Merge pull request #20 from sCrypt-Inc/blockchain-lib

Finish blockchain lib
sCrypt-Inc · Mar 29, 2024 · 2dd2980 · 2dd2980
2 parents aac8fe3 + 833d5ac
commit 2dd2980
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Showing 4 changed files with 427 additions and 409 deletions.
diff --git a/src/blockchain.ts b/src/blockchain.ts
@@ -41,74 +41,64 @@ export class Blockchain extends SmartContractLib {
         )
     }
 
-    // Is txid the last transaction in a block
+    // Check if tx is the last within block using its merkle path.
     @method()
-    static lastTxInBlock(
+    static isLastTxInBlock(merkleProof: MerkleProof, depth: number): boolean {
+        let last = true
+
+        for (let i = 0; i < depth; i++) {
+            const node = merkleProof[i]
+
+            if (node.pos != MerklePath.INVALID_NODE) {
+                if (node.pos != MerklePath.LEFT_NODE) {
+                    last = false
+                }
+            }
+        }
+
+        return last
+    }
+
+    // Calculate a tx's index in a block from its merkle path.
+    @method()
+    static txIndex(
         txid: Sha256,
-        bh: BlockHeader,
         merkleProof: MerkleProof,
         depth: number
-    ): boolean {
-        let last = true
+    ): bigint {
         let root = txid
+        let sum = 0n
 
         for (let i = 0; i < depth; i++) {
             const node = merkleProof[i]
 
             if (node.pos != MerklePath.INVALID_NODE) {
-                // IF LAST ELEMENT:
-                // - A non-duplicate node cannot ever be on the right.
-                const isDuplicate = node.hash == root
-                if (!isDuplicate && node.pos == MerklePath.RIGHT_NODE) {
-                    last = false
+                if (node.pos == MerklePath.LEFT_NODE) {
+                    // Check if duplicate.
+                    if (root != node.hash) {
+                        sum += lshift(1n, BigInt(i))
+                    }
+                    root = Sha256(hash256(node.hash + root))
+                } else {
+                    root = Sha256(hash256(root + node.hash))
                 }
-
-                root = Sha256(
-                    node.pos == MerklePath.LEFT_NODE
-                        ? hash256(node.hash + root)
-                        : hash256(root + node.hash)
-                )
             }
         }
 
-        return last && root == bh.merkleRoot
+        return sum
     }
 
-    // TODO:
-    // The function below assumes there cannot be any duplicate nodes on the left-hand side,
-    // which is false.
-    //// Calculate a tx's index in a block from its merkle path.
-    //// Goes from top to bottom, the path basically encodes the index in binary form.
-    //// left/L means 1, and right/R 0: e.g., (L, R, L) denotes 101 in binary, and 5 in decimal
-    //@method()
-    //static txIndex(merkleProof: MerkleProof): bigint {
-    //    let sum = 0n
-
-    //    // traverse the path from top to bottom
-    //    for (let i = 0; i < MerklePath.DEPTH; i++) {
-    //        const node = merkleProof[Number(MerklePath.DEPTH) - i - 1]
-
-    //        if (node.pos != MerklePath.INVALID_NODE) {
-    //            sum *= 2n
-    //            if (node.pos == MerklePath.LEFT_NODE) {
-    //                sum++
-    //            }
-    //        }
-    //    }
-    //    return sum
-    //}
-
-    //// Get number of transactions in a block.
-    //@method()
-    //static blockTxCount(
-    //    bh: BlockHeader,
-    //    lastTxid: Sha256,
-    //    merkleProof: MerkleProof
-    //): bigint {
-    //    // Ensure this tx is indeed the last one.
-    //    assert(Blockchain.lastTxInBlock(lastTxid, bh, merkleProof))
-    //    return Blockchain.txIndex(merkleProof) + 1n
-    //}
+    // Get number of transactions in a block based using its last tx merkle path.
+    @method()
+    static blockTxCount(
+        lastTxid: Sha256,
+        merkleProof: MerkleProof,
+        depth: number
+    ): bigint {
+        // Ensure this tx is indeed the last one.
+        assert(Blockchain.isLastTxInBlock(merkleProof, depth))
+        return Blockchain.txIndex(lastTxid, merkleProof, depth) + 1n
+    }
 
     // Is block header valid with difficulty meeting target.
     @method()

diff --git a/tests/contracts/blockchainTest.ts b/tests/contracts/blockchainTest.ts
@@ -18,13 +18,8 @@ export class BlockchainTest extends SmartContract {
     }
 
     @method()
-    public testLastTxInBlock(
-        txid: Sha256,
-        bh: BlockHeader,
-        merkleProof: MerkleProof,
-        res: boolean
-    ) {
-        assert(Blockchain.lastTxInBlock(txid, bh, merkleProof, 32) == res)
+    public testLastTxInBlock(merkleProof: MerkleProof, res: boolean) {
+        assert(Blockchain.isLastTxInBlock(merkleProof, 32) == res)
     }
 
     @method()
@@ -51,21 +46,17 @@ export class BlockchainTest extends SmartContract {
         assert(Blockchain.blockHeight(bh, coinbaseTx, merkleProof, 32) == res)
     }
 
-    //@method()
-    //public testTxIndex(
-    //    merkleProof: MerkleProof,
-    //    res: bigint
-    //) {
-    //    assert(Blockchain.txIndex(merkleProof) == res)
-    //}
+    @method()
+    public testTxIndex(txid: Sha256, merkleProof: MerkleProof, res: bigint) {
+        assert(Blockchain.txIndex(txid, merkleProof, 32) == res)
+    }
 
-    //@method()
-    //public testBlockTxCount(
-    //    bh: BlockHeader,
-    //    lastTxId: Sha256,
-    //    merkleProof: MerkleProof,
-    //    res: bigint
-    //) {
-    //    assert(Blockchain.blockTxCount(bh, lastTxId, merkleProof) == res)
-    //}
+    @method()
+    public testBlockTxCount(
+        lastTxId: Sha256,
+        merkleProof: MerkleProof,
+        res: bigint
+    ) {
+        assert(Blockchain.blockTxCount(lastTxId, merkleProof, 32) == res)
+    }
 }