csharp .NET EntityFramework加密示例（C＃）

Posted 2021-05-12

public class MyDB : IdentityDbContext<User>
{  
    //DBSet properties go here

	public MyDB()
	{
		((IObjectContextAdapter)this).ObjectContext.ObjectMaterialized += new ObjectMaterializedEventHandler(ObjectMaterialized);
	}

	#region Encryption

	public override int SaveChanges()
	{
		var contextAdapter = ((IObjectContextAdapter)this);

		contextAdapter.ObjectContext.DetectChanges(); //force this. Sometimes entity state needs a handle jiggle

		var pendingEntities = contextAdapter.ObjectContext.ObjectStateManager
			.GetObjectStateEntries(EntityState.Added | EntityState.Modified)
			.Where(en => !en.IsRelationship).ToList();

		foreach (var entry in pendingEntities) //Encrypt all pending changes
			EncryptEntity(entry.Entity);

		int result = base.SaveChanges();

		foreach (var entry in pendingEntities) //Decrypt updated entities for continued use
			DecryptEntity(entry.Entity);

		return result;
	}

	public override async Task<int> SaveChangesAsync(System.Threading.CancellationToken cancellationToken)
	{
		var contextAdapter = ((IObjectContextAdapter)this);

		contextAdapter.ObjectContext.DetectChanges(); //force this. Sometimes entity state needs a handle jiggle

		var pendingEntities = contextAdapter.ObjectContext.ObjectStateManager
			.GetObjectStateEntries(EntityState.Added | EntityState.Modified)
			.Where(en => !en.IsRelationship).ToList();

		foreach (var entry in pendingEntities) //Encrypt all pending changes
			EncryptEntity(entry.Entity);

		var result = await base.SaveChangesAsync(cancellationToken);

		foreach (var entry in pendingEntities) //Decrypt updated entities for continued use
			DecryptEntity(entry.Entity);

		return result;
	}

	void ObjectMaterialized(object sender, ObjectMaterializedEventArgs e)
	{
		DecryptEntity(e.Entity);
	}

	private void EncryptEntity(object entity)
	{
		//Get all the properties that are encryptable and encrypt them
		var encryptedProperties = entity.GetType().GetProperties()
			.Where(p => p.GetCustomAttributes(typeof(Encrypted), true).Any(a => p.PropertyType == typeof(String)));
		foreach (var property in encryptedProperties)
		{
			string value = property.GetValue(entity) as string;
			if (!String.IsNullOrEmpty(value))
			{
				string encryptedValue = EncryptionService.Encrypt(value);
				property.SetValue(entity, encryptedValue);
			}
		}
	}

	private void DecryptEntity(object entity)
	{
		//Get all the properties that are encryptable and decyrpt them
		var encryptedProperties = entity.GetType().GetProperties()
			.Where(p => p.GetCustomAttributes(typeof(Encrypted), true).Any(a => p.PropertyType == typeof(String)));

		foreach (var property in encryptedProperties)
		{
			string encryptedValue = property.GetValue(entity) as string;
			if (!String.IsNullOrEmpty(encryptedValue))
			{
				string value = EncryptionService.Decrypt(encryptedValue);
				this.Entry(entity).Property(property.Name).OriginalValue = value;
				this.Entry(entity).Property(property.Name).IsModified = false;
			}
		}
	}
	
	#endregion Encryption
}