A digital lock is a digital rights management (DRM) file encryption scheme designed designed to protect ebook files from copyright infringement. It monitors the various usages of the ebook, including downloads, loans and transfers to reading devices.

Currently, only about 2% of the publications in Cantook Hub are protected by a digital lock. The vast majority of publishers still prefer to use watermarks.

A digital lock is necessary when it comes to publications intended for digital lending in libraries. A time-sensitive lock mechanism allows granting a temporary licence for a given copy. After the designated period, the content becomes inaccessible (i.e. "locked") and the copy is made available for another patron. A digital lock also allows for early returns and extensions of digital library loans, when supported by the library.

A time-sensitive lock is a form of automated protection that renders an ebook unreadable on the loan due date.

Using a digital lock for loans is required and its application is enforced by Cantook Hub. However you can opt out of using a lock for sales to the general public.

There are several types of digital locks, including