feat: allow verifying an ordinal transfer

src/BtcTxVerifier.sol

@@ -37,7 +37,7 @@ contract BtcTxVerifier is IBtcTxVerifier {
         bytes32 blockHash = mirror.getBlockHash(blockNum);
 
         if(
-            !BtcProof.validateScriptMatch(
+            !BtcProof.validateExactOut(
                 blockHash,
                 inclusionProof,
                 txOutIx,

src/library/BtcProof.sol

@@ -10,6 +10,9 @@ error AmountMismatch(uint256 txoSats, uint256 expected);
 error TxIDMismatch(bytes32 rawTxId, bytes32 txProofId);
 error BlockHashMismatch(bytes32 blockHeader, bytes32 givenBlockHash);
 
+error InvalidTxInHash(uint256 expected, uint256 actual);
+error InvalidTxInIndex(uint32 expected, uint32 actual);
+
 // BtcProof provides functions to prove things about Bitcoin transactions.
 // Verifies merkle inclusion proofs, transaction IDs, and payment details.
 library BtcProof {
@@ -27,7 +30,7 @@ library BtcProof {
      *
      * Always returns true or reverts with a descriptive reason.
      */
-    function validateScriptMatch(
+    function validateExactOut(
         bytes32 blockHash,
         BtcTxProof calldata txProof,
         uint256 txOutIx,
@@ -68,6 +71,70 @@ library BtcProof {
         return true;
     }
 
+    /**
+     * @dev Validates that a given transfer of ordinal(s) under a given block hash..
+     *
+     * This verifies all of the following:
+     * 1. Raw transaction contains a specific input (at index 0) that pays more than X to specific output (at index 0).
+     * 2. Raw transaction hashes to the given transaction ID.
+     * 3. Transaction ID appears under transaction root (Merkle proof).
+     * 4. Transaction root is part of the block header.
+     * 5. Block header hashes to a given block hash.
+     *
+     * The caller must separately verify that the block hash is in the chain.
+     *
+     * Always returns true or reverts with a descriptive reason.
+     */
+    function validateOrdinalTransfer(
+        bytes32 blockHash,
+        BtcTxProof calldata txProof,
+        uint256 txInId,
+        uint32 txInPrevTxIndex,
+        bytes calldata outputScript,
+        uint256 satoshisExpected
+    ) internal pure returns (bool) {
+        // 5. Block header to block hash
+
+        bytes32 blockHeaderBlockHash = getBlockHash(txProof.blockHeader);
+        if (blockHeaderBlockHash != blockHash) revert BlockHashMismatch(blockHeaderBlockHash, blockHash);
+
+        // 4. and 3. Transaction ID included in block
+        bytes32 blockTxRoot = getBlockTxMerkleRoot(txProof.blockHeader);
+        bytes32 txRoot = getTxMerkleRoot(
+            txProof.txId,
+            txProof.txIndex,
+            txProof.txMerkleProof
+        );
+        if (blockTxRoot != txRoot) revert TxMerkleRootMismatch(blockTxRoot, txRoot);
+
+        // 2. Raw transaction to TxID
+        bytes32 rawTxId = getTxID(txProof.rawTx);
+        if (rawTxId != txProof.txId) revert TxIDMismatch(rawTxId, txProof.txId);
+
+        // 1. Finally, validate raw transaction correctly transfers the ordinal(s).
+        // Parse transaction
+        BitcoinTx memory parsedTx = parseBitcoinTx(txProof.rawTx);
+        BitcoinTxIn memory txInput = parsedTx.inputs[0];
+        // Check if correct input transaction is used.
+        if (txInId != txInput.prevTxID) revert InvalidTxInHash(txInId, txInput.prevTxID);
+        // Check if correct index of that transaction is used.
+        if (txInPrevTxIndex == txInput.prevTxIndex) revert InvalidTxInIndex(txInPrevTxIndex, txInput.prevTxIndex);
+
+        BitcoinTxOut memory txo = parsedTx.outputs[0];
+        // if the length are less than 32, then use bytes32 to compare.
+        if  (txo.script.length <= 32 && outputScript.length <= 32) {
+            if (bytes32(txo.script) != bytes32(outputScript)) revert ScriptMismatch(txo.script, outputScript);
+        } else {
+            if (keccak256(txo.script) != keccak256(outputScript)) revert ScriptMismatch(txo.script, outputScript);
+        }
+        // We allow for sending more because of the dust limit which may cause problems.
+        if (txo.valueSats < satoshisExpected) revert AmountMismatch(txo.valueSats, satoshisExpected);
+
+        // We've verified that blockHash contains a transaction with correct script
+        // that sends at least satoshisExpected to the given hash.
+        return true;
+    }
+
     /**
      * @dev Compute a block hash given a block header.
      */

test/BtcProof.t.sol

@@ -6,14 +6,14 @@ import "forge-std/Test.sol";
 import { BtcProof, BtcTxProof, BitcoinTx, TxMerkleRootMismatch, ScriptMismatch, AmountMismatch, TxIDMismatch, BlockHashMismatch } from "../src/library/BtcProof.sol";
 
 contract MockBtcProof {
-    function validateScriptMatch(
+    function validateExactOut(
         bytes32 blockHash,
         BtcTxProof calldata txProof,
         uint256 txOutIx,
         bytes calldata outputScript,
         uint256 satoshisExpected
     ) external pure returns (bool) {
-        return BtcProof.validateScriptMatch(blockHash, txProof, txOutIx, outputScript, satoshisExpected);
+        return BtcProof.validateExactOut(blockHash, txProof, txOutIx, outputScript, satoshisExpected);
     }
 
     function getBlockHash(bytes calldata blockHeader)
@@ -301,7 +301,7 @@ contract BtcProofTest is DSTest {
         bytes memory destScript = hex"a914ae2f3d4b06579b62574d6178c10c882b9150374087";
 
         // Should succeed
-        BtcProofUtils.validateScriptMatch(
+        BtcProofUtils.validateExactOut(
             blockHash736000,
             BtcTxProof(header736000, txId736, 1, txProof736, tx736),
             0,
@@ -311,7 +311,7 @@ contract BtcProofTest is DSTest {
 
         // Make each argument invalid, one at a time.
         vm.expectRevert(abi.encodeWithSelector(BlockHashMismatch.selector, 0x00000000000000000002d52d9816a419b45f1f0efe9a9df4f7b64161e508323d, 0x00000000000000000000135a8473d7d3a3b091c928246c65ce2a396dd2a5ca9a));
-        BtcProofUtils.validateScriptMatch(
+        BtcProofUtils.validateExactOut(
             blockHash717695,
             BtcTxProof(header736000, txId736, 1, txProof736, tx736),
             0,
@@ -321,7 +321,7 @@ contract BtcProofTest is DSTest {
 
         // - Bad tx proof (doesn't match root)
         vm.expectRevert(abi.encodeWithSelector(TxMerkleRootMismatch.selector, 0xf8aec519bcd878c9713dc8153a72fd62e3667c5ade70d8d0415584b8528d79ca, 0x31b669b35884e22c31b286ed8949007609db6cb50afe8b6e6e649e62cc24e19c));
-        BtcProofUtils.validateScriptMatch(
+        BtcProofUtils.validateExactOut(
             blockHash717695,
             BtcTxProof(headerGood, txId736, 1, txProof736, tx736),
             0,
@@ -331,7 +331,7 @@ contract BtcProofTest is DSTest {
 
         // - Wrong tx index
         vm.expectRevert(abi.encodeWithSelector(TxMerkleRootMismatch.selector, 0x31b669b35884e22c31b286ed8949007609db6cb50afe8b6e6e649e62cc24e19c, 0x28ce7a513419e3d298d4cac4ce4e7b2ede283c56f4faf3d99801bc3585b29387));
-        BtcProofUtils.validateScriptMatch(
+        BtcProofUtils.validateExactOut(
             blockHash736000,
             BtcTxProof(header736000, txId736, 2, txProof736, tx736),
             0,
@@ -341,7 +341,7 @@ contract BtcProofTest is DSTest {
 
         // - Wrong tx output index
         vm.expectRevert(abi.encodeWithSelector(ScriptMismatch.selector, hex"a91415ecf89e95eb07fbc351b3f7f4c54406f7ee5c1087", hex"a914ae2f3d4b06579b62574d6178c10c882b9150374087"));
-        BtcProofUtils.validateScriptMatch(
+        BtcProofUtils.validateExactOut(
             blockHash736000,
             BtcTxProof(header736000, txId736, 1, txProof736, tx736),
             1,
@@ -351,7 +351,7 @@ contract BtcProofTest is DSTest {
 
         // - Wrong dest script hash
         vm.expectRevert(abi.encodeWithSelector(ScriptMismatch.selector, destScript, hex"abcd"));
-        BtcProofUtils.validateScriptMatch(
+        BtcProofUtils.validateExactOut(
             blockHash736000,
             BtcTxProof(header736000, txId736, 1, txProof736, tx736),
             0,
@@ -361,7 +361,7 @@ contract BtcProofTest is DSTest {
 
         // - Wrong amount, off by one satoshi
         vm.expectRevert(abi.encodeWithSelector(AmountMismatch.selector, 25200000, 25200001));
-        BtcProofUtils.validateScriptMatch(
+        BtcProofUtils.validateExactOut(
             blockHash736000,
             BtcTxProof(header736000, txId736, 1, txProof736, tx736),
             0,