Offline Device Authentication Using Ephemeral Key Pairs
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Solution Overview
Problem
Existing identity authentication systems face challenges in securely communicating sensitive information between devices, especially when one device is offline, as they rely on static secret keys and cannot encrypt data without prior contact.
Innovation Solution
The system employs asymmetric cryptography using ephemeral key pairs and Elliptic Curve Diffie Hellman (ECDH) for key agreement, allowing secure communication by transmitting a data stream with unencrypted and encrypted portions to authenticate and encrypt data even when one device is offline, using session keys generated through ECDH operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static secret keys are used for encryption, then key management is simplified, but security is compromised when devices are offline
Solution Approach 1:
The patent transitions from static secret keys to dynamic ephemeral key pairs that are generated and exchanged during the authentication process. The ECDH protocol enables devices to derive shared session keys dynamically without prior contact, resolving the contradiction by making key management adaptive rather than fixed, thereby maintaining security without excessive complexity
Solution Approach 2:
The patent performs preliminary key exchange actions through the ECDH protocol before actual data transmission. By establishing shared session keys in advance through mathematical operations on public keys, the system enables secure offline encryption without requiring continuous key management, thus improving security while simplifying operational complexity
2Reliability
If devices contact each other beforehand to establish encryption keys, then secure communication is enabled, but availability is reduced when devices are offline
Solution Approach 1:
The patent replaces the mechanical approach of direct device contact and manual key exchange with a mathematical substitution using ECDH protocol. This allows encryption key establishment through computational operations on public keys transmitted in data streams, enabling secure communication without physical or network contact between devices beforehand
Solution Approach 2:
The patent introduces mathematical operations (ECDH) as an intermediary mechanism between devices. Instead of devices needing to directly contact each other to exchange keys, the system uses cryptographic mathematics as a mediator that processes public keys to derive shared session keys, enabling offline secure communication while maintaining availability
3Ease of operation
If encryption keys are exchanged through data streams with unencrypted portions, then authentication is enabled, but data transmission security is reduced
Solution Approach 1:
The patent segments the data stream into distinct portions: unencrypted authentication data (for ease of operation) and encrypted data portions (for security). This segmentation allows the system to transmit authentication information openly while protecting sensitive data through encryption, resolving the contradiction between operational ease and data security
Solution Approach 2:
The patent applies different quality characteristics to different parts of the data stream. Unencrypted portions are used where authentication simplicity is critical, while encrypted portions are used where data protection is essential. This local differentiation of encryption quality allows the system to optimize both authentication ease and data security without compromise
Data Source
AI summary
A method of device authentication comprises transmitting a data stream from a first endpoint device to a second endpoint device. The data stream includes a first data stream portion including unencrypted data that includes an ephemeral public key of an ephemeral key pair, and an encryption algorithm identifier; a second data stream portion including encrypted data that includes a first counter value and an identity of the first endpoint device; and a third data stream portion including encrypted data that includes a second counter value and an identity of the second endpoint device. The method of device authentication further comprises the second endpoint device authenticating the first endpoint device using the first, second, and third data stream portions.