1. A computer-implemented method for authenticating a streamed transmission of a digital file, the method being performed by a system comprising a processor and a non-transitory computer-readable storage medium storing instructions that when executed by the processor, cause the system to perform the method, the method comprising; receiving a streamed transmission of a digital the and a progression of check values, each check value in the progression of check values being derived from at least one other check value in the progression and from a portion of the digital file, the progression of check values comprising an encrypted final check value corresponding to a beginning portion of the digital file and being included in proximity to a beginning of the streamed transmission; decrypting the encrypted final check value; determining the integrity of one or more portions of the digital file based, at least in part, on the decrypted final check value; and determining if the streamed transmission is authentic based on the determined integrity of the one or more portions of the digital file before the entire digital file is received.