Multistage Secure Boot Using Precomputed Firmware Authentication Tags

Solution Overview

Problem

Conventional boot processes in computing devices, particularly those with multiple hardware components, are inefficient and time-consuming due to the need for multiple asymmetric cryptographic calculations, which are processor-intensive and increase boot time and power consumption.

Innovation Solution

Implement a multistage boot process using independent stage keys, where authentication tags generated during a previous boot operation are used for faster symmetric cryptographic authentication of firmware images, reducing the need for repeated asymmetric cryptographic operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple asymmetric cryptographic calculations are performed to authenticate firmware during boot, then security is improved, but boot time increases

Engineering Contradiction:

Improvefirmware authentication securityVSAvoidboot time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The boot process is divided into multiple stages, with each stage having its own dedicated key (stage key). This segmentation allows the system to use different cryptographic approaches for different boot stages, optimizing both security and performance. The first stage key is used for initial authentication, while subsequent stages use their own keys, avoiding repeated asymmetric calculations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Authentication tags are generated in advance during previous boot operations and stored for later use. These pre-computed authentication tags eliminate the need to perform full asymmetric cryptographic calculations during each boot, as the system can verify firmware using the pre-generated tags with faster symmetric operations.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If multiple asymmetric cryptographic calculations are performed to authenticate firmware during boot, then security is improved, but power consumption increases

Engineering Contradiction:

Improvefirmware authentication securityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The boot process is divided into multiple stages, with each stage having its own dedicated key (stage key). This segmentation allows the system to use different cryptographic approaches for different boot stages, optimizing both security and performance. The first stage key is used for initial authentication, while subsequent stages use their own keys, avoiding repeated asymmetric calculations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Authentication tags are generated in advance during previous boot operations and stored for later use. These pre-computed authentication tags eliminate the need to perform full asymmetric cryptographic calculations during each boot, as the system can verify firmware using the pre-generated tags with faster symmetric operations.

Inventive Principle:

Principle #10Preliminary action

3Loss of time

If symmetric cryptographic operations are used instead of asymmetric operations, then boot time is reduced, but authentication security may be compromised

Engineering Contradiction:

Improveboot timeVSAvoidauthentication security

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

Authentication tags are generated in advance during previous boot operations and stored for later use. These pre-computed authentication tags eliminate the need to perform full asymmetric cryptographic calculations during each boot, as the system can verify firmware using the pre-generated tags with faster symmetric operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Authentication tags serve as intermediaries between the asymmetric cryptographic operations (performed once during previous boots) and the current boot verification process. These tags enable fast symmetric verification while maintaining the security guarantees of the original asymmetric authentication, acting as a secure mediator that preserves authentication integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12625967B2Multistage device boot with independent stage keys where first authentication tag is generated during previous boot operation

Publication Date: 2026.05.12 QUALCOMM INC

AI summary

Disclosed are systems, apparatuses, methods, and computer-readable media for booting a device with independent stage keys. In one illustrative example, a computing device can generate a first stage key for a first stage of a current boot operation of the device based on a private key associated with the device. The computing device can authenticate a first firmware of the first stage using a first authentication tag and the first stage key, wherein the first authentication tag is generated during a previous boot operation. computing device can execute the first firmware based on authenticating the first firmware.