WitnessUtils library improvement

crates/evm/src/evm/system_contracts/foundry.toml

@@ -2,6 +2,7 @@
 src = "src"
 out = "out"
 libs = ["lib"]
+ffi = true
 # Following options strips the metadata from contracts, this is done to ensure a more stable compilation
 bytecode_hash = "none"
 cbor_metadata = false

crates/evm/src/evm/system_contracts/lib/WitnessUtils.sol

@@ -11,7 +11,6 @@ import "bitcoin-spv/solidity/contracts/BTCUtils.sol";
 library WitnessUtils {
     using BytesLib for bytes;
     using BTCUtils for bytes;
-    using SafeMath for uint256;
 
     function calculateWtxId(
         bytes4 version,
@@ -63,18 +62,18 @@ library WitnessUtils {
     /// @return          The length of the witness in bytes
     function determineWitnessLengthAt(bytes memory _witness, uint256 _at) internal pure returns (uint256) {
         uint256 _varIntDataLen;
-        uint256 _nWits;
+        uint256 _nStackItems;
 
-        (_varIntDataLen, _nWits) = BTCUtils.parseVarIntAt(_witness, _at);
+        (_varIntDataLen, _nStackItems) = BTCUtils.parseVarIntAt(_witness, _at);
         if (_varIntDataLen == BTCUtils.ERR_BAD_ARG) {
             return BTCUtils.ERR_BAD_ARG;
         }
 
         uint256 _itemLen;
         uint256 _offset = 1 + _varIntDataLen;
 
-        for (uint256 i = 0; i < _nWits; i++) {
-            (_varIntDataLen, _itemLen) = BTCUtils.parseVarIntAt(_witness, _offset);
+        for (uint256 i = 0; i < _nStackItems; i++) {
+            (_varIntDataLen, _itemLen) = BTCUtils.parseVarIntAt(_witness, _at + _offset);
             if (_itemLen == BTCUtils.ERR_BAD_ARG) {
                 return BTCUtils.ERR_BAD_ARG;
             }

crates/evm/src/evm/system_contracts/test/WitnessUtils.t.sol

@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.13;
+
+import {Test, console} from "forge-std/Test.sol";
+import "forge-std/console.sol";
+import "../lib/WitnessUtils.sol";
+
+contract WitnessUtilsTest is Test {
+    bytes4 version = hex"01000000";
+    bytes2 flag = hex"0001";
+    bytes vin = hex"01438afdb24e414d54cc4a17a95f3d40be90d23dfeeb07a48e9e782178efddd8890100000000fdffffff";
+    bytes vout = hex"020db9a60000000000160014b549d227c9edd758288112fe3573c1f85240166880a81201000000001976a914ae28f233464e6da03c052155119a413d13f3380188ac";
+    bytes witness = hex"024730440220200254b765f25126334b8de16ee4badf57315c047243942340c16cffd9b11196022074a9476633f093f229456ad904a9d97e26c271fc4f01d0501dec008e4aae71c2012102c37a3c5b21a5991d3d7b1e203be195be07104a1a19e5c2ed82329a56b4312130";
+    bytes w2 = hex"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";
+    bytes4 locktime = hex"00000000";
+    bytes32 wtxId = hex"ff63ed0cc02c85a7aef6510625b6897abe1b969293f5db2991804e23f2562df1";
+    bytes wExample = hex"06096af9822fdb33bbfb940c6e6ea3d182c36de9c428de5606dbb8f257b63a10b66f7e408fcf8ed73ce3c3abf2aa28d809ef64e1bc35146424d00e072631fe3a08749c3380609e8fcd080582e984c1b5026351016404031f73220a964e3d835c33a0be6ca70206c9044dbc1b2c04b3411e2a";
+    bytes badWitness1 = hex"06096af9822fdb33bbfb940c6e6ea3d182c36de9c428de5606dbb8f257b63a10b66f7e408fcf8ed73ce3c3abf2aa28d809ef64e1bc35146424d00e072631fe3a08749c3380609e8fcd080582e984c1b5026351016404031f73220a964e3d835c33a0be6ca70206c9044dbc1b2c04b3411e";
+    bytes badWitness2 = hex"06096af9822fdb33bbfb940c6e6ea3d182c36de9c428de5606dbb8f257b63a10b66f7e408fcf8ed73ce3c3abf2aa28d809ef64e1bc35146424d00e072631fe3a08749c3380609e8fcd080582e984c1b5026351016404031f73220a964e3d835c33a0be6ca70206c9044dbc1b2c04b3411e2a32";
+    bytes badWitness3 = hex"06096af9822fdb33bbfb940c6e6ea3d182c36de9c428de5606dbb8f257b63a10b66f7e408fcf8ed73ce3c3abf2aa28d809ef64e1bc35146424d00e072631fe3a08749c3380609e8fcd080582e984c1b5026351016404031f73220a964e3d835c33a0be6ca70206c9044dbc1b2c04b3411e";
+    bytes badArgWitness = hex"0101ff";
+    bytes badArgWitness2 = hex"0101ff01ff";
+    // Helper function to run Python script and get its output
+    function getRandomWitness() public returns (bytes memory) {
+        string[] memory inputs = new string[](2);
+        inputs[0] = "python3";
+        inputs[1] = "test/randomWitnessGenerator.py";
+
+        bytes memory result = vm.ffi(inputs);
+        return result;
+    }
+
+    function getRandomStackItem() public returns (bytes memory) {
+        string[] memory inputs = new string[](2);
+        inputs[0] = "python3";
+        inputs[1] = "test/randomStackItemGenerator.py";
+
+        bytes memory result = vm.ffi(inputs);
+        return result;
+    }
+
+    function calculateWtxIdMock(
+        bytes4 _version,
+        bytes2 _flag,
+        bytes calldata _vin,
+        bytes calldata _vout,
+        bytes calldata _witness,
+        bytes4 _locktime
+    ) public view returns(bytes32) {
+        return WitnessUtils.calculateWtxId(
+            _version, 
+            _flag, 
+            _vin, 
+            _vout, 
+            _witness, 
+            _locktime
+        );
+    }
+
+    function testCalculateWtxId() public view{
+        bytes32 testWtxId = WitnessUtilsTest(address(this)).calculateWtxIdMock(
+            version, 
+            flag, 
+            vin, 
+            vout, 
+            witness, 
+            locktime
+        );
+        assertEq(testWtxId, wtxId);
+    }
+
+    function testValidateWitnessSpecific() public view {
+        assert(WitnessUtils.validateWitness(wExample, 2));
+    }
+
+    function testDetermineWitnessLengthAt() public {
+        uint256 _at;
+        bytes memory randomWitness;
+        for(int i = 0; i < 10; i++){
+            bytes memory randomWits = getRandomWitness();
+            randomWitness = abi.encodePacked(randomWitness, randomWits);            
+            assertEq(randomWits.length, WitnessUtils.determineWitnessLengthAt(randomWitness, _at));
+            _at += randomWits.length;
+        }
+    }
+
+    function testDetermineWitnessLengthAtMiddle() public {
+        bytes memory firstRandomWitness = getRandomWitness();
+        bytes memory secondRandomWitness = getRandomWitness();
+        bytes memory thirdRandomWitness = getRandomWitness();
+        bytes memory fourthRandomWitness = getRandomWitness();
+
+        bytes memory randomWitness = abi.encodePacked(firstRandomWitness, secondRandomWitness, thirdRandomWitness, fourthRandomWitness);
+
+        assertEq(thirdRandomWitness.length, WitnessUtils.determineWitnessLengthAt(randomWitness, firstRandomWitness.length + secondRandomWitness.length));
+    }
+
+    // This is unusual because we are testing the determineWitnessLengthAt function to not work properly with a not proper witness. But we decided to keep it to increase the testing quality.
+    function testDetermineWitnessLengthAtError() public view {
+        assertNotEq(badWitness1.length, WitnessUtils.determineWitnessLengthAt(badWitness1, 0));
+    }
+
+    function testDetermineWitnessLengthAtError2() public view {
+        assertEq(WitnessUtils.determineWitnessLengthAt(badArgWitness, 2), BTCUtils.ERR_BAD_ARG);
+    }
+
+    function testFuzzValidateWitness(uint8 x) public {
+        vm.assume(x>0);
+        vm.assume(x<4);
+        bytes memory randomWitness;
+        for (uint i = 0; i < x; i++){
+            bytes memory randomWits = getRandomWitness();
+            randomWitness = abi.encodePacked(randomWitness, randomWits);
+        }
+        assert(WitnessUtils.validateWitness(randomWitness, uint256(x)));
+    }
+
+    function testValidateWitnessError1() public view {
+        assertFalse(WitnessUtils.validateWitness(badWitness1, 2));
+    }
+    function testValidateWitnessError2() public view {
+        assertFalse(WitnessUtils.validateWitness(badWitness2, 2));
+    }
+
+    function testFuzzExtractWitnessAtIndex(uint8 x) public {
+        vm.assume(x<10);
+
+        bytes[] memory randomWitsArray = new bytes[](10);
+        bytes memory randomWitness;
+
+        for(uint i = 0; i < 10; i++){
+            bytes memory randomWits = getRandomWitness();
+            randomWitsArray[i] = randomWits;
+            randomWitness = abi.encodePacked(randomWitness, randomWits);            
+        }
+
+        assertEq(randomWitsArray[x], WitnessUtils.extractWitnessAtIndex(randomWitness, x));
+    }
+
+    function testFuzzExtractItemFromWitness(uint8 x) public {
+        vm.assume(x<9);
+
+        bytes memory nStackItems = hex"09";
+        bytes[] memory randomStackItemArray = new bytes[](9);
+        bytes memory randomWits;
+        randomWits = abi.encodePacked(nStackItems, randomWits);
+
+        for(uint i = 0; i < 9; i++){
+            bytes memory randomStackItem = getRandomStackItem();
+            randomStackItemArray[i] = randomStackItem;
+            randomWits = abi.encodePacked(randomWits, randomStackItem);            
+        }
+
+        assertEq(randomStackItemArray[x], WitnessUtils.extractItemFromWitness(randomWits, x));
+    } 
+}
+
+
+
+
+
+

crates/evm/src/evm/system_contracts/test/randomStackItemGenerator.py

@@ -0,0 +1,26 @@
+import random
+
+def random_hex_byte(l, r):
+    assert(l >= 0)
+    assert(r <= 255)
+    # Generate a random integer between l and r
+    random_int = random.randint(l, r)
+    # Convert the integer to a hexadecimal string and remove the '0x' prefix
+    hex_value = hex(random_int)[2:]
+    # Ensure the hex value has two digits
+    if len(hex_value) == 1:
+        hex_value = '0' + hex_value
+    return hex_value
+
+stackItem = ""
+stackItemLength = random_hex_byte(0, 16)
+stackItem += stackItemLength
+for m in range(int(stackItemLength, 16)):
+    randombyte = random_hex_byte(0, 255)
+    stackItem += randombyte
+print(stackItem)
+
+
+
+
+

crates/evm/src/evm/system_contracts/test/randomWitnessGenerator.py

@@ -0,0 +1,29 @@
+import random
+
+def random_hex_byte(l, r):
+    assert(l >= 0)
+    assert(r <= 255)
+    # Generate a random integer between l and r
+    random_int = random.randint(l, r)
+    # Convert the integer to a hexadecimal string and remove the '0x' prefix
+    hex_value = hex(random_int)[2:]
+    # Ensure the hex value has two digits
+    if len(hex_value) == 1:
+        hex_value = '0' + hex_value
+    return hex_value
+
+witness = ""
+nStackItems = random_hex_byte(0, 8)
+witness += nStackItems
+for k in range(int(nStackItems, 16)):
+    stackItemLength = random_hex_byte(0, 16)
+    witness += stackItemLength
+    for m in range(int(stackItemLength, 16)):
+        randombyte = random_hex_byte(0, 255)
+        witness += randombyte
+print(witness)
+
+
+
+
+