Memory Buffer Invalidation for Secure Data Access
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Solution Overview
Problem
Electronic devices, such as chip cards and control devices, face vulnerabilities in their memory storage systems that can be manipulated by attackers to access secret data or disrupt functionality, necessitating efficient protection mechanisms for memory contents.
Innovation Solution
A memory arrangement with a first buffer memory and its control unit that modifies memory contents during storage to invalidate them, and a second buffer memory and its control unit that checks for validity and reverses the modification upon reading, ensuring data integrity and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If memory contents are copied to a buffer memory for processing, then data access speed is improved, but security is worsened due to duplicate data presence enabling attacks
Solution Approach 1:
The patent changes the state parameter of the memory content by applying a reversible modification (such as XOR with a key or bitwise inversion) to the data in the original memory. This transformation maintains the data's functional integrity while changing its representational form, making it unreadable in its original form and thus preventing attacks that rely on accessing unmodified duplicate data.
Solution Approach 2:
The patent applies the reversible modification to the memory content before copying it to the buffer memory. This preliminary action ensures that the data is already in a protected, transformed state when it is duplicated, so that even though a copy exists in the buffer, the original in memory is rendered inaccessible in its usable form, thereby preventing security attacks.
2Reliability
If memory contents are invalidated by modification to prevent attacks, then security is improved, but data readability is worsened
Solution Approach 1:
The patent applies a reversible modification to the memory content that changes its state in a way that prevents direct reading and interpretation (improving security) while maintaining the capability to restore the original state through a known reversal operation (preserving readability). Examples include XOR with a secret key or bitwise inversion, where the same operation can both obfuscate and de-obfuscate the data.
Solution Approach 2:
The patent converts the potential harm of data modification (which could make data unreadable) into a benefit by using a reversible transformation. The modification appears to corrupt the data (making it unreadable to attackers), but because the modification is reversible through a known operation, the data remains readable and usable by authorized processes that know the reversal method.
3Reliability
If reversible modification is applied to maintain both security and readability, then security is improved, but device complexity is worsened due to additional control mechanisms
Solution Approach 1:
The patent implements a universal reversible modification mechanism that can be applied to any memory content regardless of its type or purpose. The same modification operation (e.g., XOR with a key) and the same reversal operation work for all data, instructions, and control information in the system. This multi-functionality reduces the need for different security mechanisms for different data types, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The patent enables the memory system to automatically apply and reverse the modification without requiring complex external control mechanisms. The buffer memory controller or memory management unit inherently knows how to apply the reversible modification when copying data and how to reverse it when needed, making the security mechanism self-managing and reducing the burden on external control systems.
Data Source
AI summary
A memory arrangement having a memory, a first buffer memory, a first buffer memory controller which, during the storage of memory contents from the memory in the first buffer memory, is configured to invalidate the memory contents in the memory by means of a modification, a second buffer memory and a second buffer memory controller which is configured to read memory contents from the memory, to check whether the memory contents read from the memory are valid and, if the memory contents read from the memory are invalid, to apply a reversal of the modification to the read memory contents.