Over the last decade, baseline indexing techniques have been refurbished under the code name "content fingerprinting" when deployed in the context of security applications. In the first part of the talk, the speaker will detail the collection of security-related applications where content fingerprints have been exploited, including IP theft detection, audience measurement, traffic monitoring, forgery detection, etc. In the second part, he will discuss the unique technical challenges raised by the presence of a possibly hostile adversary in the ecosystem.