Multi-Pulse Spreading Sequence Encryption for Secure Ranging

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Solution Overview

Problem

In Direct Sequence Spread Spectrum (DSSS) and Ultra-wideband (UWB) communication, the polarity of the first pulse of a multi-pulse sequence can reveal the polarity of the entire spreading codeword to attackers, allowing them to reproduce and transmit the remainder with a negative delay, compromising the security of communication and ranging systems.

Innovation Solution

The use of a device that creates and transmits a spreading sequence for subsequent packets, where the sequence is encrypted and varied per radio packet, shared through a cryptographic channel, and computed by the receiver using a secret key or table lookup, making it difficult for attackers to predict the remainder of the multi-pulse sequence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the first pulse of the multi-pulse sequence is transmitted with high signal-to-noise ratio, then the receiver can reliably detect the polarity of the spreading sequence, but attackers can observe and predict the entire spreading codeword from the first pulse alone

Engineering Contradiction:

Improvedetection reliabilityVSAvoidsecurity vulnerability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The spreading sequence is divided into two independent parts: a first spreading sequence transmitted in the clear for reliable detection, and a second spreading sequence transmitted in encrypted form for security. This segmentation allows each part to serve its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An encrypted channel acts as an intermediary to transmit the second spreading sequence. This intermediary protects the critical security information from attackers while still allowing the receiver to obtain it through the secure cryptographic channel.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the same spreading sequence is used for multiple packets, then the system operation is simplified, but attackers can more easily predict and reproduce the spreading codeword

Engineering Contradiction:

Improvesystem operation simplicityVSAvoidpredictability by attackers

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system dynamically changes the spreading sequence for each packet by combining a static first spreading sequence with a dynamic second spreading sequence that varies per packet. This dynamic approach maintains simplicity in transmission while preventing predictability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The receiver is pre-configured with both spreading sequences through secure channels before actual communication begins. This preliminary action allows the receiver to handle variable sequences without increasing operational complexity during transmission.

Inventive Principle:

Principle #10Preliminary action

3Object-affected harmful factors

If the spreading sequence is encrypted and varied per packet, then security against attackers is improved, but the system complexity increases

Engineering Contradiction:

Improvesecurity against attackersVSAvoidsystem complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the parameter of sequence variability from static to dynamic by introducing a second spreading sequence that varies per packet. This parameter change enhances security while maintaining manageable complexity through clear separation of concerns.

Inventive Principle:

Principle #35Parameter changes

4Quantity of substance

If only one spreading sequence is transmitted, then the transmission overhead is reduced, but the receiver cannot simultaneously achieve reliable detection and security

Engineering Contradiction:

Improvetransmission overheadVSAvoiddetection reliability and security

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The two spreading sequences work together to achieve multiple functions simultaneously: the first sequence provides detection reliability while the second sequence provides security. Together they form a comprehensive solution that addresses both requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10237056B2Multi-pulse communication using spreading sequences

Publication Date: 2019.03.19 NXP BV

AI summary

Various exemplary embodiments relate to a method of communicating by a transmitter. Embodiments of the method may include creating information to be used by a receiver to define a spreading sequence for a subsequent packet, coding the information into a current communications packet, and transmitting the current communications packet.