What is SUCI (subscription concealed identifier)

SUCI (Subscription Concealed Identifier) Explained Technically

In the context of 5G mobile networks, SUCI (Subscription Concealed Identifier) plays a crucial role in enhancing subscriber privacy. Here's a breakdown of the key technical details:

Protecting User Identity:

• Challenge in Traditional Mobile Networks: In previous generations of mobile networks (e.g., 4G LTE), the International Mobile Subscriber Identity (IMSI) served as a unique identifier for a subscriber. However, transmitting IMSI in plain text poses privacy concerns as it can be linked to a specific user.
• SUCI to the Rescue: SUCI addresses this privacy concern by providing a concealed identifier for the subscriber. It essentially hides the IMSI while still allowing the network to identify and authenticate the subscriber during registration and service access.

SUCI Generation and Usage:

• MME (Mobility Management Entity): The Mobility Management Entity (MME) in the 5G core network plays a central role in SUCI generation and usage.
• Registration Process: During the registration process, the User Equipment (UE) transmits its IMSI along with other information to the MME.
• Encryption and Derivation: The MME utilizes the IMSI and a secret key (known only to the network) to perform an encryption operation. This generates the SUCI, which is a concealed version of the IMSI.
• Network Communication: The UE transmits the SUCI instead of the IMSI during subsequent communication with the network for tasks like authentication, authorization, and service access.
• Decon concealment (Optional): If required for specific network functions, the MME can decrypt the SUCI back to the original IMSI using the same secret key.

Benefits of SUCI:

• Enhanced Subscriber Privacy: By using SUCI, the network can identify and manage subscribers without exposing their actual IMSI in cleartext. This reduces the risk of user identity tracking and potential misuse.
• Compliance with Regulations: SUCI helps mobile network operators comply with evolving privacy regulations that mandate stronger protection of subscriber identities.
• Improved Security: Concealing the IMSI adds an extra layer of security to the communication between the UE and the network, making it more difficult for unauthorized parties to intercept and exploit subscriber information.

Additional Considerations:

• SUCI Profile Configuration: The network operator configures the SUCI profile within the MME, which specifies the encryption scheme and other parameters used for SUCI generation and processing.
• Support for Legacy Systems: While SUCI is a key feature in 5G, some network functions might still require the IMSI. Mechanisms exist to securely exchange the IMSI when necessary.

Understanding SUCI is valuable for engineers working on:

• 5G network design, development, and deployment.
• Security and privacy aspects of mobile communication systems.
• Development of privacy-preserving protocols for mobile networks.

SUCI represents a significant advancement in protecting subscriber privacy within 5G mobile networks. By concealing the IMSI, it allows for secure and anonymous communication while still enabling necessary network functionalities. As privacy concerns continue to grow, SUCI is expected to play a vital role in ensuring a secure and privacy-conscious mobile experience for users.