Description
The Personalisation Control Key (PCK) is a security feature defined within the 3GPP UICC (Universal Integrated Circuit Card) and USIM (Universal Subscriber Identity Module) application toolkit. It is a secret cryptographic key, typically 128 bits long, stored securely in a protected file (EF_PCK) on the UICC. The primary function of the PCK is to facilitate network, service provider, or corporate personalisation of the Mobile Equipment (ME). Personalisation refers to the ability to restrict the ME's operation to work only with a specific UICC, network, or set of services. The mechanism is invoked via the "PERSONALISE" command from the UICC to the ME, which includes a challenge-response authentication protocol using the PCK.
The technical process works as follows: When a personalised ME is powered on with a UICC, the ME reads the personalisation data from the UICC. If personalisation is active, the ME sends a random challenge (RAND) to the UICC. The UICC uses the stored PCK and a cryptographic algorithm (like MILENAGE) to compute a response (RES) and an expected response (XRES). The RES is sent back to the ME. The ME, which also possesses the PCK (programmed into its non-volatile memory during the personalisation process), independently computes the XRES using the same RAND and algorithm. If RES matches XRES, the personalisation check passes, and the ME operates normally. If the check fails, the ME may deny service, restrict functionality, or display a message, depending on the personalisation category (e.g., network, service provider, corporate).
The architecture involves several components: the ME's personalisation framework, the UICC's USIM application with the PCK file, and the over-the-air (OTA) platform used to provision or update the PCK on the UICC. The PCK is distinct from the authentication keys (Ki/K) used for network access; it is solely for device locking. Its role is critical for enforcing commercial policies. For example, a subsidised phone sold by Operator A is personalised with Operator A's PCK, preventing its use with a competitor's SIM until unlocked. The specifications detail multiple personalisation categories (Network, Network Subset, Service Provider, Corporate) each potentially with its own PCK, allowing for granular control. Management commands allow for disabling personalisation (unlocking) if the correct PCK is provided.
Purpose & Motivation
The PCK was introduced to address the commercial need for network operators and handset manufacturers to control the usage environment of mobile devices, particularly in markets where handsets are heavily subsidised. Without such a mechanism, a subsidised device could be immediately used with a competitor's SIM card, undermining the business model of recouping subsidy costs through service revenue. Prior to standardised personalisation, proprietary locking solutions existed, leading to fragmentation and interoperability issues. The PCK, standardised from Release 4 onwards, provided a universal, secure method for personalisation across all 3GPP-compliant devices and UICCs. It solves the problem of device locking in a cryptographically secure manner, preventing easy circumvention. Its creation was motivated by the desire to protect operator investments, manage device fleets for corporate customers, and enable branded service offerings, while maintaining a standardised security framework that is interoperable between different ME and UICC vendors.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (41 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-4, normative work from Rel-15.
In Release 15, the PCK (Personalisation Control Key) function was not newly introduced or modified; the provided Change Request titles and grounding context exclusively detail updates to Multi-Talker floor control procedures, including enhancements to the Floor Control Server, support for functional aliases in floor control messages, and updates to state transition diagrams for general floor control operation.
- Multi-Talker floor control server TS 24.380CR0178
- Mutli-talker – floor control towards the participant TS 24.380CR0179
- Updates to Non-controlling MCPTT function for Multi Talker TS 24.380CR0183
- Floor Control Server towards participant TS 24.380CR0187
- Coding of floor control messages to support functional alias TS 24.380CR0192
- Procedures for floor control messages to support functional alias TS 24.380CR0193
+ 2 more changes
In Release 16, the new PCK (Personalisation Control Key) function was specifically established for MCData, enabling corporate personalisation control for mission-critical data services. This introduction provided a defined mechanism for personalising equipment to restrict its use with specific corporate USIMs, extending security and management capabilities within the 3GPP system. The establishment procedures were detailed to allow verification checks and control over the personalisation state.
- Media plane control in MCData for user plane SDS using MBMS TS 24.582CR0011
- [33.180] R16 Establishment of PCK for MCData TS 33.180CR0112
- Incorrect reference to table for MBMS Subchannel Control TS 24.581CR0038
- Minor corrections in transmission control state machine TS 24.581CR0066
- New instance creation and release for basic / general reception control state m/c. TS 24.581CR0073
- Corrections to Off-Network Floor Control procedures TS 24.380CR0235
+ 6 more changes
In Release 17, the enhancements to the Personalisation Control Key (PCK) function were not detailed in the provided grounding context or within the listed Change Request titles. The CR titles primarily address corrections and updates to mission-critical services like floor control, call setup, and media plane procedures for MCPTT, MCData, and MCVideo. Therefore, based solely on the given materials, no specific new features or changes for the PCK function in Release 17 can be described.
- MCVideo Functional Alias usage in Transmission Control TS 24.581CR0079
- MCData media plane control for FD using MBMS delivery via MB2 TS 24.582CR0025
- Corrections to floor indicator of On-Network Floor Control procedures TS 24.380CR0274
- Corrections to floor control messages handling for upgrade/downgrade of broadcast call TS 24.380CR0289
- Updates to clause 6.3.5 Floor control server state transition diagram for basic floor control operation towards the floor participant and related editorials TS 24.380CR0298
- Corrections in call setup control over pre-established session state machine TS 24.380CR0307
+ 4 more changes
In Release 18, the enhancements for the Personalisation Control Key (PCK) function are not detailed within the provided grounding context or the listed Change Request titles. The given CRs focus on Mission Critical services like MCPTT and MCVideo, covering areas such as multiplexing support, timer additions for MBS channel control, and corrections to transmission control messages, but they do not specify any new features or modifications related to PCK personalisation, de-personalisation, or corporate personalisation controls.
- Add timers and counters in the participating MCPTT function for MBS channel control TS 24.380CR0347
- MCPTT support of multiplexing - SSRCs used for RTP audio and RTCP floor control TS 24.380CR0356
- Add timers and counters in the participating MCVideo function for MBS channel control TS 24.581CR0111
- MCVideo support of multiplexing - SSRCs used for RTP media and RTCP transmission control TS 24.581CR0117
- Addition of Reason cause value in Pre-Established Session Call Control Disconnect Message to indicate media bearer failure TS 24.380CR0349
- Corrections to acknowledgment required bit of transmission control ack message TS 24.581CR0090
+ 2 more changes
In Release 19, the PCK (Personalisation Control Key) function was enhanced with miscellaneous corrections to its floor control procedures, ensuring more reliable operation. The release also introduced an upgrade to the change control version for this function, improving its management and versioning framework. These updates built upon the existing personalisation and de-personalisation processes for controlling ME and (U)SIM interoperability.
Explore further
Broader topics and technologies where PCK plays a role.
Defining Specifications
3GPP specifications that define or reference PCK, 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 22.022 vj00 | ME Personalisation Features for GSM/3G | Rel-19 |
| TS 24.380 vj10 | MCPTT Media Plane Control Protocol | Rel-19 |
| TS 24.581 vj00 | MCVideo Media Plane Control Protocol Specification | Rel-19 |
| TS 24.582 vj00 | MCData Media Plane Control Protocols | Rel-19 |
| TS 29.380 vj00 | MCPTT-LMR Interworking Media Plane Control | Rel-19 |
| TS 29.582 vj00 | MCData Interworking with LMR Systems | Rel-19 |
| TS 33.179 vdc0 | MCPTT Security Architecture and Procedures | Rel-13 |
| TS 33.180 vk00 | Security of Mission Critical (MC) Service | Rel-20 |
| TS 33.879 vd10 | MCPTT Security Study | Rel-13 |
| TS 33.880 vf10 | Security Study for Enhanced Mission Critical Services | Rel-15 |
| TR 33.938 vj10 | 3GPP Cryptographic Inventory for 5G | Rel-19 |