Partial URL Signing for DASH Content Access Control
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Solution Overview
Problem
Dynamic Adaptive Streaming over HTTP (DASH) faces challenges in implementing URL signing for content access control, particularly with segment templates making it difficult to sign individual segments and distribute signed URLs efficiently, especially for live streaming content.
Innovation Solution
Partial URL signing is introduced, where signing information is provided as a query parameter in the form of a prefix, suffix, or substring of the URL, allowing verification and access control for individual segments within the Media Presentation Description (MPD), enabling efficient access control for DASH content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete URL signing is implemented for each content segment, then access control security is improved, but the complexity of distributing signed URLs for dynamic adaptive streaming increases significantly
Solution Approach 1:
The URL is segmented into a base URL portion and a query parameter portion. The base URL remains unsigned and is distributed through the MPD, while only the query parameters (containing expiration time, client identifier, and signature) are signed. This segmentation allows the signing mechanism to apply only to the access control-critical portions of the URL, reducing the overall complexity while maintaining security.
Solution Approach 2:
The signing information (expiration time, client identifier, and digital signature) is extracted as separate query parameters from the complete URL. This extraction allows the signing mechanism to operate independently on these specific parameters rather than the entire URL, simplifying the distribution process while preserving access control functionality.
2Reliability
If individual segment URLs are signed, then content protection is improved, but the efficiency of URL generation and access workflow is reduced
Solution Approach 1:
Instead of signing the entire URL or all possible segment URLs, the solution applies partial signing only to the query parameters that are essential for access control (expiration time, client identifier, and signature). This partial action approach maintains content protection while avoiding the excessive complexity of signing every possible URL variation in the adaptive streaming workflow.
3Measurement precision
If full URL signing with all query parameters is used, then access control precision is improved, but the overhead of signature verification and URL processing increases
Solution Approach 1:
The signing mechanism extracts and signs only the essential query parameters (expiration time, client identifier) rather than all possible URL parameters. This extraction reduces the data that needs to be signed and verified, lowering the computational overhead and processing time while maintaining precise access control through the essential parameters.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
A partial URL signing scheme for controlling access to content provided in adaptive streaming such as DASH is disclosed herein. Partial URL signing and verifying algorithms act as extensions to existing URL/URI signing techniques (e.g., IETF URI Signing). Partially signed URLs are signaled in an MPD and may take the form of a prefix, a suffix, or a substring of a URL. Individual segments of the content are requested by the client using URLs constructed based on a URL segment template with partial URL signing information provided as a query parameter for verification.