Ephemeral Entropy for Secure Logon Resumption

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Solution Overview

Problem

Existing systems require user credentials for access to resources during system reboots, which can be inconvenient and insecure, as they necessitate manual re-entry of credentials.

Innovation Solution

A method where a user device generates ephemeral entropy to encrypt and decrypt a data protection key, allowing access to user resources without requiring the actual user credential during reboots, by storing the ephemeral entropy in a secure location and using it to reestablish access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If user credentials are required during system reboot for resource access, then security is maintained, but user convenience deteriorates due to manual re-entry requirement

Engineering Contradiction:
ImprovesecurityVSAvoiduser convenience
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system performs preliminary actions by generating ephemeral entropy and encrypting the data protection key with this entropy before the reboot occurs. The encrypted key is stored in a secure location, so that upon reboot, the system can automatically decrypt and use the key without requiring manual credential entry, thus maintaining security while improving convenience.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If ephemeral entropy is generated and stored to enable automatic access, then ease of operation improves, but device complexity increases

Engineering Contradiction:
Improveautomatic accessVSAvoidsystem complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The system introduces ephemeral entropy as an intermediary element between the user credential and the data protection key. Instead of directly storing or requiring the user credential, the system uses the ephemeral entropy to encrypt and store the data protection key, creating a middle layer that enables automatic access while managing complexity through controlled entropy generation and secure storage mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If credential-protected key is decrypted and reencrypted with ephemeral entropy, then access security is maintained, but loss of time occurs during the reencryption process

Engineering Contradiction:
Improveaccess securityVSAvoidreencryption time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs the decryption and reencryption operation as a preliminary action before the reboot occurs. By completing the key transformation in advance and storing the entropy-protected key in a secure location, the system avoids the need to perform time-consuming cryptographic operations during the reboot process, thus maintaining security while minimizing time loss.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3289505B1Resumption of logon across reboots
Publication Date: 2019.04.03 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3289505B1 patent drawingFigure 1
  • EP3289505B1 patent drawingFigure 2
  • EP3289505B1 patent drawingFigure 3

AI summary

In one embodiment, a user device may reestablish access to a user resource while forgoing use of a user credential during a system reboot. The user device may receive the user credential from a user during an initial login to access the user resource. The user device may create an ephemeral entropy to access the user resource. The user device may access the user resource using the ephemeral entropy.