Bootloader Key Exchange for Encrypted Boot Volumes

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Solution Overview

Problem

Current boot mechanisms rely on unencrypted bootloader and OS kernel, making them vulnerable to tampering and requiring interactive user input or insecure network communication for encryption, which poses a security risk.

Innovation Solution

A method involving a Diffie-Hellman key exchange between a computing device and a remote server to decrypt an encrypted boot volume, allowing the bootloader to obtain an encryption key without user interaction, using DHCP PXE options for secure key exchange over an insecure network.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bootloader and OS kernel are stored in clear (unencrypted) form, then the system can boot without requiring user interaction or secure network communication, but the security of the boot data is compromised and it can be read or tampered with

Engineering Contradiction:
Improvesecurity of boot dataVSAvoidboot process simplicity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The encryption keys are exchanged and boot data is encrypted in advance before the boot process begins. The bootloader retrieves pre-shared encryption keys through DHCP/PXE protocols and decrypts encrypted boot data (kernel, initrd) during the boot process, eliminating the need for user interaction while maintaining security throughout the boot sequence

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces encryption keys and decryption mechanisms as intermediaries between the secure storage of boot data and its execution. The bootloader acts as an intermediary that retrieves encryption keys through network protocols, decrypts the boot data, and then transfers control to the kernel, thereby enabling both security and automated operation

Inventive Principle:
Principle #24Intermediary (Mediator)

2Extent of automation

If encryption keys are stored in a clear/non-encrypted area on the volume, then the boot process can proceed without user interaction, but the keys become vulnerable to being read and compromised

Engineering Contradiction:
Improveautomatic key provisionVSAvoidkey exposure risk
Core Design Contradiction:
Extent of automationVSObject-affected harmful factors

Solution Approach 1:

Encryption keys are exchanged and established in advance through secure key management protocols (DHCP/PXE) before the actual boot data decryption occurs. The keys are used immediately for decryption and then effectively discarded, preventing their long-term storage in vulnerable locations while enabling automated operation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system performs self-service key management by automatically retrieving encryption keys through network protocols during the boot process without requiring user interaction. The bootloader itself handles the key retrieval, decryption, and security management, eliminating the need for manual key provision while maintaining security

Inventive Principle:
Principle #25Self-service

3Reliability

If the OS kernel and dependent files are encrypted, then the security of the system is enhanced, but the bootloader cannot load them without first decrypting them, requiring additional key management mechanisms

Engineering Contradiction:
Improvesystem securityVSAvoidkey management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs universal encryption key management mechanisms that work across multiple components (bootloader, kernel, initrd) through standardized protocols. The same key exchange and decryption infrastructure is used for all encrypted boot data, reducing overall complexity despite encrypting multiple components

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The bootloader serves as an intermediary that manages the decryption of encrypted kernel and initrd files using keys retrieved through network protocols. This centralized key management approach in the bootloader simplifies the overall system by consolidating security operations in a single component rather than distributing complexity across multiple components

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Ensures secure and uninterrupted boot process by encrypting the OS kernel and bootloader, eliminating the need for clear storage of encryption keys and enhancing security by using secure key management.

Implementation Method 1

performing, as part of a boot process of a computing device, a key exchange with a server, to obtain a key

Methodology Applied
Scientific EffectDiffie-Hellman key exchange:

Implementation Method 2

decrypting, with the key, an encrypted portion of a boot volume

Methodology Applied
Scientific EffectDecryption:

Data Source

PatentEP3568796B1Bootloader level encryption for system boot data
Publication Date: 2022.11.23 THALES DIS CPL USA INC
  • EP3568796B1 patent drawingFigure 1
  • EP3568796B1 patent drawingFigure 2
  • EP3568796B1 patent drawingFigure 3

AI summary

A method for decryption for system boot data, performed by a computing device is provided. The method includes performing, as part of a boot process of a computing device, a key exchange with a server, to obtain a key. The method includes decrypting, with the key, an encrypted portion of a boot volume, and continuing the boot process, using the decrypted portion of the boot volume.