Accessing information from an encrypted file

[Ringside]

I would like to create a simple tab in excel that would calculate a quotation
using data input into that tab.
Excel would then calculate the pricing using constants contained in another
file that i would like to restrict access to. I attepted to passwork protect
and encrypt the file (that i would like to restrict access to) but then my
original cant access the data. I'm pretty sure there are 100 better ways
(even for a rookie) to do this...
I'll be grateful for any help that can be provided.

Thank you