ecdsa-node-project

client/package.json

@@ -10,6 +10,7 @@
   },
   "dependencies": {
     "axios": "^0.27.2",
+    "ethereum-cryptography": "^2.1.3",
     "react": "^18.2.0",
     "react-dom": "^18.2.0"
   },

client/src/App.jsx

@@ -6,6 +6,7 @@ import { useState } from "react";
 function App() {
   const [balance, setBalance] = useState(0);
   const [address, setAddress] = useState("");
+  const [privateKey, setPrivateKey] = useState("");
 
   return (
     <div className="app">
@@ -14,8 +15,14 @@ function App() {
         setBalance={setBalance}
         address={address}
         setAddress={setAddress}
+        privateKey={privateKey}
+        setPrivateKey={setPrivateKey}
+      />
+      <Transfer
+      setBalance={setBalance}
+      address={address} 
+      privateKey={privateKey}
       />
-      <Transfer setBalance={setBalance} address={address} />
     </div>
   );
 }

client/src/Transfer.jsx

@@ -1,23 +1,44 @@
-import { useState } from "react";
+import React, { useState } from "react";
+import { keccak_256 } from "@noble/hashes/sha3";
+import { secp256k1 } from '@noble/curves/secp256k1';
+import { bytesToHex, utf8ToBytes } from "@noble/hashes/utils";
 import server from "./server";
 
-function Transfer({ address, setBalance }) {
+function Transfer({ address, setBalance, privateKey }) {
+
   const [sendAmount, setSendAmount] = useState("");
   const [recipient, setRecipient] = useState("");
-
+  
   const setValue = (setter) => (evt) => setter(evt.target.value);
 
-  async function transfer(evt) {
+  const hashMessage = (message) => {
+    const bytes = utf8ToBytes(message);
+    const hash = keccak_256(bytes);
+    return hash;
+  };
+
+  const signMessage = (message, privateKey) => {
+    const signed = secp256k1.sign(hashMessage(message), privateKey);
+    return signed;
+  };
+
+  const jsonReplacer = (key, value) => typeof value === "bigint" ? value.toString() : value;
+
+  async function transfer (evt) {
     evt.preventDefault();
 
+    const senderSignature = signMessage("transfer", privateKey);
+
     try {
       const {
         data: { balance },
       } = await server.post(`send`, {
         sender: address,
         amount: parseInt(sendAmount),
         recipient,
+        signature: JSON.stringify(senderSignature, jsonReplacer)
       });
+
       setBalance(balance);
     } catch (ex) {
       alert(ex.response.data.message);
@@ -33,22 +54,26 @@ function Transfer({ address, setBalance }) {
         <input
           placeholder="1, 2, 3..."
           value={sendAmount}
-          onChange={setValue(setSendAmount)}
+          onChange={setValue(setSendAmount)}  
         ></input>
       </label>
 
       <label>
         Recipient
         <input
-          placeholder="Type an address, for example: 0x2"
+          placeholder="Type in a public key..."
           value={recipient}
-          onChange={setValue(setRecipient)}
+          onChange={setValue(setRecipient)} 
         ></input>
       </label>
 
-      <input type="submit" className="button" value="Transfer" />
+      <input 
+      type="submit" 
+      className="button" 
+      value="Transfer" />
     </form>
   );
 }
 
+
 export default Transfer;

client/src/Wallet.jsx

@@ -1,31 +1,49 @@
 import server from "./server";
+import { secp256k1 } from "@noble/curves/secp256k1";
+import { bytesToHex } from "@noble/hashes/utils";
 
-function Wallet({ address, setAddress, balance, setBalance }) {
+
+function Wallet({ address, setAddress, balance, setBalance, privateKey, setPrivateKey }) {
+
   async function onChange(evt) {
-    const address = evt.target.value;
+
+    const privateKey = evt.target.value;
+    setPrivateKey(privateKey);
+
+    const address = bytesToHex(secp256k1.getPublicKey(privateKey));
     setAddress(address);
-    if (address) {
-      const {
-        data: { balance },
-      } = await server.get(`balance/${address}`);
-      setBalance(balance);
-    } else {
-      setBalance(0);
-    }
+
+if (address) {
+  const {
+    data: { balance },
+  } = await server.get(`balance/${address}`);
+  setBalance(balance);
+} else {
+  setBalance(0);
   }
+}
 
   return (
     <div className="container wallet">
       <h1>Your Wallet</h1>
 
       <label>
-        Wallet Address
-        <input placeholder="Type an address, for example: 0x1" value={address} onChange={onChange}></input>
+        Private Key
+        <input 
+        placeholder="Type in a private key..." 
+        value={privateKey} 
+        onChange={onChange}
+        ></input>
       </label>
 
+      <div>
+        Public Key: {address ? 
+        address.slice(0, 10) + "..." + address.slice(-10) :
+         "Invalid address"} 
+      </div>
+
       <div className="balance">Balance: {balance}</div>
     </div>
   );
 }
-
-export default Wallet;
+ export default Wallet;

server/index.js

@@ -1,38 +1,46 @@
 const express = require("express");
 const app = express();
 const cors = require("cors");
+const { verify } = require("./verification");
 const port = 3042;
 
 app.use(cors());
 app.use(express.json());
 
 const balances = {
-  "0x1": 100,
-  "0x2": 50,
-  "0x3": 75,
+/*public key:*/ "03c781cf2662714a11a3a9f98654d09abf35b59bb29952cf35f55088ce27166dba": 100, // Private Key: 3ae0ffa9b45dcf48baba0c45eb4f4dc3b6d7f4ed8e8d38548409c33d851d3734
+/*public key:*/ "0226afe000841b07c5f988abdb85f069d969697f7e576f9ba3217f75086d9b906d": 50 , // Private Key: 328fa7d1cb0ff6fd9e3e86a217f467d17e42aa3125b6c76ca18c0ca8ea07b5d3
+/*public key:*/ "020e8767c081c4c37b88a3bee1d0a726f88a5530ea8f8a63221b8e34e7066b0e01": 75 , // Private Key: 214f36fd9ccb8c1cff2665d4f808a0d2227efbb6a7c3c3ac935bbad8f2ba75d0
 };
 
 app.get("/balance/:address", (req, res) => {
   const { address } = req.params;
   const balance = balances[address] || 0;
+        console.log(`Address: ${address}, Balance: ${balance}`);
   res.send({ balance });
 });
 
-app.post("/send", (req, res) => {
-  const { sender, recipient, amount } = req.body;
+app.post("/send", async (req, res) => { 
+  const { sender, recipient, amount, signature } = req.body;  
+
 
-  setInitialBalance(sender);
-  setInitialBalance(recipient);
+if (!verify(signature, "transfer", sender)) {
+  return res.status(400).send({ message: "You are not the account owner!" });
+}
 
-  if (balances[sender] < amount) {
-    res.status(400).send({ message: "Not enough funds!" });
-  } else {
-    balances[sender] -= amount;
-    balances[recipient] += amount;
-    res.send({ balance: balances[sender] });
-  }
+setInitialBalance(sender);
+setInitialBalance(recipient);
+
+if (balances[sender] < amount) {
+  return res.status(400).send({ message: "Not enough funds!" });
+}
+  balances[sender] -= amount;
+  balances[recipient] += amount;
+  return res.send({ balance: balances[sender] });
+
 });
 
+
 app.listen(port, () => {
   console.log(`Listening on port ${port}!`);
 });