Encrypted Conversation History Access with Chained Secret Keys
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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 message keys, making it difficult for users to access the history without compromising security or memory usage.
Innovation Solution
A method where client devices generate secret keys by hashing message keys and upload key ciphertexts to a server, allowing target users to decrypt conversation history using a single secret key, reducing processing power and memory consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different message keys are used to encrypt different parts of the conversation, then security is improved, but the complexity of granting selective access increases
Solution Approach 1:
The patent introduces a key ciphertext as an intermediary element that bridges the gap between different message keys and the target user. Instead of directly managing multiple message keys, the system encrypts each message key with a unique key ciphertext that can be decrypted by the target user using their master key. This intermediary layer simplifies the access grant mechanism while preserving the security benefits of multiple message keys.
Solution Approach 2:
The patent segments the encryption scheme into distinct layers: message keys for encrypting conversation parts, key ciphertexts for securing message keys, and a master key for the target user. This segmentation allows the system to maintain multiple message keys for security while using a unified master key for selective access control, reducing the complexity of managing keys across different conversation segments.
2Ease of operation
If extensive processing and memory are used to decrypt conversation history, then access capability is improved, but resource consumption increases
Solution Approach 1:
The patent performs preliminary encryption of message keys with key ciphertexts before the target user needs to access the conversation history. This pre-computed key ciphertext is stored and can be quickly retrieved and decrypted by the target user using their master key, eliminating the need for extensive real-time processing to derive message keys during the access operation.
Solution Approach 2:
The patent creates a copy of the message key encrypted under a different key (the key ciphertext) that can be independently managed and decrypted. This copied encrypted form allows the target user to access conversation history without needing to perform complex decryption operations, as the key ciphertext serves as a ready-to-use encrypted version that simplifies the access process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables quick and secure selective access to encrypted conversation history by minimizing the need for extensive processing and memory usage while maintaining security, even when different message keys are used.
Implementation Method 1
determining a current secret key by hashing the prior secret key and the message key
Implementation Method 2
generating the key ciphertext by encrypting the prior secret key and the message key using the current secret key
Data Source
AI summary
Selective access to an encrypted conversation history can be granted as described herein. For example, a first client device can determine a message key used to encrypt messages associated with a conversation. The first client device can then generate a key ciphertext by: determining a prior secret key, determining a current secret key by hashing the prior secret key and the message key, and generating the key ciphertext by encrypting the prior secret key and the message key using the current secret key. The first client device can then transmit the key ciphertext to a server system. To grant the second client device with access to the encrypted messages, the first client device can transmit the current secret key to the second client device, which can obtain the key ciphertext from the server system and apply the current secret key to derive the message key and decrypt the messages.