How can we generate an encrypted pdf from Salesforce?

Hi Pranav,

you should be able to limit who can see your page by only adding specific profiles to the page.

From Setup, enter Visualforce Pages in the Quick Find box, then select Visualforce Pages.
Next to the name of the page that you want to restrict, click Security.
Select the profiles that you want to enable from the Available Profiles list and click Add.
Select the profiles that you want to disable from the Enabled Profiles list and click Remove.
Click Save.
From: https://help.salesforce.com/apex/HTViewHelpDoc?id=pages_security_page_def.htm&language=en_US

Thanks