Logic Circuitry Packages Using Tokens to Limit Key Exposure
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Solution Overview
Problem
Existing authentication methods for logic circuits in print apparatus components, such as cartridges, are vulnerable to attacks and reverse engineering, particularly those using symmetric or asymmetric cryptography, which expose keys to unauthorized access and compromise security.
Innovation Solution
Implementing a logic circuitry package with a unique set of tokens stored in memory, where each token has a specific index and is used to authenticate the component, minimizing exposure of secret keys and requiring device-specific secrets, thus enhancing security by making it harder for attackers to emulate the logic circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If symmetric or asymmetric cryptography is used for authentication, then authentication functionality is provided, but security is compromised due to key exposure to unauthorized access
Solution Approach 1:
The patent extracts the secret key from the authentication process and replaces it with a challenge-response mechanism using tokens. The host logic circuit generates a challenge, the replaceable component processes it through its logic circuitry to produce a response, and authentication is completed without either party needing to store or transmit the actual secret key, thereby eliminating key exposure vulnerability
Solution Approach 2:
The patent introduces a challenge-response token mechanism as an intermediary between the host logic circuit and the replaceable component logic circuit. This intermediary process allows authentication to occur through mathematical transformations of challenges rather than direct key exchange, preventing unauthorized access to secret keys while maintaining authentication reliability
2Reliability
If logic circuits are made secure with authentication functions, then unauthorized access is prevented, but the logic circuits become vulnerable to attacks and reverse engineering
Solution Approach 1:
The patent segments the authentication system into multiple components: the host logic circuit, the replaceable component logic circuit, and the token-based challenge-response mechanism. This segmentation distributes security functions across multiple elements, making reverse engineering more difficult as an attacker would need to compromise multiple segmented components rather than a single centralized authentication module
Solution Approach 2:
The patent changes the fundamental parameter of authentication from static key storage to dynamic challenge-response token generation. By transforming the authentication mechanism from a static security model to a dynamic one where security credentials are generated on-demand through mathematical operations, the system becomes more resistant to reverse engineering as there are no static secrets to extract or analyze
3Reliability
If multiple tokens are stored in memory with specific indices, then device-specific authentication is enabled, but memory requirements and system complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-storing multiple tokens in the logic circuitry package memory during manufacturing, each associated with a specific index. These tokens are prepared in advance and can be rapidly retrieved and used for authentication without requiring complex real-time generation or management operations, thereby enabling device-specific authentication while keeping runtime complexity manageable
Data Source
AI summary
A logic circuitry package includes an interface to communicate with a host logic circuit and a logic circuit. The logic circuit is configured to store or generate a plurality of tokens corresponding to respective token indices. The logic circuit is configured to receive at least one challenge command from the host logic circuit including a subset of token indices. The logic circuit is configured to in response to the at least one challenge command, transmit a list of data including a subset of tokens of the plurality of tokens corresponding to the received subset of token indices.