Layered Video Stream Signatures for Pruning-Resilient Validation
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Solution Overview
Problem
Existing video surveillance systems face challenges in efficiently storing and verifying the integrity of encoded video streams, as pruning or malicious tampering can lead to loss of information and tampering detection methods are easily defeated, particularly when P- or B-frames are removed, resulting in reduced framerate and increased bitrate.
Innovation Solution
A method and system for providing digital signatures to a video stream encoded in layers, using a private-public key pair to encrypt signing data for each layer, allowing validation of the video stream independently of the number of received layers and enabling successive removal of layers while maintaining integrity verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If P- and B-frames are pruned to reduce storage space, then storage costs are reduced, but the framerate drops significantly and information is lost
Solution Approach 1:
The video stream is segmented into multiple layers with different frame rates and qualities. The base layer contains essential frames at lower framerate, while enhancement layers contain additional frames at higher framerate. This allows selective transmission and storage of layers based on available resources, reducing storage costs while maintaining the ability to reconstruct higher framerate video when needed.
Solution Approach 2:
The solution moves from a single-dimensional approach (pruning frames in a single video stream) to a multi-dimensional approach by creating layered video representations. Each layer operates at different temporal and quality dimensions, allowing the system to optimize storage by storing only essential base layer frames while enabling framerate restoration through layer combination when resources permit.
2Loss of information
If I-frames are transmitted more often to maintain framerate after pruning, then information loss is reduced, but bitrate increases significantly
Solution Approach 1:
The video data is segmented into base layer and enhancement layers. The base layer contains I-frames at lower rates, while enhancement layers contain additional frame data. This segmentation allows the system to transmit or store only the base layer when bandwidth or storage is limited, accepting some information loss, or combine layers when resources are available to reduce information loss without consistently increasing bitrate.
Solution Approach 2:
The system changes the parameter of frame transmission by using scalable video coding that allows dynamic adjustment of layer inclusion. Instead of fixed high bitrate transmission, the encoder can adaptively select which layers to transmit based on available bandwidth, changing the effective bitrate parameter while maintaining the ability to preserve video information when conditions permit.
3Reliability
If watermarking is implemented to verify video integrity, then tampering detection is enabled, but the method can be easily defeated
Solution Approach 1:
Cryptographic authentication data is generated and attached to the video stream at the encoding stage, before transmission or storage. This preliminary authentication allows receiving systems to verify integrity without requiring complex watermarking algorithms that can be defeated. The authentication is built into the video data structure itself, making tampering detection more robust.
Solution Approach 2:
The patent replaces the mechanical/optical watermarking system with a cryptographic authentication system. Instead of embedding detectable patterns in video frames that can be filtered or modified, the system uses cryptographic hashes and authentication codes that provide mathematically provable integrity verification, substituting a more robust computational mechanism for the vulnerable watermarking approach.
4Reliability
If all layers are validated to ensure complete integrity, then security is maximized, but validation complexity increases
Solution Approach 1:
The validation process is segmented into hierarchical levels corresponding to video layers. Each layer has its own authentication data that can be validated independently. This allows receivers to validate only the base layer when security requirements are minimal, or validate all layers when maximum security is needed, providing flexible complexity management while maintaining the ability to ensure complete integrity when required.
Solution Approach 2:
The system enables partial validation of only essential layers rather than requiring validation of all layers in all circumstances. The base layer validation provides sufficient security for many applications, while full multi-layer validation is available when higher security is needed. This partial action approach reduces validation complexity for typical use cases while preserving the capability for complete validation when security demands it.
Data Source
AI summary
There is provided techniques for providing digital signatures to a video stream encoded in layers. Each layer comprises encoded image frames. A digital signature for layer k=0 is provided by providing by generating signing data for layer k=0 and generating the digital signature for layer k=0. A respective digital signature for each layer k=1, . . . , K−1 is provided by, for each layer k=1, . . . , K−1 generating signing data, and generating the digital signature for layer k by encrypting the signing data, or a hash thereof, for layer k with the private key of the private-public key pair. The digital signatures for all the layers are provide to the video stream.