Delegated Lock Access Using Derived Keys for Identity Privacy
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Solution Overview
Problem
Existing electronic locks with delegation capabilities do not adequately protect the privacy of the delegatee, as their identity can be tracked and exposed during access rights delegation.
Innovation Solution
A method and system using elliptic-curve cryptography to derive a temporary public key and secret key pair for the delegatee, ensuring the physical lock only verifies the derived key without knowing the delegatee's true identity, thereby maintaining privacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the delegatee's identity is exposed during access rights delegation, then the physical lock can verify the delegatee's identity, but the delegatee's privacy is compromised and tracking becomes possible
Solution Approach 1:
The delegatee's identity information is segmented into two components: a permanent identity (source public key) and a temporary derived identity (derived public key). The lock only receives and verifies the temporary derived identity, which is mathematically linked to but does not directly reveal the permanent identity. This segmentation allows verification while protecting privacy.
Solution Approach 2:
The derived public key acts as an intermediary between the delegatee's true identity and the physical lock. It serves as a mathematical mediator that enables the lock to verify the delegation's authenticity without exposing the delegatee's actual identity. The intermediary preserves verification capability while preventing direct identity exposure.
2Loss of information
If a temporary derived key is used for authentication, then the delegatee's privacy is protected, but the system complexity increases due to key derivation operations
Solution Approach 1:
The key derivation operations are performed in advance - the delegator derives the temporary public key from the source public key before creating the delegation, and the delegatee derives the temporary secret key from their source secret key. This preliminary action eliminates the need for complex real-time derivation during authentication, reducing operational complexity.
Solution Approach 2:
Instead of managing entirely new key pairs for each delegation, the system creates derived keys that are mathematical copies or transformations of the source keys. The derived public key is a transformation of the source public key, and the derived secret key is a transformation of the source secret key. This copying approach simplifies key management compared to generating completely independent keys.
Data Source
AI summary
It is provided a method for providing a privacy-enhanced delegated access right to unlock a physical lock. The method comprises: obtaining a derivation scalar; receiving a cryptographically signed delegation from the delegator device, the delegation being a data object comprising a public key of the delegator device, a public key of the physical lock, and a derived public key for the delegatee device, and wherein the delegation is cryptographically signed using a secret key that is paired with the public key of the delegator device; obtaining a source secret key for the delegatee device, the source secret key being paired with the source public key; calculating a derived secret key for the delegatee device using the source secret key for the delegatee device and the derivation scalar; providing the delegation to the physical lock; and authenticating the delegatee device with the physical lock using the derived secret key.