Elliptic Curve Pairing for On-Demand Conditional Access Keys
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for pairing multimedia units with operators face delays in key delivery, vulnerability to theft, and inefficiencies due to the need for pre-delivery of cryptographic keys, which increases operational effort and risk.
Innovation Solution
A cryptographic pairing method using elliptic curve pairings, specifically exploiting the bilinearity property, allows for secure and efficient key generation between operators and multimedia units through the use of user and operator device identifiers, eliminating the need for pre-delivery of keys and reducing vulnerability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cryptographic keys are pre-delivered to the operator for all user devices, then the operator can activate user devices, but the delivery process takes several days and requires managing large quantities of keys
Solution Approach 1:
The patent segments the key management process by introducing operator-specific keys (KO) and device-specific keys (KD) that are generated on-demand rather than pre-delivered in bulk. Each operator-device pair receives its unique key pair through a pairing protocol that generates keys locally, eliminating the need for pre-delivery of all possible keys.
Solution Approach 2:
The system enables self-service key generation where the operator and user device autonomously generate their shared secret key through the pairing protocol without requiring manual key delivery from the operator to the device. The device can initiate pairing and receive keys through broadcast communication.
2Adaptability or versatility
If all cryptographic keys for all user devices are pre-delivered to the operator, then the operator can supply keys as requested, but the quantity of keys becomes very large and requires significant operational effort
Solution Approach 1:
The patent divides the key space into operator-specific components (KO) and device-specific components (KD) through the pairing protocol. Instead of managing a single large key for all devices, each operator-device pair generates its own segmented key pair, reducing the operational burden on the operator.
Solution Approach 2:
The pairing protocol serves multiple functions: it generates operator-specific keys, generates device-specific keys, establishes shared secrets, and enables conditional access control. This multi-functional approach replaces the need for separate key management processes.
3Ease of operation
If the user device is paired with the operator during initialisation at the final user premises, then the operator can personalize the device, but the operator must know the secret data which creates vulnerability to theft
Solution Approach 1:
The patent introduces a conditional access system as an intermediary that manages the key generation and distribution process. The conditional access system generates the operator-specific key and facilitates the pairing protocol without requiring the operator to store or transmit device-specific secret data, thereby reducing theft vulnerability.
Solution Approach 2:
The patent extracts the secret data requirement from the operator by implementing a pairing protocol where the operator only needs to provide public information (operator identifier) while the device provides its own secret (device key). The shared secret is generated through cryptographic pairing without the operator needing to know or store device secrets.
4Reliability
If the operator personalizes user devices through transmission system, then the operator can control content access, but the process requires tracing delivery and listing each device which causes delay
Solution Approach 1:
The patent enables the user device to initiate and perform its own personalization by broadcasting its device identifier and receiving the operator-specific key through broadcast communication. The device autonomously completes the pairing protocol without requiring the operator to manually trace or list devices, significantly reducing personalization delay.
Data Source
AI summary
A pairing method between a user device (1) and an operator device (2), the user device (1) being intended to receive conditional access data from the operator device (2), the user device having a user device identifier (UID), the operator having an operator device identifier (OID). The method comprises receiving, by the user device, a user device key (KUID) derived from a first cryptographically secure function and receiving, by the operator device, an operator key (KOID) derived from a second cryptographically secure function. The user device comprises a user device bilinear mathematical function (e(KUID, OID)) and the operator device comprises an operator bilinear mathematical function (e(UID, KOID)) which each define a pairing over an elliptic curve. The method includes generating, by the operator device (2), a pairing key (KD=e(UID, KOID)) between the user device (1) and the operator device (2), using the operator key (KOID) and the device identifier (UID) as variables of the operator mathematical function (e(UID, KOID)). The user device (1) generates the same pairing key (KD=e(KUID, OID)) using the user device key (KUID) and the operator device identifier (UID) as variables of the user device mathematical function e(KUID, OID).