Secure registration for a multicast-broadcast-multimedia system (MBMS)

The present invention generally relates to telecommunications, and in particular to security in communication systems.

In wireless communication systems that carry non-voice traffic such as video, data, multimedia, or other types of traffic in addition to voice traffic, a typical cellular base station requests service within the coverage area of the base station. If the number of users exceeds a predetermined threshold, the multimedia traffic service can be broadcast. The multimedia traffic service may be a video stream, for example a sporting event or a mountainous portion of a sporting event. If there are not enough users requesting service in the coverage area, the base station will request the service through a dedicated channel instead of broadcasting the service to all users in the coverage area. The service can be sent only to the user.

Occasionally, a rogue or illegal user broadcasts a service to all users in the coverage area by registering multiple times in idle mode, for example by pretending to be a number of different identities. You may try to force the base station to do so. When one or more illegal users use their mobile phone in idle mode to register multiple times in the coverage area to receive the content of an event, the base station registers the number of registrations as a legitimate user registration for the event. The event may be broadcast to all users in the coverage area.

Therefore, network operators and content providers have a reliable means of ensuring that only legitimate registrations for multimedia events are counted in the coverage area, and fake registrations for all users in the coverage area. There is a need in the art to not be compelled to broadcast.

[wrap up]

The embodiments disclosed herein are described above by methods and devices for obtaining secure registration in a multicast broadcast multimedia system (MBMS) using a temporary registration key (RGK). Meet your needs.

[Detailed description]

The term "exemplary" is used herein to mean "example, case, or exemplary." Any embodiment described herein as "exemplary" should not necessarily be construed as preferred or advantageous as compared to other embodiments. All embodiments described in this detailed description are provided to allow one of ordinary skill in the art to manufacture or use the present application, and the scope of the invention as defined by the claims. It is an exemplary embodiment that is not provided for limitation.

Mobile stations, also referred to as user equipment (UE), can communicate with one or more base stations. The mobile station transmits and receives data packets to and from the base station controller via one or more base stations. A base station and a base station controller are parts of a network called an access network. The access network carries data packets between multiple mobile stations. The access network may also be connected to an additional network outside the access network, such as a corporate intranet or the Internet, and may carry data packets between each mobile station and such an external network. A mobile station that has established an active traffic channel connection with one or more base stations is called an active mobile station and is said to be in a traffic state. A mobile station in the process of establishing an active traffic channel connection with one or more base stations is said to be in a connection setup state. A mobile station that is powered on and capable of receiving signals from a base station but not in a traffic state or connection setup state is said to be in an idle state.

A communication link in which a mobile station transmits a signal to a base station is called a reverse link. A communication link in which a base station transmits a signal to a mobile station is called a forward link. A mobile station or user equipment (UE) is a mobile phone handset, also known as a mobile equipment (ME), and a smart card or UICC that is removable or permanently attached to the ME. It may be a mobile phone that includes a memory module, such as a physically secure IC card. In the Global System for Mobile communication (GSM) telephone, the UICC is usually the subscriber identity module (SIM). For Code Division Multiple Access (CDMA) phones, the UICC is usually a removable user identity module (RUIM).

Figure 1 illustrates a communication link between user equipment (UE) 2, in service (serving) network 4, home network 6 and content provider (CP) 8 in a multicast broadcast multimedia system (MBMS). It is an exemplary block diagram. The user device 2 may be a mobile station including a portable device (ME) 10 and a memory module or UICC 12. The UICC 12 may be a removable memory module attached to the mobile device 10 or a permanent portion of the mobile device 10. The physical implementation of UICC 12 on user device 2 is not important to the present invention.

Even if the network 4 in service is owned by a wireless carrier that provides a subscription service to the user device 2, the service is provided to the user device 2 while the user device 2 is roaming. It may be a visited network owned by another carrier. The serviced network 4 typically includes a radio access network (RAN) 14 and a general line radio service (GPRS) support node (SGSN) 16 in service. A radio access network 14, also known as a base station (BS), base transceiver station (BTS), or access point (AP), transmits radio signals to user equipment 2 and receives radio signals from user equipment 2. SGSN16 is a core network node that can be, for example, part of a public land mobile network (PLMN).

The home network 6 is a network owned by a wireless carrier that provides a subscription service to the user device 2, and the network 4 in service depends on whether or not the user device 2 is roaming outside the service area of the carrier. It may or may not be owned by the same carrier as the one. Home network 6 typically includes gateway GPRS support node (GGSN) 18, broadcast multicast service center (BM-SC) 20 and home subscriber server (HSS) 22. The solid line 22 in FIG. 1 represents a bearer path in which a signal with information is carried from the content provider 8 to the mobile device 10 via the home network 6 and the in-service network 4. The dotted line 24 in FIG. 1 represents the key / authentication path in which the encryption and decryption keys are passed between UICC 12, network 4 in service, and home network 6.

Content provider 8 may be a third-party content source that is not owned by either the home network carrier or the network carrier in service. The home subscriber server 22 of the home network 6 holds the subscription status of the mobile phone and bills the multicast service billing data (billing). It may include a database for collecting data). In the embodiment shown in FIG. 1, the home network 6 also includes a broadcast multicast service center (BM-SC) 20 that schedules multimedia events and performs at least some security function against the MBMS. .. If network 4 in service sends the content to a single user through a dedicated channel and the number of users requesting the service does not justify broadcasting the service to all users in the coverage area, the content Is a network that broadcasts content to all users in the coverage area when the number of users requesting services exceeds a predetermined threshold or multicasts to a plurality of users via a dedicated channel.

In one embodiment, the content of a multimedia event is encrypted and decrypted at several levels in order to provide at least some guarantee that an unauthorized user will not be able to view the multimedia event by decrypting the data. It is encrypted and decrypted by a multicast broadcast multimedia system through. For example, a permanent, user-specific registration key (RK) may be provided to generate a temporary key (TK) value and authenticate the UICC of the user's mobile phone. The TK is a disposable, user-specific key used to encrypt the value of the broadcast access key (BAK). TK is also used by UICC to decode BAK values. A BAK is a medium-term, shared key that is used to obtain multiple short-term keys (SKs) and is distributed to each user's UICC. SK is a frequently changing, shared key used to encrypt and decrypt content. SK is explicitly (in the) with encrypted content and BAK clear) It may be generated using a random number (SK_RAND) to be transmitted. UICC12 regenerates SK from BAK and SK_RAND and passes SK to mobile device 10. An example of the data content encryption and decryption scheme (schemes) in a multicast broadcast multimedia system was filed on August 20, 2001, "Methods and Devices for Security in Data Processing Systems (" It is described in US Patent Application No. 09 / 933,972 entitled "Method and MFP for Security in a Data Processing System" and is incorporated herein by reference. Various other embodiments using public or shared private keys for encryption and decryption can also be implemented within the scope of the invention. For example, in another embodiment, secure delivery or delivery of BAK to UICC may be provided using public key mechanisms such as RSA and ElGamal, which are known to those of skill in the art.

Figure 2 shows secure registration in a multicast broadcast multimedia system. An embodiment of registration) will be described. In this embodiment, the Broadcast Multicast Service Center (BM-SC) 20 sends a provisioning message, which is referred to as the Public Ground Mobile Network (PLMN) key called PK and RK. It is a function with an immutable, user-specific registration key. PK is a temporary, home PLMN-specific key used to generate a radio access network (RAN) key called RAK and authenticate UICC12. The provisioning message is sent from the BM-SC20 to the UICC 12 along path 26, as described in Figure 2. The provisioning message, which is a function with arguments PK and RK, can be represented as c1 (PK, RK). Upon receiving the provisioning message, UICC12 extracts the PK from the provisioning message and stores the PK value. Other embodiments for achieving secure delivery or supply of PK to UICC may be provided within the scope of the invention using public key mechanisms, including but not limited to RSA and ElGamal.

The radio access network (RAN) 14 sends RAK and random number (RAND) requests to the BM-SC20 along path 28, which in response is a function RAK with arguments PK and RAND. To generate. RAK, which can be represented as c2 (PK, RAND), is transmitted by BM-SC20 to RAN14 along path 30. A RAK is a temporary, RAN-specific key used to generate a temporary, user-specific registration key (RGK) value and hide the PK from RAN14 accessed by UE2. RAK is also a user identification number, such as a P-TMSI, IMSI, electronic serial number (ESN), MIN, or any immutable or temporary user identification number used in a system in which embodiments of the present invention are realized. It is also used to encrypt the MBMS service identification number (Serv_ID). In the embodiments shown in FIGS. 2 and 3, P-TMSI is used as an exemplary user identification number known to those of skill in the art.

The RAN may store the RAK and broadcast the RAND to all users including UE2 in the coverage area of the RAN along the path 32. When UE2 receives the RAND, it sends the RAND to UICC12 along path 34 as well as the P-TMSI and Serv_ID. UICC12 produces a RAK that is an exact copy of the RAK produced by the BM-SC20. After receiving the Serv_ID and P-TMSI, UICC12 concatenates the Serv_ID and P-TMSI to obtain the concatenated result shown as [Serv_ID || P-TMSI], based on the Serv_ID and P-TMSI. Calculate the Cyclic Redundancy Check (CRC). The CRC is attached to [Serv_ID || P-TMSI] to generate [Serv_ID || P-TMSI || CRC]. UICC12 then generates RGK, which is a function of Serv_ID, P-TMSI, CRC, and RAK, represented as c3 ([Serv_ID || P-TMSI || CRC], RAK). The RGK is a temporary, user-specific key used to authenticate registration messages.

After the RGK is generated, UICC12 sends the RGK to UE2 along path 36, which in turn sends a registration / connection request containing the RGK to RAN14 along path 38. Upon receiving the registration / connection request, RAN14 extracts [Serv_ID || P-TMSI], checks the CRC, and sends a valid registration message requesting multimedia services to the user identified by P-TMSI. Count as a legitimate user. If the registration / connection message sent by the user is not verified by RAN14, RAN considers the user an illegal or illegal user and does not justify the request.

FIG. 3 illustrates another embodiment of secure registration in a multicast broadcast multimedia system. In this embodiment, the Broadcast Multicast Service Center (BM-SC) 20 does not send provisioning messages. Instead, the radio access network (RAN) 14 sends a RAK and random number (RAND) request to the BM-SC20 along path 40, which in response generates a RAK and RAND. .. RAK is a function with arguments BAK and RAND, represented as c2 (BAK, RAND) . BAK is the same broadcast access key used as part of the encryption mechanism that encrypts the data content described above. RAND and RAK are transmitted by BM-SC20 to RAN14 along path 42. A RAK is a temporary, RAN-specific key used to generate a temporary, user-specific registration key (RGK) value. RAK is also used to encrypt the MBMS Service Identification Number (Serv_ID) and the User Identification Number called P-TMSI.

The RAN stores the RAK and broadcasts the RAND to all users including UE2 in the coverage area of the RAN along the path 44. When UE2 receives the RAND, it sends the RAND to UICC12 along path 46 as well as the P-TMSI and Serv_ID. UICC12 produces a RAK that is an exact copy of the RAK generated by the BM-SC20. After receiving the Serv_ID and P-TMSI, UICC12 concatenates the Serv_ID and P-TMSI to obtain the concatenated result, shown [Serv_ID || P-TMSI], and patrolls based on the Serv_ID and P-TMSI. Calculate the redundant code (CRC). The CRC is added to [Serv_ID || P-TMSI] to generate [Serv_ID || P-TMSI || CRC]. UICC12 then generates RGK, which is a function of Serv_ID, P-TMSI, CRC, and RAK, represented as c3 ([Serv_ID || P-TMSI || CRC], RAK). The RGK is a temporary, user-specific key used to authenticate registration messages.

After the RGK is generated, UICC12 sends the RGK to UE2 along path 48, which in turn sends a registration / connection request containing the RGK to RAN14 along path 50. Upon receiving the registration / connection request, RAN14 extracts [Serv_ID || P-TMSI], checks the CRC, and sends a valid registration message requesting multimedia services to the user identified by P-TMSI. Count as a legitimate user. If the registration / connection message sent by the user is not confirmed by RAN14, RAN may consider the user an illegal or illegal user and does not justify the request.

The RAN14 receives multiple registration / connection requests from multiple users in the coverage area and calculates from each user's Serv_ID and P-TMSI which request is valid and sent by a legitimate user. It can be judged by checking the CRC. The RAN may ignore requests with an RGK containing an unverifiable CRC. In this way, the RAN has a reliable means of determining how many registration requests are valid for a multimedia event, and justifies a number of legitimate users to broadcast the event. If it is not enough to make the event broadcast, it will not be forced to broadcast the event.

Various other features may also be added to the Temporary Registration Message (RGK) within the scope of the present invention. For example, a time stamp for system time may be added to the RGK. If the RAN has P-TMSI for all subscribers in the coverage area, RAN14 will use the P-TMSI extracted from RGK to determine if the user trying to register is really a subscriber. You may. In a typical GSM system, P-TMSI may be assigned at the GSM / GPRS logical link control (LLC) level, ie at the core network (CN). In another embodiment, replay by an illegal user The public key may be used when forming the RGK to avoid attacks). For example, if each UICC has a private key used to supply the PK or BAK, the RGK may include a public key reference or certificate, and a BAK or PK hash signature. Replay attacks by illegal users can be avoided or at least restricted by using techniques such as digital signatures or sequence numbers based on public key cryptography.

The order of the body of any claim means that the processing steps must be performed in a temporal or logical order according to such order, unless otherwise defined by the wording of the claim. It's not a thing. The processing steps can be replaced in any order without departing from the scope of the invention, as long as such replacement is consistent with the wording of the claims and is not logically meaningless. Furthermore, ordinal numbers such as "first," "second," and "third" simply mean different individuals of a plurality of things, meaning any order or sequence, unless otherwise defined by the wording of the claim. do not do.

In addition, the words "connect", "connect to" and "connect" used to describe relationships between different elements must make a direct physical connection between these elements. Does not mean. For example, two elements may be physically, electrically, logically, or otherwise connected to each other through one or more additional elements without departing from the scope of the invention. ..

Those skilled in the art will appreciate that information and signals can be represented using any of a variety of different techniques and techniques. For example, the data, instructions, commands, information, signals, bits, symbols, and chips referred to throughout the above description may be voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or particles, or these. It may be represented by any combination.

Those skilled in the art will further appreciate the various logical blocks, modules, circuits, and examples of algorithmic steps described in connection with the embodiments disclosed herein in electronic hardware, computer software, or a combination thereof. You will recognize that it can be realized as. To articulate this compatibility of hardware and software, examples of various components, blocks, modules, circuits, and steps are generally described above with respect to their functionality. Whether such functionality is realized as hardware or software depends on the design constraints imposed on the entire system and the specific application. The skilled worker may achieve the described functionality in various ways for a particular application, but the determination of such realization should not be construed as causing a deviation from the scope of the invention.

Examples of various logic blocks, modules, and circuits described in connection with the embodiments disclosed herein include general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), and field programmables. Implemented or implemented by a gate array (FPGA) or programmable logic device, discrete gate or transistor logic, separate hardware components, or any combination of these designed to perform the functions described herein. You may. The general purpose processor may be a microprocessor, but in another option, the processor may be any conventional processor, controller, microcontroller, or state machine. Processors are also implemented as a combination of computing devices, such as a combination of DSP and microprocessor, multiple microprocessors, one or more microprocessors in conjunction with the DSP core, or any other such configuration. May be done.

The steps of methods or algorithms described in connection with the embodiments disclosed herein may be embodied directly in hardware, in software modules executed by a processor, or in combination of the two. Software modules include random access memory (RAM), flash memory, read-only memory (ROM), erasable PROM (EPROM), electrically erasable / programmable ROM (EEPROM), registers, hard disks, removable disks, and CD ROMs. -ROM), or may reside in any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from and write information to the storage medium. Alternatively, the storage medium may be integral with the processor. The processor and storage medium may reside, for example, as separate components in a base station or in a single ASIC.

The above description of the disclosed embodiments is provided so that any person skilled in the art can manufacture or use the present invention. Various variations on these embodiments will be readily apparent to those of skill in the art, and the general principles defined herein are other embodiments without departing from the spirit or scope of the invention. Applicable to morphology. Accordingly, the present invention is not intended to be limited to the embodiments presented herein, but should be consistent with the broadest scope consistent with the principles and novel features disclosed herein. is there.

<figref num="1">FIG. 1 is an exemplary block diagram illustrating a multicast broadcast multimedia system (MBMS) communication link.</figref><figref num="2">FIG. 2 is a diagram illustrating an embodiment of secure registration in MBMS.</figref><figref num="3">FIG. 3 illustrates another embodiment of secure registration in MBMS.</figref>