Durable Cryptographic Keys via Backup Key Mediation

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Solution Overview

Problem

Existing solutions struggle to balance the durability and shreddability of cryptographic keys, making it difficult to ensure secure storage and recovery of keys while also allowing for their secure destruction, especially in complex computing networks.

Innovation Solution

A service provider offers an API for customers to backup and manage cryptographic keys through the generation of 'durable-until' keys, which are stored securely and can be used to restore 'shreddable' keys, with mechanisms for scheduled destruction to ensure key shreddability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cryptographic keys are stored durably for recovery, then key availability is improved, but key shreddability deteriorates

Engineering Contradiction:

Improvekey availabilityVSAvoidkey shreddability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The system performs preliminary actions by creating backup keys and storing them in secure locations before the original key is needed for shredding. This allows the system to recover from failures while maintaining the ability to shred keys when required, as the backup infrastructure is already in place and tested.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces backup keys as intermediary elements that mediate between the original cryptographic key and the recovery process. These backup keys are stored separately and can be used to restore access without requiring the original key to be permanently retained, thus enabling both durability and shreddability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If conventional delete operations are used, then key destruction is simplified, but key security deteriorates due to memory retention

Engineering Contradiction:

Improvekey destructionVSAvoidmemory retention

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system extracts the cryptographic key from the primary system memory and stores it in separate, secure backup locations. This extraction allows the key to be deleted from the main system while maintaining recoverability through the separated backup storage, eliminating the security risk of memory retention while preserving destruction capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs temporary key storage mechanisms where keys are held in volatile memory only for the duration needed for operations, then securely erased. The system accepts the cost of potential key loss in exchange for eliminating persistent security risks, using disposable key instances that are created, used, and destroyed in controlled cycles.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS10728031B2Durable cryptographic keys

Publication Date: 2020.07.28 AMAZON TECH INC

AI summary

Cryptographic keys are durably stored for an amount of time. A cryptographic key is encrypted so as to be decryptable using another cryptographic key that has a limited lifetime. The other cryptographic key can be used to decrypt the encrypted cryptographic key to restore the cryptographic key during the lifetime of the other cryptographic key. After the lifetime of the other cryptographic key, if a copy of the cryptographic key is lost (e.g., inadvertently and unrecoverably deleted from memory), the cryptographic key becomes irrecoverable.