String Masker

A Flutter package for masking and validating sensitive data like emails, phone numbers, and credit cards.

Features

  • 🔒 Mask sensitive data (emails, phone numbers, credit cards)
  • ✅ Built-in validation for common formats
  • 🎯 Custom masking patterns
  • 🛡️ Input validation before masking
  • 🎨 Customizable mask characters

Installation

Add this to your package's pubspec.yaml file:

dependencies:
  string_masker: ^1.0.0

Usage

Basic Usage

import 'package:string_masker/string_masker.dart';

// Mask an email
String? maskedEmail = StringMasker.mask(
  '[email protected]',
  type: MaskType.email,
); // Returns: "j******@e******.com"

// Mask a phone number
String? maskedPhone = StringMasker.mask(
  '+1 (555) 123-4567',
  type: MaskType.phone,
); // Returns: "+1 (5*****3-67"

// Mask a credit card
String? maskedCard = StringMasker.mask(
  '4532715337901241',
  type: MaskType.card,
); // Returns: "**** **** **** 1241"

// Custom masking
String? maskedCustom = StringMasker.mask(
  'Hello World',
  type: MaskType.custom,
  start: 2,
  end: 3,
  maskChar: '#',
); // Returns: "He###World"

Validation

The package includes built-in validators for common data types:

// Email validation
bool isValidEmail = StringValidator.isValidEmail('[email protected]');

// Phone validation
bool isValidPhone = StringValidator.isValidPhone('+1 (555) 123-4567');

// Credit card validation (uses Luhn algorithm)
bool isValidCard = StringValidator.isValidCard('4532715337901241');

// Password validation
bool isValidPassword = StringValidator.isValidPassword(
  'MyPass123!',
  minLength: 8,
  requireUppercase: true,
  requireLowercase: true,
  requireNumbers: true,
  requireSpecialChars: true,
);

Masking with Validation

The mask method automatically validates input before masking:

String? result = StringMasker.mask(
  'invalid.email',
  type: MaskType.email,
); // Returns: null (invalid email)

if (result == null) {
  print('Invalid input - masking failed');
} else {
  print('Masked result: $result');
}

Available Mask Types

  • MaskType.email - Masks email addresses while preserving format
  • MaskType.phone - Masks phone numbers while keeping prefix/suffix
  • MaskType.card - Masks credit card numbers (shows last 4 digits)
  • MaskType.custom - Custom masking with configurable start/end positions

Validation Features

Email Validation

Phone Validation

  • International format support
  • Optional '+' prefix
  • 8-15 digits length
  • Flexible formatting

Credit Card Validation

  • Luhn algorithm implementation
  • 13-19 digits length
  • Removes non-digit characters
  • Major card types support

Password Validation

  • Minimum length check
  • Uppercase letters requirement
  • Lowercase letters requirement
  • Numbers requirement
  • Special characters requirement
  • Customizable requirements

Example

Check out the example directory for a complete sample application demonstrating all features.

Additional Information

License

MIT License

Copyright (c) 2025

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Libraries

string_masker