Precomputed Transactional Mixing for Anonymity
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Solution Overview
Problem
Existing mix networks in cryptographic systems are inefficient in terms of computation and delay, limiting their adoption and efficacy, and may be vulnerable to cryptanalytic attacks due to stronger assumptions about underlying cryptographic primitives.
Innovation Solution
A cascade of mix nodes processes messages using a combination of unpermuted and permuting phases with shared public keys for homomorphic encryption, reducing computation and delay while maintaining unlinkability and security through independent identity verification and pipelining of processing phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If public-key cryptographic processing is performed on messages as they travel through the mix network, then security and unlinkability are maintained, but computational overhead and processing delay increase significantly
Solution Approach 1:
The patent applies preliminary action by performing cryptographic processing in advance during message formation. Users encrypt messages with a composite public key before submitting them to the mix network, and the system pre-computes certain cryptographic parameters. This eliminates the need for intensive real-time cryptographic operations within the mix nodes, thereby maintaining security while significantly reducing processing delay and computational overhead.
2Reliability
If multiple stages of mixing are used to enhance privacy protection, then unlinkability improves, but cumulative delay increases and system complexity grows
Solution Approach 1:
The patent merges multiple cryptographic operations into a single composite public key that users obtain from the mix network. Instead of requiring separate cryptographic processing at each mix stage, the system combines the security benefits of multiple stages into one pre-computed key structure. This allows users to encrypt messages once with the composite key, achieving the unlinkability of multiple mixing stages while avoiding the cumulative delay of processing through each stage sequentially.
3Ease of manufacture
If stronger assumptions about cryptographic primitives are made to simplify the mixing protocol, then implementation becomes easier, but vulnerability to cryptanalytic attacks increases
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of a composite public key structure that mediates between security requirements and implementation simplicity. The mix network generates and manages this composite key that incorporates multiple cryptographic assumptions, allowing users to interact with a single simplified interface while the underlying complex cryptographic structure provides robust security. This intermediary absorbs the cryptographic complexity, maintaining both security and ease of use.
Data Source
AI summary
Precomputed and transactional mixing is believed to allow portable devices, such as smart phones, to send and receive messages, with little extra bandwidth or battery usage, while achieving anonymity for senders and recipients among all messages sent globally in batches defined by short time intervals. To learn anything about which inputs correspond with which outputs of such a batch of messages, the entire cascade of mix devices, each preferably operating independently in a different country, would it is believed have to be compromised.None of the real-time computation, neither by the mixes nor smartphones, uses full public-key operations—resulting it is believed in orders of magnitude performance improvement over previously-known systems.Aspects include untraceable return addresses, group chat, feed-following and large payloads. Transaction protocols include a variety of payments use cases. Limited anonymity and credential mechanism are based on a new approach to user identification disclosed, in which each user provides a small amount of different identifying information to each mix node, so that comparatively little is revealed to each node individually.