A system includes a registration server and an authentication server. The registration server receives a source video and splits it into a series of segments that includes a first segment. The registration server generates a first hash from the first segment and stores it in a block in a blockchain. The registration server stores an identifier for the block in the first set of metadata. The authentication server receives a request to authenticate a target video and splits it into a series of segments that includes a first segment, corresponding to the first segment of the source video. The authentication server generates a second hash from the first segment. The authentication server determines that the second set of metadata includes the identifier and uses it to locate the block in the blockchain. The authentication server determines that the second hash does not match the first hash and transmits an alert.