How to restrict updates on table by column value?

I have a table that stores data about NFT collections. This gets populated by a smart contract event that I’m watching. However, I want to be able to link a “collection thumbnail” to each collection, and I suppose the best way to store each one is inside that same table. How can I restrict this operation so that only the user whose address is the same as “author” (name of the column in that table) can do it?

You can use beforeSave and set the thumbnail and also ACL on the object before it’s saved