Ciphertext Tree Key Storage for Selective Conversation Access
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Solution Overview
Problem
Existing systems face challenges in efficiently and securely granting selective access to an encrypted conversation history, particularly when different parts of the conversation are encrypted with different keys.
Innovation Solution
A ciphertext tree is constructed using encryption keys, allowing for the selective granting of access by providing a derived key corresponding to an internal node or leaf node, reducing the need for extensive communication and resource consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional key storage methods are used for encrypted conversation history, then access control can be implemented, but processing power, bandwidth, and memory consumption increase significantly
Solution Approach 1:
The conversation history is divided into multiple segments, each encrypted with a different key and stored as a separate node in a ciphertext tree. This segmentation allows selective access to specific conversation segments without requiring the recipient to receive or process all encryption keys, thereby reducing bandwidth and processing power consumption while maintaining reliable access control.
2Ease of operation
If all encryption keys are provided to enable access to conversation history, then complete access is granted, but security is compromised for selective access scenarios
Solution Approach 1:
Different parts of the conversation history are encrypted with different keys, creating local quality variations in the encryption scheme. When granting access, only the specific keys corresponding to the desired conversation segments are provided to the recipient. This enables easy access granting for specific segments while maintaining security by not exposing all keys, as each key only decrypts its corresponding segment.
3Manufacturing precision
If extensive key management is implemented for selective access, then access control precision improves, but device complexity increases
Solution Approach 1:
A ciphertext tree structure is implemented where encryption keys are nested hierarchically. Each node in the tree contains a key that can decrypt its child nodes, creating a nested structure. This nesting enables precise selective access control by providing specific keys at different levels of the hierarchy, while the tree structure itself manages the complexity of key relationships, reducing the operational complexity for key management.
4Adaptability or versatility
If multiple encryption keys are stored for different conversation segments, then selective access is enabled, but memory usage increases
Solution Approach 1:
The ciphertext tree is constructed in advance with all encryption keys and ciphertexts organized in the hierarchical structure before access is needed. This preliminary organization allows the system to provide selective access by simply selecting and transmitting the specific keys required, without needing to dynamically generate or retrieve keys during access operations. The pre-organized structure enables versatile selective access while optimizing memory usage by only storing and transmitting necessary keys.
Data Source
AI summary
Tree-based key storage can be used to selectively grant access to an encrypted conversation history. For example, a system can access a ciphertext tree that includes an internal node with a set of child nodes. The internal node can correspond to a key and a ciphertext. The ciphertext can be generated by encrypting a set of child keys, corresponding to the set of child nodes, using the key. The set of child keys may have been used to encrypt messages associated with a conversation. The system can then provide the ciphertext to a client device. The client device can receive the key from a source, decrypt the ciphertext using the key to derive the set of child keys corresponding to the set of child nodes, and decrypt at least some of the encrypted messages using at least one key of the set of child keys.