I want to know whether my deed is illegal or not?

The only way to answer that is to examine the specific terms of your licence agreement.
Speak to the Library supplier.
Remember, this is a legal question, so you need to seek legal advice. I dunno if we have any lawyers on the forum...?

Many software licences have a clause prohibiting reverse-engineering, which is effectively what you've done. Therefore my guess would be that, technically, it's not legal.
But remember, I am not a lawyer.