Password Validator API

A .NET 9 Web API for validating passwords and storing validation attempts in SQL Server.

Features

• Password validation with multiple rules
• Secure password hashing (SHA256)
• SQL Server database storage
• RESTful API endpoints
• CORS enabled for frontend integration

Prerequisites

• .NET 9 SDK
• Docker (for SQL Server)
• VS Code with C# extension (recommended)

Getting Started

1. Start SQL Server (Docker)

docker run -e "ACCEPT_EULA=1" -e "MSSQL_SA_PASSWORD=YourPassword123!" \
   -p 1434:1433 --name sqlserver-password-validator \
   -d mcr.microsoft.com/azure-sql-edge

2. Configure User Secrets

cd PasswordValidatorAPI
dotnet user-secrets init
dotnet user-secrets set "ConnectionStrings:DefaultConnection" "Server=localhost,1434;Database=PasswordValidatorDB;User Id=sa;Password=YourPassword123!;TrustServerCertificate=True;"

3. Install Dependencies

dotnet restore

4. Run Migrations

dotnet ef migrations add InitialCreate
dotnet ef database update

5. Run the API

dotnet run

The API will start on https://localhost:5001 or http://localhost:5000.

Project Structure

PasswordValidatorAPI/
├── Controllers/
│   └── PasswordController.cs    # API endpoints
├── Data/
│   └── AppDbContext.cs          # Entity Framework DbContext
├── Models/
│   └── ValidationAttempt.cs     # Database model
├── Dtos/
│   └── PasswordRequestDto.cs    # Data transfer objects
├── Services/
│   └── PasswordService.cs       # Password validation logic
├── Migrations/                  # EF Core migrations
└── Program.cs                   # Application entry point

API Endpoints

POST /api/password/validate

Validates a password and stores the attempt in the database.

Request Body:

{
    "password": "MyPassword123!"
}

Response:

{
    "isValid": true,
    "errors": []
}

Or if invalid:

{
    "isValid": false,
    "errors": ["Password must be at least 8 characters long", "Password must contain at least one special character"]
}

Password Validation Rules

• Minimum 8 characters
• At least one uppercase letter
• At least one lowercase letter
• At least one number
• At least one special character

Database Schema

ValidationAttempts Table

Column	Type	Description
Id	int	Primary key (auto-increment)
PasswordHash	nvarchar(max)	SHA256 hash of password
IsValid	bit	Whether password passed validation
ValidationErrors	nvarchar(max)	Comma-separated error messages
Timestamp	datetime2	When validation occurred (UTC)

Technologies Used

• ASP.NET Core 9.0 - Web API framework
• Entity Framework Core 9.0 - ORM
• SQL Server (Azure SQL Edge) - Database
• Docker - Container platform
• SHA256 - Password hashing

Security Notes

• Passwords are hashed using SHA256 before storage
• User secrets are used for local development (connection strings)
• CORS is configured to allow requests from http://localhost:3000 (React app)

Common Commands

# Run the API
dotnet run

# Build the project
dotnet build

# Create a new migration
dotnet ef migrations add MigrationName

# Apply migrations
dotnet ef database update

# List user secrets
dotnet user-secrets list

# Stop SQL Server container
docker stop sqlserver-password-validator

# Start SQL Server container
docker start sqlserver-password-validator

Troubleshooting

Cannot connect to database

• Ensure Docker container is running: docker ps
• Verify connection string in user secrets: dotnet user-secrets list
• Check SQL Server password matches between Docker and user secrets

Migration errors

• Delete the Migrations folder and obj folder
• Run dotnet ef migrations add InitialCreate again
• Run dotnet ef database update

CORS errors from frontend

• Ensure app.UseCors("AllowReactApp") is in Program.cs
• Verify React app is running on http://localhost:3000

License

This project is for educational purposes.