1. A computer-implemented method comprising: storing, by a computing device, an assignment blacklist and a sharing blacklist, the assignment blacklist including fingerprints identifying content items that are prohibited from being assigned to a user account, the sharing blacklist identifying content items that are prohibited from being shared from a user account; receiving a content item request associated with a first content item; determining a request type corresponding to the first content item request, where the request type is an assignment request or a share request, wherein the assignment request is a request to assign the first content item to a particular user account, wherein the share request is a request to share the first content item from the particular user account; generating, by the computing device, a first content item fingerprint from the first content item, the first content item fingerprint identifying the first content item; selecting the assignment blacklist when the request type is an assignment request; selecting the sharing blacklist when the request type is a share request; determining that the first content item fingerprint is included in the selected blacklist; and denying the content item request when the first content item fingerprint is included in the selected blacklist.