Block Cipher Key Rotation Based on Adversarial Storage Limits

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Solution Overview

Problem

Traditional cryptographic key rotation techniques are based on computational power, which may not accurately represent an adversary's ability to corrupt a secure system, leading to unnecessary key replacements that waste computer resources.

Innovation Solution

Determine a key rotation period based on adversarial storage limit, generating cryptographic keys accordingly to ensure secure system maintenance without excessive resource usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a block cipher-based encryption scheme is used to protect sensitive data, then data security is improved, but the key rotation process becomes complex and time-consuming

Engineering Contradiction:

Improvedata securityVSAvoidkey rotation process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The key rotation process is segmented into distinct phases: generating a first encryption key for initial data protection, encrypting the first key to create a second key, and using the second key for subsequent data protection. This segmentation allows systematic management of key rotation complexity while maintaining continuous security.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by generating and encrypting the first encryption key before actual data encryption begins. The first key is encrypted using a key encryption key to produce a second key that will be used for data encryption, preparing the key rotation mechanism in advance to simplify the overall process.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If frequent key rotation is performed to maintain security, then security reliability is improved, but processing time and system overhead increase

Engineering Contradiction:

Improvesecurity reliabilityVSAvoidkey rotation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent implements periodic key rotation where encryption keys are systematically replaced at defined intervals or under specific conditions. The system rotates from a first encryption key to a second encryption key through a structured process, enabling security maintenance without continuous key changes that would consume excessive time.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If multiple encryption keys are managed for different data sets, then security coverage is improved, but key management complexity increases

Engineering Contradiction:

Improvesecurity coverageVSAvoidkey management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a universal key management approach where a key encryption key serves multiple functions: it encrypts the first encryption key to generate the second key, and it can be used consistently across different data sets and encryption operations. This multi-functionality reduces the need for separate key management systems for each data set.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3871363B1Computing key rotation period for block cipher-based encryption schemes system and method

Publication Date: 2026.05.20 VISA INTERNATIONAL SERVICE ASSOCIATION

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AI summary

A method including obtaining, by a key management computer, a key rotation period based on at least an adversarial storage limit. The key management computer can then generate a first cryptographic key. The key management computer can then generate a second cryptographic key to replace the first cryptographic key according to the key rotation period.