diff --git a/backend/contracts/MyContract.sol b/backend/contracts/MyContract.sol
index cf1fec5..e50c519 100644
--- a/backend/contracts/MyContract.sol
+++ b/backend/contracts/MyContract.sol
@@ -1,27 +1,18 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.0;
 
-contract MyContract {
-    address public owner;
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
+
+contract MyContract is Ownable, ReentrancyGuard {
     uint256 public price;
     
     event Purchase(address buyer, uint256 amount);
 
     constructor() {
-        owner = msg.sender;
         price = 0.01 ether; // Начальная цена 0.01 ETH
     }
 
-    modifier onlyOwner() {
-        require(msg.sender == owner, "Only owner can call this function");
-        _;
-    }
-
-    function setOwner(address newOwner) public onlyOwner {
-        require(newOwner != address(0), "New owner cannot be zero address");
-        owner = newOwner;
-    }
-
     function setPrice(uint256 newPrice) public onlyOwner {
         price = newPrice;
     }
@@ -30,12 +21,13 @@ contract MyContract {
         return price;
     }
 
-    function purchase(uint256 amount) public payable {
+    function purchase(uint256 amount) public payable nonReentrant {
         require(msg.value == price * amount, "Incorrect payment amount");
         emit Purchase(msg.sender, amount);
     }
 
-    function withdraw() public onlyOwner {
-        payable(owner).transfer(address(this).balance);
+    function withdraw() public onlyOwner nonReentrant {
+        (bool success, ) = owner().call{value: address(this).balance}("");
+        require(success, "Transfer failed");
     }
 } 
\ No newline at end of file
diff --git a/backend/hardhat.config.cjs b/backend/hardhat.config.cjs
deleted file mode 100644
index cd28b26..0000000
--- a/backend/hardhat.config.cjs
+++ /dev/null
@@ -1,12 +0,0 @@
-require("@nomiclabs/hardhat-waffle");
-require("dotenv").config();
-
-module.exports = {
-  solidity: "0.8.0",
-  networks: {
-    sepolia: {
-      url: process.env.ETHEREUM_NETWORK_URL,
-      accounts: [process.env.PRIVATE_KEY]
-    }
-  }
-}; 
\ No newline at end of file
diff --git a/backend/hardhat.config.js b/backend/hardhat.config.js
index a875842..79ee7b3 100644
--- a/backend/hardhat.config.js
+++ b/backend/hardhat.config.js
@@ -1,12 +1,12 @@
-require('dotenv').config()
-require('@nomicfoundation/hardhat-ethers')
-require('@nomicfoundation/hardhat-chai-matchers')
+require("dotenv").config();
+require("@nomicfoundation/hardhat-ethers");
+require("@nomicfoundation/hardhat-chai-matchers");
 
 module.exports = {
-  solidity: "0.8.0",
+  solidity: "0.8.19",
   networks: {
     sepolia: {
-      url: process.env.SEPOLIA_URL,
+      url: process.env.ETHEREUM_NETWORK_URL,
       accounts: [process.env.PRIVATE_KEY]
     }
   }
diff --git a/backend/package.json b/backend/package.json
index 1a66517..fdf0365 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -2,7 +2,6 @@
   "name": "backend",
   "version": "1.0.0",
   "license": "MIT",
-  "type": "module",
   "scripts": {
     "compile": "hardhat compile",
     "deploy": "hardhat run scripts/deploy.js --network sepolia",
@@ -14,16 +13,16 @@
     "cors": "^2.8.5",
     "express": "^4.18.3",
     "express-session": "^1.18.0",
-    "hardhat": "^2.20.1",
-    "siwe": "^3.0.0",
-    "nodemon": "^3.1.0"
+    "nodemon": "^3.1.0",
+    "siwe": "^3.0.0"
   },
   "devDependencies": {
+    "hardhat": "^2.21.0",
     "@nomicfoundation/hardhat-ethers": "^3.0.5",
     "@nomicfoundation/hardhat-chai-matchers": "^2.0.0",
-    "@types/sinon-chai": "^3.2.3",
+    "@openzeppelin/contracts": "4.9.3",
     "chai": "4.3.7",
     "dotenv": "^16.4.7",
     "ethers": "^6.11.1"
   }
-}
\ No newline at end of file
+}
diff --git a/backend/scripts/deploy.js b/backend/scripts/deploy.js
index 559bc6b..7224e86 100644
--- a/backend/scripts/deploy.js
+++ b/backend/scripts/deploy.js
@@ -1,12 +1,17 @@
+const hre = require("hardhat");
+
 async function main() {
-  const [deployer] = await ethers.getSigners();
+  console.log("Начинаем деплой контракта...");
 
-  console.log('Deploying contracts with the account:', deployer.address);
+  // Получаем контракт
+  const MyContract = await hre.ethers.getContractFactory("MyContract");
+  
+  // Деплоим контракт
+  const myContract = await MyContract.deploy();
+  await myContract.waitForDeployment();
 
-  const MyContract = await ethers.getContractFactory('MyContract');
-  const contract = await MyContract.deploy();
-
-  console.log('Contract deployed to:', contract.address);
+  const address = await myContract.getAddress();
+  console.log("Контракт развернут по адресу:", address);
 }
 
 main()
diff --git a/backend/server.js b/backend/server.js
index b2c74ab..c0a9c82 100644
--- a/backend/server.js
+++ b/backend/server.js
@@ -1,12 +1,8 @@
-import express from 'express';
-import cors from 'cors';
-import session from 'express-session';
-import { SiweMessage, generateNonce } from 'siwe';
-import { fileURLToPath } from 'url';
-import { dirname } from 'path';
-
-const __filename = fileURLToPath(import.meta.url);
-const __dirname = dirname(__filename);
+const express = require('express');
+const cors = require('cors');
+const session = require('express-session');
+const { SiweMessage, generateNonce } = require('siwe');
+const path = require('path');
 
 const app = express();
 
@@ -69,57 +65,37 @@ app.post('/verify', async (req, res) => {
       throw new Error('Invalid session');
     }
     
-    if (!signature || !message) {
-      console.error('Отсутствует подпись или сообщение');
-      throw new Error('Invalid signature or message');
-    }
-
-    // Создаем и верифицируем SIWE сообщение
-    console.log('Начинаем парсинг SIWE сообщения...');
-    const siweMessage = new SiweMessage(message);
-    
-    console.log('Парсинг успешен:', {
-      domain: siweMessage.domain,
-      address: siweMessage.address,
-      nonce: siweMessage.nonce
-    });
-    
-    const { success, data: fields } = await siweMessage.verify({ 
-      signature,
-      domain: siweMessage.domain,
-      nonce: req.session.nonce
-    });
-    
-    console.log('Результат верификации:', { success, fields });
-    
-    if (!success) {
-      throw new Error('Signature verification failed');
-    }
-    
-    // Сохраняем сессию
-    req.session.authenticated = true;
-    req.session.siwe = fields;
-    
-    console.log('Сессия сохранена:', {
-      authenticated: true,
-      address: fields.address
-    });
-    
-    req.session.save(() => {
-      console.log('Session saved successfully');
-      res.status(200).json({ 
+    let siweMessage;
+    try {
+      siweMessage = new SiweMessage(message);
+      const fields = await siweMessage.validate(signature);
+      
+      if (fields.nonce !== req.session.nonce) {
+        console.error('Nonce не совпадает');
+        throw new Error('Invalid nonce');
+      }
+      
+      console.log('Сообщение успешно верифицировано');
+      req.session.siwe = fields;
+      req.session.authenticated = true;
+      req.session.nonce = null;
+      
+      res.json({ 
         success: true,
-        address: fields.address
+        address: fields.address 
       });
-    });
+    } catch (error) {
+      console.error('Ошибка валидации сообщения:', error);
+      req.session.authenticated = false;
+      req.session.siwe = null;
+      req.session.nonce = null;
+      throw error;
+    }
   } catch (error) {
     console.error('Ошибка верификации:', error);
-    req.session.authenticated = false;
-    req.session.nonce = null;
-    req.session.siwe = null;
     res.status(400).json({ 
-      error: 'Verification failed',
-      message: error.message 
+      success: false,
+      error: error.message 
     });
   }
 });
@@ -184,7 +160,7 @@ app.use((err, req, res, next) => {
   });
 });
 
-const PORT = 3000;
+const PORT = process.env.PORT || 3000;
 app.listen(PORT, () => {
   console.log(`SIWE сервер запущен на порту ${PORT}`);
   console.log('Доступные эндпоинты:');
diff --git a/backend/yarn.lock b/backend/yarn.lock
index 598dd47..e59c129 100644
--- a/backend/yarn.lock
+++ b/backend/yarn.lock
@@ -371,6 +371,11 @@
     "@nomicfoundation/solidity-analyzer-linux-x64-musl" "0.1.2"
     "@nomicfoundation/solidity-analyzer-win32-x64-msvc" "0.1.2"
 
+"@openzeppelin/contracts@4.9.3":
+  version "4.9.3"
+  resolved "https://registry.yarnpkg.com/@openzeppelin/contracts/-/contracts-4.9.3.tgz#00d7a8cf35a475b160b3f0293a6403c511099364"
+  integrity sha512-He3LieZ1pP2TNt5JbkPA4PNT9WC3gOTOlDcFGJW4Le4QKqwmiNJCRt44APfxMxvq7OugU/cqYuPcSBzOw38DAg==
+
 "@scure/base@~1.1.0":
   version "1.1.9"
   resolved "https://registry.yarnpkg.com/@scure/base/-/base-1.1.9.tgz#e5e142fbbfe251091f9c5f1dd4c834ac04c3dbd1"
@@ -560,26 +565,6 @@
   dependencies:
     "@types/node" "*"
 
-"@types/sinon-chai@^3.2.3":
-  version "3.2.12"
-  resolved "https://registry.yarnpkg.com/@types/sinon-chai/-/sinon-chai-3.2.12.tgz#c7cb06bee44a534ec84f3a5534c3a3a46fd779b6"
-  integrity sha512-9y0Gflk3b0+NhQZ/oxGtaAJDvRywCa5sIyaVnounqLvmf93yBF4EgIRspePtkMs3Tr844nCclYMlcCNmLCvjuQ==
-  dependencies:
-    "@types/chai" "*"
-    "@types/sinon" "*"
-
-"@types/sinon@*":
-  version "17.0.3"
-  resolved "https://registry.yarnpkg.com/@types/sinon/-/sinon-17.0.3.tgz#9aa7e62f0a323b9ead177ed23a36ea757141a5fa"
-  integrity sha512-j3uovdn8ewky9kRBG19bOwaZbexJu/XjtkHyjvUgt4xfPFz18dcORIMqnYh66Fx3Powhcr85NT5+er3+oViapw==
-  dependencies:
-    "@types/sinonjs__fake-timers" "*"
-
-"@types/sinonjs__fake-timers@*":
-  version "8.1.5"
-  resolved "https://registry.yarnpkg.com/@types/sinonjs__fake-timers/-/sinonjs__fake-timers-8.1.5.tgz#5fd3592ff10c1e9695d377020c033116cc2889f2"
-  integrity sha512-mQkU2jY8jJEF7YHjHvsQO8+3ughTL1mcnn96igfhONmR+fUPSKIkefQYpSe8bsly2Ep7oQbn/6VG5/9/0qcArQ==
-
 accepts@~1.3.8:
   version "1.3.8"
   resolved "https://registry.yarnpkg.com/accepts/-/accepts-1.3.8.tgz#0bf0be125b67014adcb0b0921e62db7bffe16b2e"
@@ -1448,7 +1433,7 @@ graceful-fs@^4.1.2, graceful-fs@^4.1.6:
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.2.11.tgz#4183e4e8bf08bb6e05bbb2f7d2e0c8f712ca40e3"
   integrity sha512-RbJ5/jmFcNNCcDV5o9eTnBLJ/HszWV0P73bc+Ff4nS/rJj+YaS6IGyiOL0VoBYX+l1Wrl3k63h/KrH+nhJ0XvQ==
 
-hardhat@^2.20.1:
+hardhat@^2.21.0:
   version "2.22.18"
   resolved "https://registry.yarnpkg.com/hardhat/-/hardhat-2.22.18.tgz#e299a26a67b521bbb225370eb47a032d4e097e3a"
   integrity sha512-2+kUz39gvMo56s75cfLBhiFedkQf+gXdrwCcz4R/5wW0oBdwiyfj2q9BIkMoaA0WIGYYMU2I1Cc4ucTunhfjzw==
diff --git a/frontend/src/components/ContractInteraction.vue b/frontend/src/components/ContractInteraction.vue
index 8d6b703..00206bf 100644
--- a/frontend/src/components/ContractInteraction.vue
+++ b/frontend/src/components/ContractInteraction.vue
@@ -105,7 +105,7 @@ const isAuthenticated = ref(false)
 // Константы
 const SEPOLIA_CHAIN_ID = 11155111
 const provider = new JsonRpcProvider(import.meta.env.VITE_APP_ETHEREUM_NETWORK_URL)
-const contractAddress = '0xD1789d2E00e4af3157330ADFbb813427696c8A01'
+const contractAddress = '0xFF7602583E82C097Ae548Fc8B894F0a73089985E'
 const contractABI = [
   'function purchase(uint256 amount) payable',
   'function price() view returns (uint256)',