How to encrypt connection string without using ASP.net

Question

I created a windows library to do data reading from files and some custom filter, append, remove, update data towards my database on SQL Server. And my library requires app config which needs to put in connection string, because this library actually connects with more than 1 database.

If i were to deploy to my database server, i would need to do encryption to my connection string for security purpose. I have read a lot of discussion in stack overflow, but most of them are using RsaProtectedConfigurationProvider which requires my database server to have IIS server to do decryption. But the case is my database server don't add in the IIS on windows component as it will requires opening a new port which means open a new thread towards the server.

So my challenge right now is to do encryption of my app config without using any of ASP.net encryption tools. Is there any other way for me to do the encryption?