Description
File Control Parameters are a critical component of the UICC (Universal Integrated Circuit Card) and USIM (Universal Subscriber Identity Module) architecture, defined within the framework of the USIM Application Toolkit (USAT). They are metadata associated with every file (both Elementary Files, EFs, and Dedicated Files, DFs) residing on the UICC's file system. These parameters are stored within the file's header or a dedicated administrative file and are read by the terminal (mobile equipment) to understand how to interact with a specific file correctly and securely. The parameters define the file's fundamental characteristics and the rules for accessing its content.
The structure and encoding of FCP are standardized, primarily in 3GPP TS 31.102, which details the USIM characteristics. When a terminal selects a file on the UICC, it receives the File Control Parameters in a response. These parameters include the file size (indicating the number of bytes), the file identifier (a unique 2-byte address), the file's lifecycle status (e.g., created, initialized, operational, terminated), and crucially, the security attributes. The security attributes define the access conditions for various operations like reading, updating, increasing, or invalidating the file. These conditions can be 'always', 'never', or require a specific security context such as successful PIN (CHV) verification, administrative keys (ADM), or never allowing access.
Furthermore, FCP can specify the file's structure, such as whether it is a linear fixed, linear variable, cyclic, or transparent file. For structured files, additional parameters like record length or the number of records are included. The role of FCP is foundational; they act as the rulebook that governs all file system interactions on the smart card. Without correctly interpreting FCP, a terminal could not read subscriber identity (IMSI), network authentication keys (Ki), phonebook entries, or SMS storage. They enforce the security model, preventing unauthorized access to sensitive data and ensuring the integrity of the UICC's file system, which is a trusted environment in the mobile network ecosystem.
Purpose & Motivation
The purpose of File Control Parameters is to provide a standardized, secure, and flexible mechanism for managing the hierarchical file system on a UICC smart card. Before such standardization, proprietary methods for file management led to interoperability issues between different card manufacturers and mobile equipment. The FCP framework solves this by defining a universal set of metadata that any compliant terminal can interpret, enabling seamless interaction with USIMs from any vendor.
Their creation was motivated by the need for a robust security and access control model on the subscriber identity module. The SIM/USIM card stores highly sensitive information, including the subscriber's unique identity (IMSI), long-term authentication key (Ki), and personal data. FCP enforces mandatory access control, ensuring that critical files cannot be read or modified without the proper authentication (e.g., PIN verification). This protects the subscriber from identity theft and the network from fraudulent access. Furthermore, as the USIM evolved from a simple authentication token to a platform for multiple applications (USAT), the FCP system provided the necessary structure to manage a complex, multi-application file system with varying security requirements for different files and applications.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (37 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-6, normative work from Rel-15.
In Release 15, the FCP (File Control Parameters) function was updated to enhance USIM management procedures for 5GS, specifically by decoupling the routing ID storage from other SUCI calculation parameters. Furthermore, control plane-based Steering of Roaming (SoR) functionality was streamlined by removing a dedicated elementary file and consolidating its use within the EF-UST (USIM Service Table). Updates also included extending USIM OPL configuration to support a 3-byte TAC for operation in NG-RAN.
- USIM Service Table update for PDU session call control support TS 31.102CR0786
- Allow configuration of MCS (Access Identity 2) via USIM. TS 31.102CR0794
- Mission Critical Services configuration data update to USIM TS 31.102CR0808
- Remove the control plane based SoR related EF and use only the EF-UST. TS 31.102CR0798
- Corrections to the control plane based SoR related EF TS 31.102CR0799
- Enhance USIM OPL configuration to support 3 bytes TAC when in NG-RAN. TS 31.102CR0818
+ 3 more changes
In Release 16, the File Control Parameters (FCP) function was enhanced primarily through new USIM configuration capabilities. These included the storage of a URSP (UE Route Selection Policy) list, a list for Trusted non-3GPP access networks, and a PS Data Off list for home and roaming. The release also introduced support for configuring RLOS (Restricted Local Operator Services) PLMN and MCC lists, and clarified procedures for reading the UAC Access Identities Configuration EF.
- Support for USIM configuration of RLOS PLMN list TS 31.102CR0847
- URSP storage in USIM TS 31.102CR0861
- Specify storage for a potentially separate KSEAF for non-3gpp access on the USIM TS 31.102CR0864
- USIM configuration of RLOS allowed MCC list TS 31.102CR0881
- Support for Trusted non-3GPP access networks list by USIM TS 31.102CR0891
- Dedicated AID for USIM Applications with non-IMSI based SUPI Types TS 31.102CR0897
+ 3 more changes
In Release 17, the FCP function was enhanced through several new USIM files for storing network configuration parameters. These additions included dedicated files for pre-configured CAG information, SOR-CMCI parameters, disaster roaming settings, eDRX parameters for NG-RAN, and configurations for 5G NSWO and warning messages in SNPNs. The release also introduced support for 'No E-UTRA Disabling In 5GS' and included corrections to existing parameters like SM_RetryWaitTime in the EF NASCONFIG file.
- Introduce a USIM file to store pre-configured CAG information list TS 31.102CR0904
- SOR-CMCI storage in USIM TS 31.102CR0917
- Addition of USIM files for the indication of whether disaster roaming is enabled in the UE, disaster roaming wait range, disaster return wait range and applicability indicator for disaster roaming PLMNs list provided by VPLMN. TS 31.102CR0938
- Adding eDRX parameters in the USIM for NG-RAN TS 31.102CR0943
- 5G NSWO (Non-Seamless WLAN Offload) configuration support in the USIM compromised proposal. TS 31.102CR0946
- Support of 'No E-UTRA Disabling In 5GS' in USIM TS 31.102CR0947
+ 3 more changes
In Release 18, the File Control Parameters (FCP) function was extended to include new Elementary Files (EFs) on the USIM for storing parameters related to SENSE, IMS Data Channel configuration, and Access Control to GBA_U_APIs. It also introduced updates for UE pre-configuration of 5MBS parameters and added a pre-configured list of PLMNs for MINT in the Disaster Roaming Information EF. Furthermore, this release mandated that Service n°133 be enabled when Service n°123 is enabled for extended 5G security parameter storage and fixed issues with File Identifiers for Access Control files.
- Addition of EF to store parameters for SENSE TS 31.102CR0978
- 5G Security Parameters extended storage on USIM (Mandating Service n°133 to be enabled when Service n°123 is enabled) Rel18. TS 31.102CR1014
- Add EF of Access Control to GBA_U_APIs to the USIM TS 31.102CR1007
- Add EF of IMS Data Channel configuration to the USIM TS 31.102CR1006
- Update to UE pre-configuration for 5MBS parameters TS 31.102CR0996
- Fix issues with FID for Access Control files TS 31.102CR1041
+ 1 more changes
In Release 19, the FCP (File Control Parameters) function was updated to introduce new operator-controlled parameters for PLMN selection, specifically the "Operator-controlled-LSP-PLMN" and the "PeriodicSearchTimerNonLSP." The release also included a correction to EFNASCONFIG parameters and defined backward compatibility handling for USIMs lacking extended security parameter storage in the EF_5GAuthKeys file.
Explore further
Broader topics and technologies where FCP plays a role.
Defining Specifications
3GPP specifications that define or reference FCP, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TS 31.102 vj40 | USIM Application Specification | Rel-19 |