Public Key Encryption for Hard Lock File Security

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Solution Overview

Problem

Existing public-key encryption algorithms, such as RSA PKCS #1 and ECIES, fail to securely encrypt large data streams or messages on locked devices, as the symmetric key remains accessible, violating the requirement that data should only be decryptable when the private key holder unlocks the device.

Innovation Solution

Implementing a method that uses a series of secret keys, where each key is deleted after use, and a one-way function to generate new keys from a shared secret, ensuring that only the private key holder can decrypt the data by discarding the shared secret and using a hash or KDF to derive encryption and authentication keys, thereby preventing unauthorized decryption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If hybrid symmetric/asymmetric encryption schemes (RSA PKCS #1, ECIES) are used to encrypt data, then encryption efficiency is improved, but the symmetric key remains accessible on the device, violating security requirements for locked devices

Engineering Contradiction:

Improveencryption efficiencyVSAvoiddata security

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent segments the encryption process into multiple discrete portions, where each portion is encrypted with a different secret key from a series of keys. This segmentation allows the system to maintain encryption efficiency while ensuring that no single key remains accessible for the entire data stream, thereby resolving the contradiction between efficiency and security.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a key discarding mechanism where each secret key is deleted after use to encrypt a specific portion of data. This discarding approach ensures that even if one key is compromised, only the corresponding data portion is vulnerable, while other portions remain secure with their respective discarded keys, thus maintaining overall data security without sacrificing encryption efficiency.

Inventive Principle:

Principle #34Discarding and recovering

2Speed

If the symmetric key is kept on the device for decryption, then decryption speed is improved, but the data becomes decryptable without the private key holder, violating security policies

Engineering Contradiction:

Improvedecryption speedVSAvoidaccess control

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent implements a dynamic key management system where secret keys are generated, used, and then discarded in sequence. This dynamic approach allows the system to maintain fast decryption speeds when needed while ensuring that keys are not persistently stored, thereby preventing unauthorized access and maintaining strict access control requirements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent treats secret keys as disposable, short-lived objects that are generated for specific encryption tasks and then discarded. This approach allows the system to achieve fast decryption performance when keys are available while ensuring that keys do not persist on the device, thus maintaining security policies that require private key holder authorization for data access.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If a series of secret keys are used to encrypt different portions of data, then security is improved, but key management complexity increases

Engineering Contradiction:

Improvedata securityVSAvoidkey management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a one-way function as an intermediary mechanism that generates a series of secret keys from a single shared secret. This intermediary approach improves data security by enabling multiple keys to be used while managing complexity through a centralized key derivation process, thus resolving the contradiction between enhanced security and simplified key management.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Adaptability or versatility

If the shared secret is retained for key derivation, then key generation flexibility is improved, but the possibility of unauthorized decryption increases

Engineering Contradiction:

Improvekey generation flexibilityVSAvoidunauthorized decryption risk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements preliminary action by deriving all necessary secret keys from the shared secret before the device is locked. This preliminary key generation ensures that the shared secret itself does not need to be retained on the locked device, thereby maintaining key generation flexibility while eliminating the risk of unauthorized decryption that would arise from retaining the shared secret on the device.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9825919B2Public key encryption algorithms for hard lock file encryption

Publication Date: 2017.11.21 MALIKIE INNOVATIONS LTD

AI summary

In some aspects, an encryption method comprises encrypting a first portion of a message using a first secret key. The first secret key is generated based on the public key of an entity. A one-way function is used to generate a second secret key from the first secret key, and the first secret key is subsequently discarded. A second portion of the message is encrypted using the second secret key. The encrypted first portion of the message and the encrypted second portion of the message are provided to the entity.