Content integrity and incremental security

摘要

A media signer produces an array of hash values including a respective hash value for each of multiple different portions of content. The media signer applies a hash function and an encryption key to the array of hash values to create a digital signature associated with the content. Prior to playback of the content, a media verifier retrieves the array of hash values for the different portions of content. The media verifier produces a hash value result for the retrieved array. Based on the hash value result for the retrieved array and a hash value result of the array in the received digital signature, the media verifier verifies the integrity of the retrieved array. If the retrieved array of hash values is found to be trustworthy, the media verifier determines the integrity of a portion of the content by verifying the portion's corresponding hash value from the “trustworthy” array.

主权项

1. A method comprising:
receiving, by a computing device, an array of hash values for respective portions of content, each of the portions being individual pages of a document or individual segments of audio or visual data; applying, by the computing device, a hash function to the array of hash values to produce a hash value result for the array; verifying, by the computing device, an integrity of the received array of hash values based on the hash value result produced for the received array of hash values; and based on verifying the integrity of the received array of hash values:
retrieving a first portion of the content and a second portion of the content;displaying the first portion of the content based on determining that a first hash value result generated by applying a hash function to the first portion of the content is equal to a first hash value from the array that corresponds to the first portion of the content; andpreventing display of the second portion of the content based on determining that a second hash value result generated by applying a hash function to the second portion of the content is different from a second hash value from the array that corresponds to the second portion of the content.