Walter.Web.Cypher.EF 2025.2.26.1615

WALTER

Introducing the WALTER Framework: Workable Algorithms for Location-aware Transmission, Encryption Response. Designed for modern developers, WALTER is a groundbreaking suite of NuGet packages crafted for excellence in .NET Standard 2.0, 2.1, Core 3.1, and .NET 6, 7, 8, as well as C++ environments. Emphasizing 100% AoT support and reflection-free operations, this framework is the epitome of performance and stability.

Whether you're tackling networking, encryption, or secure communication, WALTER offers unparalleled efficiency and precision in processing, making it an essential tool for developers who prioritize speed and memory management in their applications.

Walter.Cypher.Secure - Encrypted Data Storage

Overview

The Walter.Cypher.Secure class, part of the Walter.Web.Cypher.EF NuGet package, provides a secure way to store and manage encrypted data within an application. This is particularly useful when dealing with sensitive data, such as personally identifiable information (PII) under GDPR regulations or proprietary business data, especially when the database is hosted on a server you do not fully control (e.g., a cloud-managed database).

Key Features

• Transparent Encryption & Decryption: Data is automatically encrypted before storage and decrypted when retrieved.
• Data Protection Against DBAs: Even database administrators cannot access the plaintext values.
• Searchability via Hashing: Allows for searching encrypted data using one-way deterministic hashes.
• Entity Framework Integration: Seamlessly integrates with EF Core.
• Optional SecureDbContext: A specialized DbContext that automatically encrypts and decrypts properties marked with the [Encrypted] attribute.

Usage Example: Invoce Class

The Invoce class extends Walter.Cypher.Secure to securely store sensitive invoice details, such as order references.

Implementation

public class Invoce : Walter.Cypher.Secure
{
    private string _orderRef;

    [Encrypted(nameof(_orderRef))]
    public string OrderRef
    {
        get => Decrypt(_orderRef);
        set
        {
            _orderRef = Encrypt(value);
            OrderRefCs = value?.GetDeterministicHashCode();
        }
    }

    public int? OrderRefCs { get; set; }
    public decimal InvoiceAmmount { get; set; }
    public decimal Discount { get; set; }
    public decimal VAT { get; set; }
    public DateTime InvouceDate { get; set; } = DateTime.Now;
    public DateTime DueData { get; set; } = DateTime.Now.AddDays(60);
    public PaymentStatus Status { get; set; }
}

Explanation

• Field Encryption: The OrderRef property is stored encrypted in _orderRef, using the Encrypt and Decrypt methods.
• Searchable Hashing: A deterministic hash (OrderRefCs) is stored alongside the encrypted data for search purposes.
• Data Protection: The encryption ensures that even if the database is compromised, sensitive information remains protected.

SecureDbContext for Automatic Encryption

To simplify encryption management across multiple entity models, the SecureDbContext can be used. It automatically applies encryption and decryption for all properties marked with [Encrypted].

Implementation

public class SecureDbContext : DbContext
{
    protected void BindEncryption(ModelBuilder modelBuilder)
    {
        if (modelBuilder is null)
        {
            throw new ArgumentNullException(nameof(modelBuilder));
        }

        Hookup(modelBuilder);
    }

    private void Hookup(ModelBuilder modelBuilder)
    {
        foreach (var entityType in modelBuilder.Model.GetEntityTypes())
        {
            foreach (var property in entityType.GetProperties())
            {
                var attributes = property.PropertyInfo?.GetCustomAttributes(typeof(EncryptedAttribute), false);
                if (attributes?.Length > 0 && attributes[0] is EncryptedAttribute e)
                {
                    property.SetField(e.FieldName);
                    property.SetPropertyAccessMode(PropertyAccessMode.Field);
                }
            }
        }
    }
}

Benefits of SecureDbContext

• Automatic Encryption Handling: Reduces manual encryption calls in entity classes.
• Consistency: Ensures all encrypted properties follow the same rules.
• Ease of Use: Developers only need to mark properties with [Encrypted].

How It Works

1. Encrypting Data
   • Before storing a value in the database, it is encrypted using the Encrypt() method.
2. Decrypting Data
   • When retrieving the value, it is decrypted using Decrypt().
3. Searching Encrypted Data
   • Since encrypted data is not directly searchable, a deterministic hash of the original value can be stored to facilitate lookups.

Why Use Walter.Cypher.Secure?

• Security: Ensures sensitive data is never stored in plaintext.
• Compliance: Helps meet data protection regulations (e.g., GDPR, HIPAA).
• Seamless Integration: Works naturally with EF Core and existing entity models.
• Optional SecureDbContext: Provides automatic encryption handling for EF Core entities.

Installation

To use Walter.Cypher.Secure, install the Walter.Web.Cypher.EF NuGet package:

Install-Package Walter.Web.Cypher.EF

Conclusion

The Walter.Cypher.Secure class is an essential tool for securely handling sensitive data in applications where data privacy and compliance are critical. By integrating encrypted storage seamlessly into EF Core entities, it ensures that no unauthorized party—including database administrators—can access protected information. Additionally, using SecureDbContext simplifies the management of encrypted data across multiple entities, making it a powerful option for enterprise applications.