Post-Quantum Session Resumption via Secret Reuse
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Solution Overview
Problem
Existing communication protocols face challenges in efficiently resuming encrypted sessions after an intervening period, particularly when using post-quantum ciphers, which are vulnerable to quantum computer attacks.
Innovation Solution
The method involves receiving a resumption message from a second computing system, decrypting it to obtain a resumption secret based on a shared secret from a prior post-quantum cipher handshake, and using this secret to encrypt messages for resumed sessions, thereby reusing the entropy of initial post-quantum computations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full handshake is performed to resume communication, then security is maintained, but latency and computing cost increase
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing cryptographic materials (secret blocks, public keys) during the initial handshake sequence. When resuming communication, these pre-computed materials are reused instead of performing full handshake computations again, thereby reducing latency while maintaining security through the use of previously established cryptographic parameters
2Reliability
If traditional encryption keys are used, then classical computing security is maintained, but quantum computing attacks succeed
Solution Approach 1:
The patent applies parameter changes by transitioning from traditional encryption parameters to post-quantum cryptographic parameters. It uses lattice-based cryptography with specific mathematical structures (modules, polynomials, error distributions) that are believed to be resistant to quantum attacks, thereby changing the fundamental cryptographic parameters to achieve quantum resistance while maintaining functional equivalence
3Reliability
If post-quantum ciphers are used for every session, then quantum resistance is achieved, but computational cost increases
Solution Approach 1:
The patent applies segmentation by dividing the cryptographic materials into distinct blocks (first secret block, second secret block, third secret block) with different purposes. The first block is used for key generation, the second for encryption, and the third for authentication. This segmentation allows selective reuse of different blocks during session resumption, reducing computational cost while maintaining quantum resistance where required
Data Source
AI summary
An example method is provided for resuming a communication session encrypted using a post-quantum cipher. The example method can include receiving, by a first computing system, a resumption message from a second computing system. The example method can include decrypting, by the first computing system, the resumption message to obtain a resumption secret, wherein the resumption secret is based on at least a portion of a shared secret that was obtained using a post-quantum cipher during a prior handshake sequence between the first computing system and the second computing system. The example method can include encrypting, by the first computing system, one or more messages using a session key based on the resumption secret. The example method can include sending, by the first computing system, the encrypted one or more messages to the second computing system.