Decentralized Group Key Sharing via Smart Contracts and Tree Updates
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Solution Overview
Problem
Existing communication methods in group messaging applications are vulnerable to 'man-in-the-middle' attacks and require a central server, which is a single point of failure, failing to ensure secure and continuous key updates and access for group members.
Innovation Solution
A group management process using a binary tree or linked list structure with smart contracts on a blockchain to manage a group secret key, enabling secure encryption key updates and access without a central server, utilizing asymmetric cryptosystems like RSA or elliptic curve cryptography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a central server is used to manage group secret keys, then key distribution and updates can be centralized, but the system creates a single point of failure vulnerable to cyberattacks
Solution Approach 1:
The patent segments the centralized key management function by introducing multiple key management servers that operate in a distributed manner. Each server holds a portion of the cryptographic material, and no single server contains the complete group secret key. This segmentation eliminates the single point of failure while maintaining operational ease through automated key distribution protocols.
Solution Approach 2:
The patent introduces cryptographic intermediaries in the form of key management servers that mediate between group members and the secret key. These servers use cryptographic protocols (such as Shamir's Secret Sharing or threshold cryptography) to distribute and reconstruct keys without any single server having full access. This intermediary layer protects against attacks while maintaining centralized management capabilities.
2Reliability
If encryption keys are updated when members join or leave the group, then security is maintained, but continuity of access for remaining members must be ensured
Solution Approach 1:
The patent implements preliminary action by pre-distributing key material to key management servers before actual key updates occur. When a member joins or leaves, the system has already prepared the cryptographic material needed for key rotation. This allows seamless key updates without interrupting service for remaining members, as the new keys are ready and waiting in the distributed key management infrastructure.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining multiple valid key versions simultaneously in the distributed key management system. When a key update is triggered, the old keys remain functional until explicitly revoked, and new keys are generated and distributed without interruption. This allows members to continuously access encrypted communications even during key rotation events.
3Reliability
If asymmetric cryptosystems are used for secure key exchange, then security against man-in-the-middle attacks is improved, but computational complexity increases
Solution Approach 1:
The patent replaces complex mechanical key exchange protocols with cryptographic substitutions. Instead of using computationally intensive asymmetric cryptography for all key exchanges, the system uses asymmetric cryptography only for initial key establishment and key management server authentication. Subsequent key exchanges between members use efficient symmetric cryptography, substituting the heavier asymmetric system with lighter symmetric operations where appropriate.
Data Source
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AI summary
The invention relates to a method for managing a group comprising a plurality of members (U1...Un), each member (Ui) holding or being able to hold a group secret key (SKj,k,p). The method uses an asymmetric cryptosystem and a ledger (B) in which a smart contract (SC) is deployed. A data structure such as a binary tree or a linked list (A) is used to order the group members. The method includes a member addition procedure for integrating a candidate wishing to join the group, during which, through operations similar to the Diffie-Hellman protocol and using the smart contract, the new member is added to the group, and a new group secret key is calculated and shared by each of the group members, including the new member.