Flutter - Generate Strong Random Password

Last Updated : 21 Apr, 2025

In this article, we are going to make an application in Flutter that generates random passwords that cannot be easily cracked by hackers or attackers. Here we define a method named _generatePassword that is responsible for generating random passwords. It uses a mix of lowercase letters, uppercase letters, numbers, and special characters.

Step-by-Step Implementation

Step 1: Create a New Flutter Application

Create a new Flutter application using the command Prompt. To create a new app, write the following command and run it.

flutter create app_name

To know more about it refer this article: Creating a Simple Application in Flutter

Step 2: Import the Package

First of all, import material.dart file.

import 'package:flutter/material.dart';
import 'dart:math';

Step 3: Execute the main Method

Here, the execution of our app starts.

Dart

void main() {
  runApp(MyApp());
}

Step 4: Create MyApp Class

In this class we are going to implement the MaterialApp , here we are also set the Theme of our App.

Dart

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        debugShowCheckedModeBanner: false,
        home: PasswordGenerator());
  }
}

Step 5: Create PasswordGenerator Class

In this class we are going to define a method that is responsible for generating random passsword with a mixture of Uppercase,Lowercase,numbers and Special Characters.

Dart

// Method for Generating Random Passwords
void _generatePassword() {
    
    final random = Random();
    final characters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#\$%^&*()_+';
    String password = '';
    
    for (int i = 0; i < 12; i++) {
        
        // Generate a random password
        password += characters[random.nextInt(characters.length)]; 
    }
    setState(() {
        
        // Update the displayed password
        _password = password; 
    });
}

When we click a Button, the above method is called an generate a Strong password with a combination of Uppercase, LowerCase, numbers, and Special Characters. Then the password is displayed using a TextView.

Dart

class PasswordGenerator extends StatefulWidget {
  @override
  _PasswordGeneratorState createState() => _PasswordGeneratorState();
}

class _PasswordGeneratorState extends State<PasswordGenerator> {
  
  String _password = '';
  
  // Method for Generating Random Passwords
  void _generatePassword() {
      
    final random = Random();
    final characters ='abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#\$%^&*()_+';
    String password = '';
    
    for (int i = 0; i < 12; i++) {
        
        // Generate a random password
        password += characters[random.nextInt(characters.length)]; 
    }
    
    setState(() {
      
        // Update the displayed password
        _password = password; 
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Password Generator'), 
        backgroundColor: Colors.green,
        foregroundColor: Colors.white,
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              'Your Password:', 
              style: TextStyle(fontSize: 18),
            ),
            Text(
                
              // Displayed password
              _password, 
              style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold),
            ),
            SizedBox(height: 20), 
            ElevatedButton(
              style: ElevatedButton.styleFrom(
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(5), 
                ),
                backgroundColor: Colors.green, 
                foregroundColor: Colors.white,
              ),
              
              // Call _generatePassword when button is pressed
              onPressed:_generatePassword, 
              child: Text('Generate Password'), 
            ),
          ],
        ),
      ),
    );
  }
}

Complete Source Code

main.dart:

Dart

import 'package:flutter/material.dart';
import 'dart:math';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        theme: ThemeData(
          
          // Set the app's primary theme color
          primarySwatch: Colors.green, 
        ),
        debugShowCheckedModeBanner: false,
        home: PasswordGenerator());
  }
}

class PasswordGenerator extends StatefulWidget {
  @override
  _PasswordGeneratorState createState() => _PasswordGeneratorState();
}

class _PasswordGeneratorState extends State<PasswordGenerator> {
  String _password = '';
  
  // Method for Generating Random Passwords
  void _generatePassword() {
    final random = Random();
    final characters ='abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#\$%^&*()_+';
    String password = '';
    for (int i = 0; i < 12; i++) {
          
          // Generate a random password
          password += characters[random.nextInt(characters.length)]; 
    }
    setState(() {
      
      // Update the displayed password
      _password = password; 
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Password Generator'), 
        backgroundColor: Colors.green,
        foregroundColor: Colors.white,
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              'Your Password:', 
              style: TextStyle(fontSize: 18),
            ),
            Text(
                
              // Displayed password
              _password, 
              style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold),
            ),
            SizedBox(height: 20), 
            ElevatedButton(
              style: ElevatedButton.styleFrom(
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(5), 
                ),
                backgroundColor: Colors.green, 
                foregroundColor: Colors.white,
              ),
              
              // Call _generatePassword when button is pressed
              onPressed:_generatePassword, 
              child: Text('Generate Password'), 
            ),
          ],
        ),
      ),
    );
  }
}