Session Key Exchange Using Pseudonym IDs for Forward Unlinkability
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Solution Overview
Problem
Existing session key exchange protocols in the Internet of Drones (IoD) lack standard forward secrecy and forward unlinkability, allowing session keys to be compromised by drone-capturing attacks and exposing user anonymity.
Innovation Solution
A method for session key exchange between terminals using a simultaneous mutual key exchange protocol that involves determining pseudonym identifiers (PIDs), transferring cipher texts and MAC values, and establishing session keys based on hash functions and shared encryption keys to ensure forward secrecy and unlinkability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing session key exchange protocols are used in IoD, then communication between terminals can be established, but forward secrecy and forward unlinkability cannot be guaranteed, allowing session keys to be compromised by drone-capturing attacks
Solution Approach 1:
The protocol segments the key exchange process into distinct phases: initial key pair generation, ephemeral key exchange for session key derivation, and separate authentication phases. This segmentation allows each component to contribute to forward secrecy independently, ensuring that compromise of long-term keys does not reveal past session keys.
Solution Approach 2:
The protocol performs preliminary actions by generating ephemeral key pairs before the actual communication session and using these to derive session keys. The pseudonym identifiers are generated in advance based on these ephemeral keys, establishing forward secrecy before any sensitive communication occurs.
2Reliability
If existing session key exchange protocols are used in IoD, then communication between terminals can be established, but forward unlinkability cannot be guaranteed, exposing user anonymity
Solution Approach 1:
The protocol employs asymmetric cryptography with distinct key pairs for identity establishment and session key exchange. The pseudonym identifiers are derived asymmetrically from ephemeral keys rather than being directly tied to long-term identity keys, breaking the linkability between sessions while maintaining authentication.
Solution Approach 2:
Ephemeral key pairs serve as intermediaries between the long-term identity keys and the session keys. These ephemeral keys generate pseudonym identifiers that mediate the connection between communication parties without exposing the underlying identity, thereby ensuring forward unlinkability.
3Object-affected harmful factors
If a drone is captured, then the attacker can access stored keys, but with this protocol the session keys from previous sessions remain protected through forward secrecy
Solution Approach 1:
Ephemeral key pairs are generated in advance of each session, and session keys are derived immediately from these ephemeral keys rather than from long-term stored keys. This preliminary use of ephemeral material ensures that even if the drone is captured later, the session keys remain protected.
Solution Approach 2:
The protocol changes the parameter basis for key derivation from static long-term keys to dynamic ephemeral keys for each session. This parameter change ensures that compromise of the drone's stored long-term keys does not affect the security of past session keys derived from different ephemeral parameters.
4Productivity
If simultaneous key exchange with multiple users is required, then communication efficiency can be improved, but existing protocols require continuous server communication which increases complexity
Solution Approach 1:
The protocol enables terminals to perform self-service key exchange by establishing ephemeral key pairs and deriving session keys locally without requiring continuous server intervention. The server is only needed for initial registration, after which terminals can independently conduct multiple simultaneous key exchange sessions.
Solution Approach 2:
Terminals perform preliminary key pair generation and store their public keys locally, enabling them to initiate and complete key exchange sessions independently. This preliminary setup allows simultaneous sessions with multiple users without requiring the server to be involved in each individual key exchange.
Data Source
AI summary
Provided is a session key exchange method of a first terminal, the session key exchange method including determining a first pseudonym identifier (PID), of the first terminal, to be used in a communication session with a second terminal, transferring the first PID to the second terminal, transferring a first cipher text and a first message authentication code (MAC) value identified based on a second PID identified from the second terminal and the first PID to the second terminal, and identifying a session key to be used in the communication session with the second terminal based on the second PID, a second cipher text, a second MAC value, which are identified from the second terminal, and the first PID.