EntityFrameworkCore.DataEncryption

EntityFrameworkCore.DataEncryption is a Microsoft Entity Framework Core extension to add support of encrypted fields using built-in or custom encryption providers.

Disclaimer

:warning: This project is **not** affiliated with Microsoft. :warning:

This library has been developed initialy for a personal project of mine which suits my use case. It provides a simple way to encrypt column data.

I do not take responsability if you use/deploy this in a production environment and loose your encryption key or corrupt your data.

How to install

Install the package from NuGet or from the Package Manager Console :

PM> Install-Package EntityFrameworkCore.DataEncryption

Supported types

Built-in providers

How to use

EntityFrameworkCore.DataEncryption supports 2 differents initialization methods:

• Attribute
• Fluent configuration

Depending on the initialization method you will use, you will need to decorate your string or byte[] properties of your entities with the [Encrypted] attribute or use the fluent IsEncrypted() method in your model configuration process. To use an encryption provider on your EF Core model, and enable the encryption on the ModelBuilder.

Example with AesProvider and attribute

public class UserEntity
{
	public int Id { get; set; }
	
	[Encrypted]
	public string Username { get; set; }
	
	[Encrypted]
	public string Password { get; set; }
	
	public int Age { get; set; }
}

public class DatabaseContext : DbContext
{
	// Get key and IV from a Base64String or any other ways.
	// You can generate a key and IV using "AesProvider.GenerateKey()"
	private readonly byte[] _encryptionKey = ...; 
	private readonly byte[] _encryptionIV = ...;
	private readonly IEncryptionProvider _provider;

	public DbSet<UserEntity> Users { get; set; }
	
	public DatabaseContext(DbContextOptions options)
		: base(options)
	{
		_provider = new AesProvider(this._encryptionKey, this._encryptionIV);
	}
	
	protected override void OnModelCreating(ModelBuilder modelBuilder)
	{
		modelBuilder.UseEncryption(_provider);
	}
}

The code bellow creates a new AesProvider and gives it to the current model. It will encrypt every string fields of your model that has the [Encrypted] attribute when saving changes to database. As for the decrypt process, it will be done when reading the DbSet<T> of your DbContext.

Example with AesProvider and fluent configuration

public class UserEntity
{
	public int Id { get; set; }
	public string Username { get; set; }
	public string Password { get; set; }
	public int Age { get; set; }
}

public class DatabaseContext : DbContext
{
	// Get key and IV from a Base64String or any other ways.
	// You can generate a key and IV using "AesProvider.GenerateKey()"
	private readonly byte[] _encryptionKey = ...; 
	private readonly byte[] _encryptionIV = ...;
	private readonly IEncryptionProvider _provider;

	public DbSet<UserEntity> Users { get; set; }
	
	public DatabaseContext(DbContextOptions options)
		: base(options)
	{
		_provider = new AesProvider(this._encryptionKey, this._encryptionIV);
	}
	
	protected override void OnModelCreating(ModelBuilder modelBuilder)
	{
		// Entities builder *MUST* be called before UseEncryption().
		var userEntityBuilder = modelBuilder.Entity<UserEntity>();
		
		userEntityBuilder.Property(x => x.Username).IsRequired().IsEncrypted();
		userEntityBuilder.Property(x => x.Password).IsRequired().IsEncrypted();

		modelBuilder.UseEncryption(_provider);
	}
}

Create an encryption provider

EntityFrameworkCore.DataEncryption gives the possibility to create your own encryption providers. To do so, create a new class and make it inherit from IEncryptionProvider. You will need to implement the Encrypt(string) and Decrypt(string) methods.

public class MyCustomEncryptionProvider : IEncryptionProvider
{
	public byte[] Encrypt(byte[] input)
	{
		// Encrypt the given input and return the encrypted data as a byte[].
	}
	
	public byte[] Decrypt(byte[] input)
	{
		// Decrypt the given input and return the decrypted data as a byte[].
	}
}

To use it, simply create a new MyCustomEncryptionProvider in your DbContext and pass it to the UseEncryption method:

public class DatabaseContext : DbContext
{
	private readonly IEncryptionProvider _provider;

	public DatabaseContext(DbContextOptions options)
		: base(options)
	{
		_provider = new MyCustomEncryptionProvider();
	}

	protected override void OnModelCreating(ModelBuilder modelBuilder)
	{
		modelBuilder.UseEncryption(_provider);
	}
}

Important notes

AES Provider structure

The following section describes how encrypted fields using the built-in AES provider encrypts data. There is two available modes :

• Fixed IV
• Dynamic IV

Fixed IV

A fixed IV is generated at setup and is used for every encrypted fields on the database. This might be a security issue depending on your context.

Dynamic IV

For each encrypted field, the provider generates a new IV with a length of 16 bytes. These 16 bytes are written at the begining of the CryptoStream followed by the actual input to encrypt.

Similarly, for reading, the provider reads the first 16 bytes from the input data converted as a byte[] to retrieve the initialization vector and then read the encrypted content.

For more information, checkout the AesProvider class.

:warning: When using Dynamic IV, you cannot use the Entity Framework LINQ extensions because the provider will generate a new IV per value, which will create unexpected behaviors.

Thanks

I would like to thank all the people that supports and contributes to the project and helped to improve the library. :smile:

Credits

Package Icon : from Icons8