问使用EF6和身份提供程序安全地存储列数据

EN

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field)]
public class StoreSecurelyAttribute : Attribute { }

public class UserProfileInfo
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid Id { get; set; }

    [Required, StoreSecurely]
    public string SomePersonalInformation { get; set; }
}

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    public ApplicationDbContext() : base("DefaultConnection", false)
    {
        var ctx = ((IObjectContextAdapter) this).ObjectContext;
        ctx.ObjectMaterialized += OnObjectMaterialized;
        ctx.SavingChanges += OnSavingChanges;
    }

    void OnSavingChanges(object sender, EventArgs e)
    {
        foreach (var entry in ((ObjectContext) sender).ObjectStateManager.GetObjectStateEntries(EntityState.Added |
                                                                                  EntityState.Modified))
        {
            foreach (var propInfo in entry.Entity.GetType().GetProperties()
                .Where(prop => prop.PropertyType == typeof(string) && Attribute.IsDefined(prop, typeof(StoreSecurelyAttribute))))
            {
                var plainTextValue = propInfo.GetValue(entry.Entity) as string;
                // TODO: encrypt using injected encryption provider
                var encryptedValue = Encrypt(plainTextValue); 
                propInfo.SetValue(entry.Entity, encryptedValue);
            }
        }
    }

    void OnObjectMaterialized(object sender, ObjectMaterializedEventArgs e)
    {
        foreach (var propInfo in e.Entity.GetType().GetProperties()
                .Where(prop => prop.PropertyType == typeof(string) && Attribute.IsDefined(prop, typeof(StoreSecurelyAttribute))))
            {
                var encryptedValue = propInfo.GetValue(e.Entity) as string;
                // TODO: decrypt using injected encryption provider
                var plainTextValue = Decrypt(encryptedValue);
                propInfo.SetValue(e.Entity, plainTextValue);
            }
    }
    public override int SaveChanges()
    {
        // Hold onto them before their state changes and they're no longer "added" or "modified"
        var entries = ChangeTracker.Entries().Where(x => x.State == EntityState.Added || x.State == EntityState.Modified).ToList();

        // Go Ahead and save...
        var result = base.SaveChanges();

        // After saving to db, we want our local hydrated object to be "correct" so... decrypt...
        foreach (var entry in entries)
        {
            foreach (var propInfo in entry.Entity.GetType().GetProperties()
                .Where(prop => prop.PropertyType == typeof(string) && Attribute.IsDefined(prop, typeof(StoreSecurelyAttribute))))
            {
                var encryptedValue = propInfo.GetValue(entry.Entity) as string;
                var plainTextValue = Decrypt(encryptedValue);
                propInfo.SetValue(entry.Entity, plainTextValue);
            }
        }

        return result;
    }
// ... snip ...
}