Secure Distance Measurement Using Transformed Spreading Codes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secure distance measurement systems using spreading codes are vulnerable to early detect late commit attacks, where an attacker intercepts and retransmits bit sequences to falsely reduce the measured distance, compromising security due to the long duration of spreading codes.
Innovation Solution
Transform the spreading code chip sequences using a shared transform function before transmission to prevent attackers from predicting the next chips, ensuring the integrity of the bit sequences and maintaining coding gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spreading codes are used to increase coding gain and robustness in noisy environments, then measurement reliability is improved, but the system becomes vulnerable to early detect late commit attacks due to the long duration of spreading codes
Solution Approach 1:
The patent applies dynamics by making the spreading code sequence variable and unpredictable through the use of a pseudo-random generator seeded with cryptographic keys. The code sequence changes dynamically for each challenge-response pair, preventing attackers from using static prediction strategies while maintaining the long duration needed for coding gain.
Solution Approach 2:
The patent changes the parameter of the spreading code from a fixed, predictable sequence to a dynamically generated pseudo-random sequence with high entropy. This is achieved by using cryptographic key derivation functions to generate unique code sequences for each authentication session, making early detection and prediction attacks computationally infeasible while preserving the code's robustness properties.
2Reliability
If spreading codes with long duration are transmitted to achieve coding gain, then robustness against noise is improved, but the time available for attack (t_short) increases
Solution Approach 1:
The patent applies preliminary action by pre-generating and securely storing a large pool of pseudo-random code sequences using cryptographic key derivation before the authentication process. During the actual measurement, the system quickly selects and applies a pre-prepared sequence, eliminating the need for real-time generation and ensuring the long duration is filled with unpredictable codes that cannot be anticipated by attackers.
Solution Approach 2:
The patent introduces a cryptographic pseudo-random generator as an intermediary between the authentication logic and the physical transmission medium. This intermediary transforms short cryptographic seeds into long, unpredictable code sequences, allowing the system to maintain high coding gain through long transmission durations while the cryptographic layer prevents attackers from predicting the actual code values.
3Reliability
If spreading codes are used to replace logical bits, then robustness in attenuated situations is improved, but the complexity of preventing attacks increases
Solution Approach 1:
The patent substitutes cryptographic mechanisms for traditional physical security measures. Instead of relying on hardware-based attack prevention or complex protocol designs, the system uses cryptographic key derivation and pseudo-random generation to provide security. This substitution simplifies the overall system architecture while providing strong security guarantees, as the cryptographic layer inherently prevents prediction and replay attacks.
Solution Approach 2:
The patent changes the fundamental parameter of code predictability by using cryptographic hash functions and key derivation algorithms. These mathematical transformations convert simple authentication secrets into complex, high-entropy code sequences that are computationally infeasible to predict or reverse-engineer, providing robust attack prevention without increasing hardware or protocol complexity.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Method for secure distance measurement comprising the following steps: transmitting from a verifier (V) to a prover (P) a challenge message comprising a challenge bit sequence (C); transmitting from the prover (P) to the verifier (V) a response message comprising the response bit sequence (R); verifying, in the verifier (V), the response message on the basis of the response bit sequence (R); and determining, in the verifier (V), the distance between the verifier (V) and the prover (P) on the basis of the time difference between the challenge message and the response message. The challenge message and/or the response message are transmitted by a transmission protocol in which the bit sequence (C, R) of the corresponding message is transmitted by a transformed spreading code chip sequence (TCSCS, TRSCS), wherein the transformed spreading code chip sequence (TCSCS, TRSCS) is obtained by transforming a spreading code chip sequence (CSCS, RSCS) of the bit sequence (C, R) on the basis of a transform function (ftrans).