Printer Consumable Authentication Key Retrieval Limiting
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Solution Overview
Problem
Current authentication methods for consumables in printer systems are vulnerable to side-channel attacks, particularly differential power analysis (DPA) attacks, which can compromise the secret key and allow clone cartridges to be indistinguishable from authorized ones, leading to potential damage to the printing system and legal issues with unauthorized refills.
Innovation Solution
Implementing a QA device with a non-volatile memory for storing a base key, generating a variant key using a one-way function with printer-specific information, and limiting the number of base key retrievals to frustrate DPA attacks, while allowing legitimate use of cartridges across multiple printers without exceeding the retrieval limit, and using caching and masking operations to secure communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base key is stored in non-volatile memory for authentication, then the authentication security is improved, but the system becomes vulnerable to differential power analysis attacks that can extract the key through repeated retrievals
Solution Approach 1:
The patent implements dynamic behavior in key retrieval by introducing random delays and variable timing between key access operations. The QA device dynamically adjusts the timing characteristics of base key retrievals, making power consumption patterns unpredictable and thereby frustrating differential power analysis attacks that rely on consistent temporal patterns.
Solution Approach 2:
The patent changes the temporal parameters of key retrieval operations by introducing random delays and varying the timing intervals between successive key accesses. This parameter variation transforms the static, predictable retrieval pattern into a dynamic one with unpredictable timing, rendering DPA attacks ineffective.
2Object-affected harmful factors
If the base key retrieval is limited to frustrate DPA attacks, then the security against attacks is improved, but the ability to allow legitimate use across multiple printers may be restricted
Solution Approach 1:
The patent segments the key management functionality by introducing intermediate variant keys that are stored in volatile memory. These variant keys serve as proxies for the base key, allowing multiple authentication operations without requiring repeated retrievals of the base key from non-volatile memory. This segmentation enables both attack resistance and operational flexibility.
Solution Approach 2:
The patent introduces variant keys as intermediary elements between the base key and the authentication process. These intermediate keys are generated from the base key using a one-way function and stored in volatile memory, serving as mediators that enable multiple authentication operations without exposing the base key to repeated retrieval cycles that would trigger DPA vulnerability.
3Productivity
If caching mechanisms are implemented to improve performance, then the communication efficiency is improved, but the memory requirements and potential attack surface are increased
Solution Approach 1:
The patent extracts the caching functionality to apply selectively only to variant keys in volatile memory, not to the base key in non-volatile memory. This extraction approach caches frequently used intermediate values to improve performance while maintaining strict retrieval limits on the critical base key, thereby balancing efficiency gains with security constraints.
Data Source
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AI summary
A method, system and device for encrypted communication with external entities, then device being configured to frustrate side channel attacks attempting to determine an encryption key. The device has a first memory, an encryption key stored in the first memory and a one-way function for application to the encryption key. During use, the encryption key is retrieved from the first memory prior to application to the one-way function and the device is configured to limit the number of times the encryption key is allowed to be retrieved from the non-volatile memory to a pre-determined threshold.