An Efficient Hybrid Key Exchange Mechanism

2025-05-05

AI Summary

To address the high computational and communication overhead in multi-session concurrent key distribution—and the reliance of security on the collective strength of underlying key encapsulation mechanisms (KEMs)—this paper proposes CHOKE, a coding-based hybrid KEM. CHOKE synergistically integrates linear error-correcting codes with parallel KEM encapsulation to achieve, for the first time, *individual security*: the confidentiality of each output key depends only on the security of at least one constituent KEM. For concurrent distribution of $n$ keys, CHOKE reduces both communication and computation costs to $1/n$ of those of conventional serial schemes—attaining theoretical optimality. Under the realistic assumption that each underlying KEM is invoked at least once, we provide a rigorous security proof in the standard model. CHOKE supports arbitrary $n$ independent keys, requires no trusted third party, and significantly enhances the efficiency and robustness of hybrid encryption architectures.

Technology Category

• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Search and Optimization: Distributed Search
• Machine Learning: Mixture of Experts (MoE)

Application Category

• Security and Privacy: Applications of cryptography
• Responsible Web: Measurement, analysis, and circumvention of Web censorship
• Semantics and Knowledge: Methods to enhance, augment, integrate or synergize semantic models such as knowledge graphs and LLMs

Abstract

We present extsc{CHOKE}, a novel code-based hybrid key-encapsulation mechanism (KEM) designed to securely and efficiently transmit multiple session keys simultaneously. By encoding $n$ independent session keys with an individually secure linear code and encapsulating each resulting coded symbol using a separate KEM, extsc{CHOKE} achieves computational individual security -- each key remains secure as long as at least one underlying KEM remains unbroken. Compared to traditional serial or combiner-based hybrid schemes, extsc{CHOKE} reduces computational and communication costs by an $n$-fold factor. Furthermore, we show that the communication cost of our construction is optimal under the requirement that each KEM must be used at least once.

Problem

• Secure simultaneous transmission of multiple session keys
• Reduce computational and communication costs n-fold
• Achieve optimal communication cost with individual KEM use

Innovation

• Hybrid KEM encodes multiple keys securely
• Uses linear codes for individual key security
• Reduces costs by n-fold versus traditional schemes