EEPROM Counter Segmentation for Replay Attack Resistance
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Solution Overview
Problem
Current access security systems for automotive technology rely exclusively on base station-provided random numbers for cryptographic signature calculation, limiting cost-effectiveness and attack resistance, particularly against replay attacks, and require special hardware.
Innovation Solution
A software-based cryptographic authentication method using counter values stored in EEPROM segments for generating changing codes, optimizing write cycles and providing error recognition and correction, without the need for special hardware, thereby enhancing security and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hardware-software solutions with special hardware are used for cryptographic authentication, then attack resistance is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces hardware-based random number generators with a software-based counter mechanism stored in EEPROM. The counter value serves as the changing input for cryptographic signature calculation, eliminating the need for special hardware while maintaining security against replay attacks.
Solution Approach 2:
The patent uses standard EEPROM memory cells that can be programmed multiple times to store counter values. This approach uses inexpensive, readily available components instead of costly specialized hardware, achieving the same security function through software and standard memory.
2Reliability
If EEPROM segments are used for storing counter data with redundant information, then authentication security is improved, but the number of permitted write cycles decreases
Solution Approach 1:
The patent divides the authentication process into three phases using three EEPROM segments, allowing the system to cycle through segments and perform write operations on only one segment at a time. This segmentation distributes wear across multiple segments, extending the overall lifespan of the EEPROM memory.
Solution Approach 2:
The patent implements periodic write operations by cycling through three EEPROM segments in sequence. Each segment is written to only once every three authentication cycles, reducing the frequency of write operations on any single segment from every cycle to one-third of the cycles, thereby tripling the permitted write cycles.
3Device complexity
If base station provides all random numbers for cryptographic signature calculation, then device complexity in transponder is reduced, but attack resistance to replay attacks decreases
Solution Approach 1:
The patent pre-stores counter values in EEPROM segments before authentication occurs. These counter values are incrementally updated and used to generate changing cryptographic signatures, providing built-in protection against replay attacks without requiring complex real-time random number generation hardware in the transponder.
Data Source
AI summary
The invention relates to a method for cryptographic authentication in access security systems. The aim of the invention is to provide a software solution. To this end, the method for secured storage of counter states in a non-volatile memory (EEPROM) (10) involves an incrementing (11) process, and the current counter state is updated in only one EEPROM segment following each incrementing process (11), a subsequent access to the EEPROM (10) only being enabled in the event of a successful incrementing (11) of an EEPROM-based counter.