Split-Key Cryptosystem for Secure Content Distribution
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Solution Overview
Problem
Current content delivery systems lack secure mechanisms for content providers to control and monitor the delivery of content through networks of content distributors, increasing the risk of unauthorized access and fraud, especially when multiple distributors are involved.
Innovation Solution
A split-key cryptosystem is implemented, where content is encrypted using a cipher algorithm and split-key algorithm to generate multiple encryption and decryption keys, ensuring that no single distributor can fully decrypt the content, and unique decryption keys are generated for each delivery, allowing the content provider to trace and monitor delivery securely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a content distributor uses a content protection system with direct control of encryption and decryption keys, then the content can be decrypted and delivered to consumers, but the security is compromised when the CDN is attacked by an unauthorized party who can directly access the keys
Solution Approach 1:
The encryption key is divided into multiple segments or shares that are distributed to different entities (content provider and content distributor). No single entity possesses the complete key, so even if the CDN is compromised, the unauthorized party cannot reconstruct the full key without collaborating entities. This segmentation resolves the contradiction by maintaining security while enabling controlled delivery.
Solution Approach 2:
A key management server acts as an intermediary between the content provider and content distributor. This server securely manages key segments, controls their distribution, and monitors access. The intermediary prevents direct access to keys by the CDN while still enabling legitimate content delivery, thus resolving the security vulnerability.
2Productivity
If multiple content distributors are involved in the delivery chain, then the content can be delivered to large groups of consumers, but the complexity of the delivery and billing process increases and the security may be compromised
Solution Approach 1:
The key management server provides universal functionality across the entire content delivery network, handling key distribution, access control, and monitoring for multiple distributors and consumers. This centralized multi-functional system reduces complexity by providing a single point of control rather than requiring separate security mechanisms at each distributor level.
Solution Approach 2:
The system implements feedback mechanisms where the key management server monitors and tracks content access across the distribution network. This feedback enables transparent billing and security monitoring, allowing the content provider to track content usage and detect unauthorized access, thereby managing complexity through information flow.
3Adaptability or versatility
If the content provider outsources content delivery to content distributors, then the content provider can reach more consumers, but the content provider loses direct control and monitoring capability over the secure delivery process
Solution Approach 1:
The key management server establishes feedback channels between the content provider and content distributors. The server reports content access events, delivery status, and security incidents back to the content provider, maintaining transparency and control. This feedback mechanism resolves the information loss while preserving distribution versatility.
Solution Approach 2:
The key management server serves as an intermediary that maintains the content provider's control capability without requiring direct involvement in each delivery transaction. The server enforces security policies, manages key distribution, and provides monitoring capabilities, allowing the content provider to outsource delivery while retaining oversight.
Data Source
AI summary
Methods and systems are described for secure delivery of a content item from at least a first content distribution network (CDN1) to at least one content receiving entity using a split-key cryptosystem comprising encryption and decryption algorithms E and D, a cipher algorithm for generating encryption and decryption keys e,d on the basis of secret information S and a split-key algorithm using secret information S for splitting e into i different split-encryption keys e1, e2, . . . , ei and/or for splitting d into k different split-decryption keys d1, d2, . . . , dk respectively, such that Ddk(Ddk-1( . . . (Dd2(Dd1(Eei(Eei-1( . . . (Ee2(Ee1(X)) . . . ))=Ddk(Ddk-1( . . . (Dd2(Dd1(Xe1, e2, . . . , ei))=X wherein i,k≧1 and i+k>2. The method may comprise: a content source providing said at least one CDN1 with at least one an encrypted content item Xe; a key generator associated with said content source comprising said cipher and split-key algorithm generating first split-key information and transmitting said first split-key information to said first CDN1, preferably to a first secure module associated with said CDN1; generating a partially decrypted content item on the basis of said encrypted content item Xe, said decryption algorithm D and said first split-key information; and, transmitting said partially decrypted content item to said content receiving entity.