Value is too low");
     }
 
-    function verifyArchCallToRandomSource(uint64 height) public view returns (uint64) {
+    function verifyArchCallToRandomSource(uint64 height) public view returns (bytes32) {
         (bool ok, bytes memory data) = cadenceArch.staticcall(abi.encodeWithSignature("getRandomSource(uint64)", height));
         require(ok, "unsuccessful call to arch ");
-        uint64 output = abi.decode(data, (uint64));
+        bytes32 output = abi.decode(data, (bytes32));
         return output;
     }
 

fvm/evm/testutils/contracts/test_abi.json

@@ -226,9 +226,9 @@
 		"name": "verifyArchCallToRandomSource",
 		"outputs": [
 			{
-				"internalType": "uint64",
+				"internalType": "bytes32",
 				"name": "",
-				"type": "uint64"
+				"type": "bytes32"
 			}
 		],
 		"stateMutability": "view",