Table 4 Two-level privacy protection strategy in enhanced EAADE.

Pseudonym rotation

Prevent long-term identity tracking and linkage attacks

\(\bullet\) Generate fresh random \(r_i' \in \mathbb {Z}_q^*\)

\(\bullet\) Compute new pseudonym: \(PUname_i' = h(Uname_i \Vert r_i' \cdot \textbf{G})\)

\(\bullet\) Obfuscate: \(APUname_i = PUname_i' \oplus h(d_i \cdot Pu)\)

\(\bullet\) Old and new pseudonyms are unlinkable

Spatial cloaking

Protect geographical location and trajectory tracking

\(\bullet\) Define cloaking zone \(CloakZone_i\)

\(\bullet\) Ensure \(|\text {Vehicles in zone}| \ge k\) (k-anonymity)

\(\bullet\) Dynamic radius \(r_i\) adjusted according to density

\(\bullet\) Transmit only zone index, not \((x_i, y_i)\)

Integration in authentication

Embed privacy into secure message flow

\(\bullet\) Send \((APUname_i, CloakZone_i)\) in \(W_1\)

\(\bullet\) RSU verifies cloaking & pseudonym validity via VCList

\(\bullet\) Ensures unlinkability across sessions