Client side field encryption on array of object

[Prashanth Viswanathan]

Hi All,
    My application runs on Java 11 and connects to MOngo entrprise DB 4.2.X and I am trying to encrypt an array that is part of my java DTO object that is persisted into a collection on the DB. The objects stored in the array are of a custom class that is part of my application and the structire of these is as follows:-

public class MyPersistedDTO{
private List<AttributeDto> attributes
}

public class AttributeDto {
 private String name;
 private int type;
 private String value;
}

I need to create the encryption schema map such that when the MyPersistedDTO.attributes is persisted, only the AttributeDto.value field is encrypted for each of the elements in the array as AEAD_AES_256_CBC_HMAC_SHA_512-Deterministic so that it can be queried on from the application. Is there a way to do this. If so please share the schema map with me as I need it urgently. Thanks.

[Tim Holloway]

Welcome to the Ranch, Prashanth!

I'm not sure I'd call that a "DTO". A Data Transfer Object was originally part of the design pattern architecture for JEE EJBs. Since EJBs weren't POJOs and you couldn't use them in generic logic, you'd use a (POJO) DTO to transfer data to/from your non-EJB logic to your EJBs. So I think what you actually have here is an Entity object. It's quite possible that if you were using the Spring Data framework that you would even annotate them as @Entity, even though MongoDB is a noSQL DBMS. Spring Data likes to make similar things similar.

As for defining per-field encryption within a MongoDB entity, I'm not optimistic. Originally, MongoDB was designed as a dictionary system, so the concept of fixed schemas of any type was quite foreign to it. Someone who is more up to date might be able to help here.