5G SUCI-catchers

Abstract

In mobile networks, IMSI-Catchers identify and track users simply by requesting all users' permanent identities (IMSI) in range. The 5G standard attempts to fix this issue by encrypting the permanent identifier (now SUPI) and transmitting the SUCI. Since the encrypted SUCI is re-generated with an ephemeral key for each use, an attacker can no longer derive the user's identity. However, this scheme does not prevent all tracking and linking: if the identity of a user is already known, an attacker can probe users for that identity.