SUCI (Subscription Concealed Identifier)

The Subscription Concealed Identifier is the encrypted form of the SUPI used in 5G to prevent passive over-the-air tracking. The UE generates a fresh SUCI for each transmission by encrypting the SUPI with the home network's public key (using ECIES), so a passive observer or rogue base station cannot derive the long-term subscriber identity. The home network's UDM/SIDF decrypts the SUCI back to the SUPI for authentication, closing one of the most exploited weaknesses of 2G/3G/4G.

Categories: Radio Access NetworkCore NetworkRoaming and Interconnect

SUCI in context

The radio access network is where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations and downgrade attacks; defenses rest on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

The mobile core carries subscriber sessions, mobility and policy. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF.

To place SUCI in the wider telecom-security picture, review AUSF, Grey Routing, Red Team, Threat Intelligence, 5G and 5G SA — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.