Use Merkle root hash in proof-of-work

block.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"bytes"
-	"crypto/sha256"
 	"encoding/gob"
 	"log"
 	"time"
@@ -36,15 +35,14 @@ func NewGenesisBlock(coinbase *Transaction) *Block {
 
 // HashTransactions returns a hash of the transactions in the block
 func (b *Block) HashTransactions() []byte {
-	var txHashes [][]byte
-	var txHash [32]byte
+	var transactions [][]byte
 
 	for _, tx := range b.Transactions {
-		txHashes = append(txHashes, tx.Hash())
+		transactions = append(transactions, tx.Serialize())
 	}
-	txHash = sha256.Sum256(bytes.Join(txHashes, []byte{}))
+	mTree := NewMerkleTree(transactions)
 
-	return txHash[:]
+	return mTree.RootNode.Data
 }
 
 // Serialize serializes the block