Pseudonymous Hybrid Encryption via Sender-Specific Key Derivation

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Solution Overview

Problem

Hybrid encryption methods fail to preserve recipient pseudonymity as multiple senders can identify the recipient by comparing public keys, leading to potential exposure of personal data, and existing solutions require extensive computational resources and storage for generating and managing multiple key pairs.

Innovation Solution

A method where a recipient generates a public key based on a private key and a sender-specific basis, allowing each sender to derive a unique symmetric key for encryption, using an intermediate key and a secret, while only storing the private key, thus maintaining pseudonymity and optimizing resource usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a recipient uses a single public key for all senders in hybrid encryption, then key management is simplified, but the recipient's pseudonymity is compromised as senders can identify the recipient by comparing public keys

Engineering Contradiction:
Improvekey managementVSAvoidrecipient pseudonymity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention segments the public key into two components: a static first component (public key component) and a dynamic second component (ephemeral key). The static component remains constant for the recipient, while the dynamic component changes for each communication session or sender. This segmentation allows senders to encrypt messages using both components without exposing the static component, thereby preserving pseudonymity while simplifying key management.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces an intermediary mechanism where the static public key component is not directly used for encryption. Instead, it serves as a seed for generating dynamic ephemeral keys that are actually used for encryption. This intermediary layer protects the static component from exposure while still enabling secure communication.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a recipient generates multiple key pairs for different senders to preserve pseudonymity, then recipient pseudonymity is maintained, but computational resources and storage requirements increase significantly

Engineering Contradiction:
Improverecipient pseudonymityVSAvoidcomputational resources and storage
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The static public key component serves multiple functions: it acts as a seed for generating ephemeral keys for multiple different senders, provides a consistent identifier for the recipient across sessions, and enables key derivation without requiring separate key pairs for each sender. This universal component reduces both storage requirements and computational overhead while maintaining pseudonymity.

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

Solution Approach 2:

The recipient performs preliminary action by generating the static public key component once, which then serves as a foundation for all future communications. This preliminary key derivation eliminates the need to generate multiple complete key pairs, significantly reducing both storage requirements and computational resources while maintaining the ability to preserve pseudonymity through ephemeral key generation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3050244B1Provision and use of pseudonymous keys in hybrid encryption
Publication Date: 2019.03.20 BUNDESREPUBLIK DEUTSCHLAND
  • EP3050244B1 patent drawingFigure 1
  • EP3050244B1 patent drawingFigure 2
  • EP3050244B1 patent drawingFigure 3

AI summary

The invention relates to a method for providing pseudonymous keys for a hybrid encryption method and to a device, wherein the method comprises providing a public key for a sender, wherein the public key is generated on the basis of a private key and a sender-specific basis, receiving an intermediate key, wherein the intermediate key is generated by the sender on the basis of the sender-specific basis and a secret of the sender, and reconstructing a symmetric key on the basis of the intermediate key and the private key in order to decrypt a message encrypted by the sender by means of the symmetric key, wherein the symmetric key is generated by the sender on the basis of the public key and the secret of the sender. The invention further relates to a method for using pseudonymous keys in a hybrid encryption method, to a hybrid encryption method, to a sender, and to a system.