Host Device Cache Bypass for Virtual File Access

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Solution Overview

Problem

When a host device with a cache attempts to access a virtual file stored in a storage device's private memory area, it may return static content instead of different content as intended, due to the cache storing previously retrieved data, leading to unauthorized access and playback of the same content repeatedly.

Innovation Solution

Implementing a server within the host device, such as an HTTP server, to bypass the cache by sending requests directly to the storage device's private memory area, ensuring that each access to the virtual file retrieves new content from the storage device, thereby preventing cache-based errors and ensuring authorized access to different content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the host device uses a cache to store previously retrieved data, then access speed is improved, but content security deteriorates because the cache returns static content instead of different content from the private memory area

Engineering Contradiction:
Improveaccess speedVSAvoidcontent security
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent extracts the caching function from the host device's normal file access path by introducing a dedicated cache management component that intercepts and controls cache operations. This component monitors file access requests, identifies when cached data should be returned versus when fresh data from the private memory area is required, and manages the cache accordingly. This allows the cache to operate for performance while a security layer ensures content integrity by preventing unauthorized static content return.

Inventive Principle:
Principle #2Taking out (Extraction)

2Productivity

If the host device accesses the virtual file through the cache, then access efficiency is improved, but the ability to retrieve different content deteriorates

Engineering Contradiction:
Improveaccess efficiencyVSAvoidcontent retrieval capability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent implements a feedback mechanism where the cache management component continuously monitors file access patterns, cache hit rates, and content change indicators from the private memory area. Based on this feedback, the system dynamically adjusts cache behavior - maintaining aggressive caching when content is static and stable, but invalidating or bypassing the cache when content changes are detected or when security requirements demand fresh data retrieval. This feedback loop enables the system to balance efficiency and adaptability based on real-time conditions.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If the host device allows authenticated access to the private memory area, then authorized content access is enabled, but vulnerability to malicious software deteriorates

Engineering Contradiction:
Improveauthorized content accessVSAvoidmalicious software vulnerability
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a cache management component and security layer as an intermediary between the authenticated host application and the private memory area. This intermediary acts as a trusted mediator that verifies the legitimacy of access requests, monitors for malicious behavior patterns, and controls the flow of data between the host and secure storage. Even when authentication succeeds, the intermediary ensures that access follows security protocols, preventing malicious software from exploiting authenticated access to compromise content security.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2572309B1Host device and method for accessing a virtual file in a storage device by bypassing a cache in the host device
Publication Date: 2015.01.07 WESTERN DIGITAL ISRAEL LTD
  • EP2572309B1 patent drawingFigure 1
  • EP2572309B1 patent drawingFigure 2
  • EP2572309B1 patent drawingFigure 3A

AI summary

A host device is provided comprising an interface configured to communicate with a storage device having a public memory area and a private memory area, wherein the public memory area stores a virtual file that is associated with content stored in the private memory area. The host device also comprises a cache, a host application, and a server. The server is configured to receive a request for the virtual file from the host application, send a request to the storage device for the virtual file, receive the content associated with the virtual file from the private memory area of the storage device, wherein the content is received by bypassing the cache, generate a response to the request from the host application, the response including the content, and send the response to the host application. In one embodiment, the server is a hypertext transfer protocol (HTTP) server. In another embodiment, the server can determine if a request is associated with a normal user permission or a super user permission, and send a response to the host application only if it is determined that the request is associated with the normal user permission.