Difference between JPA's AttributeConverter and Hibernate's ColumnTransformer in terms of Encryption and Decryption of attributes

Question

I have a database which has some tables with encrypted columns. As of now, all these columns are of String type. I am using JPA's @Converter to encrypt and decrypt a column in a table. However, I also know, that I can use Hibernate's @ColumnTransformer to achieve the same objective of encryption and decryption while read and write operations. My question is how are they different and which is a better approach to use in terms of speed, maintainability, future enhancement, etc? Right now, @Converter is working fine with String type of data. I am not sure it will work with Integer type or I will have to create a new Converter class.

Answer 1

They're very similar and in many cases can be used for exactly the same thing, but the implementations of the solutions varies a bit.

One primary difference is that one is Hibernate specific and the other is part of the JPA specification. If you want to write code matching the specification, use @Converter and you'll be able to use other implementations besides Hibernate with your code.

Another major difference is that @ColumnTransformer operates on the database level whereas @Converter reads the value from the database as is, then converts it to something else on the application side. This may provide performance advantages for @ColumnTransformer as the database performs some operations.

Additionally you can actually create an AttributeConverter that applies automatically to all values of a given type. This can be advantageous for example in refactoring situations where you don't want to manually add a @Converter annotation to many places.

So they can both be used to perform similar things and neither is implicitly better than the other.