A system may be configured to receive an upload, from a first user device, of a basis content item that includes first content; determine whether a first user of the first user device has a right to restrict a use of the first content in an in-use content item uploaded by a second user device when the in-use content includes the first content; in response to determining that the first user has the right, store the basis content in the system; in response to determining that the first user does not have the right, discard the basis content; receive an upload, from a second user device, of a first in-use content item; and determine whether the first in-use content item matches the basis content item.