Method for preventing mapping of user identifiers in mobile communication system and the system thereof

Abstract

The present invention relates to a method and system for preventing user identifier mapping in a mobile communication system, which blocks the capture of traffic volume by an attacker by preventing an attacker from associating an observed RNTI (Radio Network Temporary Identifier) ​​with the TMSI (Temporary Mobile Subscriber Identity) of a target device. The method comprises the steps of: receiving an encrypted RRC Connection Reconfiguration message from a base station when establishing a wireless connection at a target device; receiving a new RNTI (Radio Network Temporary Identifier) ​​issued by the base station in response to the RRC Connection Reconfiguration message at the target device; and using the new RNTI at the target device.

Description

Technology Field

[0001] The present invention relates to a method and system for preventing user identifier mapping in a mobile communication system, and more specifically, to a method and system for blocking the capture of traffic volume by an attacker by preventing an attacker from associating an observed RNTI (Radio Network Temporary Identifier) ​​with the TMSI (Temporary Mobile Subscriber Identity) of a target device. Background Technology

[0002] Mobile communication networks are the dominant means of delivering video streams. An increasing number of users are utilizing mobile networks to watch video streaming services on mobile devices. Video streaming services such as YouTube and Netflix are further accelerating this trend by enriching the user experience with diverse video content. Due to this trend, an individual's video viewing history reveals increasingly more information. While people are reluctant to share personal information, their history can reveal their political, financial, and personal preferences. Therefore, the ability to identify the videos an individual has watched represents a serious privacy threat, and the most common protection against this threat is to transmit video data traffic encrypted via HTTP.

[0003] However, according to recent research, there exist video identification attacks that can identify video through the analysis of encrypted traffic. The video identification attack presented in LTE networks exploits the fact that (1) each video stream generates a distinguishable series of downlink traffic volumes, (2) an attacker can extract the traffic volume of the target device from the DCI (Downlink Control Information) by linking the RNTI with the target device's TMSI, even if it may contain data other than video, and (3) the DCI is exposed in the wireless section without encryption. To block the video identification attack described above, the present invention proposes a technique for defending against the attack by eliminating the cause of the wireless section, which is generated by the MNO (Mobile Network Operator), that allows an attacker to link the RNTI and TMSI, which are different identifiers of the target device. Prior art literature

[0004] Ran Dubin, Amit Dvir, Ofir Pele, and Ofer Hadar. I Know What You Saw Last Minute-Encrypted HTTP Adaptive Video Streaming Title Classification. IEEE Transactions on Information Forensics and Security, 12(12):3039-3049, 2017. Jiaxi Gu, Jiliang Wang, Zhiwen Yu, and Kele Shen. Walls have ears: Traffic-based side-channel attack in video streaming. In IEEE INFOCOM 2018-IEEE Conference on Computer Communications, pages 1538-1546. IEEE, 2018. The problem to be solved

[0005] The objective of the present invention is to prevent an attacker in a mobile communication system from connecting an observed RNTI (Radio Network Temporary Identifier) ​​to the TMSI (Temporary Mobile Subscriber Identity) of a target device, thereby blocking the capture of traffic volume by an attacker. means of solving the problem

[0006] A method for preventing user identifier mapping in a target device of a mobile communication system according to an embodiment of the present invention comprises, when establishing a wireless connection in the target device, receiving an encrypted RRC Connection Reconfiguration message from a base station; receiving a new RNTI (Radio Network Temporary Identifier) ​​issued by the base station in response to the RRC Connection Reconfiguration message in the target device; and using the new RNTI in the target device.

[0007] The step of receiving the above message may involve receiving the encrypted RRC connection reconfiguration message at the base station after establishing a security context when establishing a wireless connection at the target device.

[0008] The above-mentioned step of using the target device can prevent the target device's RNTI and TMSI (Temporary Mobile Subscriber Identity) from being mapped by an attacker by using the new RNTI while the target device handovers to the same cell.

[0009] In addition, the method for preventing user identifier mapping in a target device of a mobile communication system according to an embodiment of the present invention may further include the step of processing a wireless connection reset procedure and additionally transmitting RRC connection reconfiguration / reconfiguration complete messages to the base station using the new RNTI in the target device.

[0010] A method for preventing user identifier mapping in a base station of a mobile communication system according to another embodiment of the present invention comprises, when establishing a wireless connection of a target device at a base station, a message transmission step of transmitting an encrypted RRC Connection Reconfiguration message to the target device, and an RNTI transmission step of transmitting a new RNTI (Radio Network Temporary Identifier; wireless network temporary identifier) ​​generated by the RRC Connection Reconfiguration message at the base station to the target device, wherein the target device uses the new RNTI.

[0011] The above message transmission step may, when establishing a wireless connection at the target device, establish a security context and then transmit the RRC connection reconfiguration message encrypted at the base station to the target device.

[0012] A user identifier mapping prevention system for preventing mapping of a user identifier in a target device of a mobile communication system according to an embodiment of the present invention comprises: a message unit that receives an encrypted RRC Connection Reconfiguration message from a base station when establishing a wireless connection in the target device; a receiver unit that receives a new RNTI (Radio Network Temporary Identifier) ​​issued by the base station in response to the RRC Connection Reconfiguration message in the target device; and a processing unit that uses the new RNTI in the target device.

[0013] When the above message unit establishes a wireless connection at the target device, after establishing a security context, the encrypted RRC connection reconfiguration message can be received at the base station.

[0014] The processing unit above can ensure that the target device is handed over to the same cell and that the new RNTI is used to prevent the RNTI of the target device from being mapped to the TMSI (Temporary Mobile Subscriber Identity) by an attacker.

[0015] The above processing unit can process the additional transmission of RRC connection Reconfiguration / Reconfiguration Complete messages to the base station and the wireless connection reset procedure using the new RNTI from the target device. Effects of the invention

[0016] According to an embodiment of the present invention, an attacker's attack can be defended by preventing an attacker in a mobile communication system from connecting an observed RNTI (Radio Network Temporary Identifier) ​​to the TMSI (Temporary Mobile Subscriber Identity) of a target device, thereby blocking the capture of traffic volume by the attacker. Brief explanation of the drawing

[0017] Figure 1 illustrates an example of the configuration and protocol stack of an LTE network. Figure 2 is illustrated to explain an example of a video identification attack. FIG. 3 illustrates a flowchart of the operation of a method to prevent user identifier mapping in a target device of a mobile communication system according to an embodiment of the present invention. Figure 4 illustrates the overhead of the proposed mitigation method according to an embodiment of the present invention. FIG. 5 illustrates an operation flowchart of a method to prevent user identifier mapping in a base station of a mobile communication system according to another embodiment of the present invention. FIG. 6 is a block diagram illustrating the detailed configuration of a user identifier mapping prevention system in a target device of a mobile communication system according to an embodiment of the present invention. Specific details for implementing the invention

[0018] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0019] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0020] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0021] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. Identical components in the drawings are denoted by the same reference numerals, and redundant descriptions of identical components are omitted.

[0023] Embodiments of the present invention are characterized by preventing an attacker from associating an observed RNTI (Radio Network Temporary Identifier) ​​with the target device's TMSI (Temporary Mobile Subscriber Identity), thereby blocking the capture of traffic volume.

[0024] The video identification attack presented in the LTE network utilizes the fact that (1) each video stream generates a series of distinguishable downlink traffic volumes, (2) the attacker can connect the RNTI to the target device's TMSI to extract the target device's traffic volume from the DCI (Downlink Control Information) even if it contains data other than video, and (3) the DCI is exposed to the wireless section without encryption.

[0025] (1) To block the process, a Streaming Service Provider can block the attack by removing distinguishable traffic patterns for each video. Existing technologies use the following approaches: 1) constant bitrate through rate throttling, 2) adding noise or padding to each streaming chunk, and 3) randomly changing the size of each chunk. However, deploying these approaches to wireless networks has limitations for operational reasons. Increasing the size of video chunks requires a larger number of chunks to play the same video, which degrades video quality. Furthermore, users tend to be sensitive to mobile data usage over mobile networks, which affects mobile phone usage charges. For example, existing technologies suggest adding noise at a volume more than double that of the original video, but this policy causes the problem of depleting a user's monthly data usage three times faster.

[0026] (3) To block the process, there is a method to encrypt DCI. Considering that a series of traffic volumes are obtained through DCI decoding, DCI encryption can be a method to eliminate the root cause. However, DCI is transmitted over the air via wireless signals every 1 ms, which inevitably involves a large number of decoding and encoding processes. In addition, introducing encryption to the non-secure protocol layer requires solving complex problems such as design selection using symmetric or asymmetric key encryption and the overhead of key management. Therefore, it must entail changes that hinder LTE protocol design.

[0027] Accordingly, the present invention proposes a technique for blocking the (2) process, and the present invention will be described in detail below with reference to FIGS. 1 to 5.

[0029] Figure 1 illustrates an example of the configuration and protocol stack of an LTE network.

[0030] As illustrated in FIG. 1, an LTE network consists of a core network of a User Equipment (UE, hereinafter referred to as 'target device') that provides mobile communication services to an end user, an eNodeB (evolved Node B; eNB, or base station) that provides wireless connectivity, and an EPC (Evolved Packet Core) that provides data services while managing user registration and mobility.

[0031] At this point, the transmission of video data from a video service provider (e.g., Netflix, YouTube, etc.) to a target device involves the following steps. The EPC gateway first receives video packets from the streaming service provider (or video service provider). Then, it transmits the video packets toward the eNB to which the target device is connected, and the eNB encapsulates the received packets and transmits them to the target device via a wireless channel.

[0032] At this time, multiple identifiers are assigned to the target device to ensure proper data delivery to the designated target device. The eNB to which the target device is connected assigns a Radio Network Temporary Identifier (RNTI) to the target device, and the EPC assigns this as a Temporary Mobile Subscriber Identity (TMSI). Using these identifiers, the EPC and eNB can not only deliver data to the correct recipient but also manage user-specific cryptographic keys for secure data transmission. Since the RNTI is a temporary yet unique identifier assigned by the eNB to the connected target device, the eNB distinguishes the user from other connected target devices. The RNTI is valid only when the target device is connected to the eNB. Similarly, the TMSI is a unique identifier managed by the EPC that is newly assigned when the target device registers with the LTE network.

[0033] A Radio Access Network (RAN) refers to the network between the target device and the connected eNB to which control messages and user data traffic are transmitted. Control messages and user data are transmitted through the LTE protocol stack. Control messages and user data traffic are encapsulated at the eNB through multiple layers. They are encrypted at the Packet Data Convergence Protocol (PDCP) layer, segmented at the Radio Link Control (RLC) layer, scheduled at the Medium Access Control (MAC) layer, and transmitted through the physical layer (PHY).

[0034] The Radio Resource Control (RRC) protocol defines methods for generating control messages that manage all radio connections (e.g., methods for establishing new connections or exchanging encryption algorithms). For example, when a target device requests a new connection to an eNB, the eNB responds with an RRC connection establishment message to convey radio configuration information. When there is no traffic between the eNB and the target device for a specific period, the eNB terminates the connection and sends an RRC disconnection message to conserve network resources as well as the target device's battery. If communication is required later, the connection is re-established.

[0035] A fundamental characteristic of wireless communication in LTE networks is that signals are broadcast to devices via various radio frequencies called channels. These channels serve as information sources from which each target device selectively retrieves its own data from the broadcast signal. At the physical layer, target devices are instructed on how to retrieve control information via the Physical Downlink Control Channel (PDCCH) and how to retrieve user data via the Physical Downlink Shared Channel (PDSCH).

[0036] At this time, the PDCCH provides multiple downlink control information (DCI; multiple DCIs). The DCI includes 1) a resource block allocated to a radio frame indicating the frequency and timing at which the target device must retrieve data, 2) a modulation coding scheme for decoding the allocated block, and 3) Cyclic Redundancy Check (CRC) bits masked by RNTI. The DCI is transmitted for every LTE subframe (i.e., 1ms). The PDCCH is an unencrypted channel in which the DCIs of all LTE users on the same carrier frequency are exposed to the public. Therefore, a single target device can decode all DCIs from the same PDCCH.

[0037] Furthermore, given that LTE networks allow all target devices sharing the same eNB to retrieve other users' data from the PDSCH, it is essential to provide confidentiality and integrity protections that ensure only legitimate users can access their data. In LTE networks, data integrity checks and encryption are performed at the PDCP layer. However, since the headers of all protocol layers below the PDCP layer are not encrypted, the header content of video streaming traffic volumes is visible to anyone. Accordingly, previous research addressed privacy threats in mobile communication networks that allow attackers to track user identities and locations. In this regard, RNTIs serve to mitigate privacy threats because they are temporary identifiers randomly assigned to each wireless connection. However, since eNBs assign multiple RNTIs to the same user over time, it becomes difficult for attackers to track a specific user based solely on a given RNTI without supplementary information.

[0038] In LTE Release 10, 3GPP introduced Carrier Aggregation (CA) technology, which utilizes multiple carrier frequencies simultaneously for data transmission. It is designed to provide more bandwidth per user by allocating multiple frequency bands to the same user. An eNB is often composed of multiple cells, each involving the transmission of radio signals within a designated frequency band. A primary cell (PCell) is the first cell that a target device connects to in order to establish a connection and exchange control messages. In the eNB used by the target device, all remaining cells become secondary cells (SCells). The basis of CA technology is to use PCells first for data transmission and then utilize SCells later when large amounts of data need to be delivered. CA execution is managed at the MAC layer, and packets from the upper layer are multiplexed and transmitted through the frames of PCells and SCells.

[0040] Figure 2 is illustrated to explain an example of a video identification attack.

[0041] Referring to Figure 2, a video identification attack is described as a threat to the critical personal information of a target device. The attack can be linked to other vulnerabilities in the mobile network to disclose the victim's identity or location. In particular, the attacker physically locates a series of users (or target devices or victims) who have watched a specific video and attempts an attack scenario targeting all target devices (UEs) of the eNB.

[0042] For example, in an attack scenario, the attacker (1) collects the TMSI and RNTI of the target device (UE) at the base station where the attacker is located, (2) identifies the RNTI streaming the target video through a video identification attack for each TMSI corresponding to the victim's UE, (3) forces the victim to connect to a fake base station (FBS), and (4) sends a fake emergency alert to the victim. By design, the victim's UE sounds an alarm for each emergency alert message (SIB message) to reveal its actual presence at the scene.

[0043] To explain the process of connecting the victim to a fake base station in more detail, the attacker performs a video identification attack to view the target video, obtains the RNTI of the target device (UE) that shares the same eNB as the attacker, and uses the obtained RNTI to inject a manipulated RRC Connection Release Message into the victim UE. The designated action of the UE upon receiving the RRC Connection Release Message is to immediately release the existing connection. Additionally, the attacker forges the redirectedCarrierInfo and idleModeMobilityControlInfo fields of the RRC Connection Release Message to specify the next frequency to connect to, thereby causing the target UE to disconnect from the legitimate eNB and move to the fake base station.

[0044] The aforementioned attack scenario is possible without the assistance of an MNO (Mobile Network Operator), and the victim cannot block the reception of the highest level of emergency alerts. Accordingly, unlike previous attacks that used fake base stations to broadcast fake SMS messages to all UEs, the end-to-end attack presented in Fig. 3 represents a targeted attack that sends emergency SMS messages to specific individuals watching a video on the attacker's target list.

[0046] FIG. 3 illustrates an operation flowchart of a method to prevent user identifier mapping in a target device of a mobile communication system according to an embodiment of the present invention, and FIG. 4 shows the overhead of a proposed mitigation method according to an embodiment of the present invention.

[0047] A method for preventing user identifier mapping in a target device of a mobile communication system according to an embodiment of the present invention is intended to block a video identification attack illustrated in FIG. 2, and aims to prevent the extraction (or capture) of traffic volume by an attacker by making it impossible for an attacker to connect the observed RNTI to the victim's TMSI.

[0048] Referring to FIG. 3, in step S310, a method for preventing user identifier mapping in a target device of a mobile communication system according to an embodiment of the present invention receives an encrypted RRC Connection Reconfiguration message from a base station (eNB) when establishing a wireless connection in the target device (UE). More specifically, the target device (UE) uses the first assigned RNTI that can be traced by an attacker. At this point, step S310, when establishing a wireless connection in the target device (UE), establishes a security context, receives an encrypted RRC Connection Reconfiguration message from the base station, and causes the base station (eNB) to issue a new RNTI through the encrypted RRC Connection Reconfiguration message.

[0049] In step S320, a new RNTI (Radio Network Temporary Identifier) ​​issued by the base station (eNB) via an RRC connection reconfiguration message is received. At this time, the base station (eNB) issues a new RNTI for the target device (UE) via the RRC connection reconfiguration message.

[0050] Subsequently, in step S330, the new RNTI is used on the target device (UE).

[0051] Step S330 is characterized by the target device (UE) taking over to the same cell and using a new RNTI to prevent the target device (UE)'s RNTI and TMSI (Temporary Mobile Subscriber Identity) from being mapped by an attacker.

[0052] The above-described method induces a target device (UE) to use a new RNTI through a handover to the same cell. The method for preventing user identifier mapping in a target device of a mobile communication system according to an embodiment of the present invention may further include a step (not shown) of additionally transmitting RRC connection reconfiguration / reconfiguration complete messages and processing a wireless connection reset procedure. Accordingly, the method for preventing user identifier mapping in a target device of a mobile communication system according to an embodiment of the present invention can defend against all attacks utilizing the mapping of RNTI and TMSI, such as location tracking attacks and image identification attacks.

[0054] A method for preventing user identifier mapping in a mobile communication system according to an embodiment of the present invention implemented the proposed defense technique in a base station (eNB) running on USRP B210 by modifying an open source LTE network. Approximately 70 lines of code were configured in the srseNB, mainly related to the RNTI reallocation step. The present invention used five UEs from three different baseband manufacturers and verified that the implemented defense technique operated smoothly without any changes to the UEs.

[0055] To evaluate the overhead of the proposed method, the present invention measured the time interval between the reception of the RRC connection reconfiguration message and the establishment of a wireless connection with the new RNTI, and this interval represents the additional processing time introduced by the proposed mitigation measure. Referring to Figure 4, it can be seen that the average overhead of 30 tests is between 7.38 and 35.7 ms for five different UEs. This overhead represents approximately 4 to 21% of the average latency (168.7 ms) of LTE service deployment by major U.S. operators. It should be noted that this mitigation imposes performance overhead but does not require any changes to existing UEs.

[0057] FIG. 5 illustrates an operation flowchart of a method to prevent user identifier mapping in a target device of a mobile communication system according to an embodiment of the present invention.

[0058] A method for preventing user identifier mapping in a base station of a mobile communication system according to another embodiment of the present invention is also intended to block the video identification attack illustrated in FIG. 2, and aims to prevent the extraction (or capture) of traffic volume by an attacker by making it impossible for an attacker to connect the observed RNTI with the victim's TMSI.

[0059] Referring to FIG. 5, in step S510, a method for preventing user identifier mapping at a base station of a mobile communication system according to another embodiment of the present invention transmits an encrypted RRC Connection Reconfiguration message from the base station (eNB) to the target device when establishing a wireless connection at the target device (UE). More specifically, the target device (UE) uses the first assigned RNTI that can be traced by an attacker. At this point, when establishing a wireless connection at the target device (UE), the base station establishes a security context, transmits the encrypted RRC Connection Reconfiguration message to the target device, and the base station (eNB) issues a new RNTI through the encrypted RRC Connection Reconfiguration message.

[0060] Subsequently, in step S520, the base station transmits a new RNTI generated by an RRC connection reconfiguration message to the target device. At this time, the base station (eNB) issues a new RNTI for the target device (UE) through an RRC connection reconfiguration message.

[0061] Accordingly, the target device uses a new RNTI received from the base station, and the present invention is characterized by the target device (UE) taking over to the same cell and using the new RNTI to prevent the target device (UE)'s RNTI and TMSI (Temporary Mobile Subscriber Identity) from being mapped by an attacker.

[0062] The above-described method induces a target device (UE) to use a new RNTI through a handover to the same cell. A method for preventing user identifier mapping at a base station of a mobile communication system according to another embodiment of the present invention may further include a step (not shown) of additionally transmitting RRC connection reconfiguration / reconfiguration complete messages and processing a wireless connection reset procedure. Accordingly, a method for preventing user identifier mapping at a base station of a mobile communication system according to another embodiment of the present invention can defend against all attacks utilizing the mapping of RNTI and TMSI, such as location tracking attacks and image identification attacks.

[0064] FIG. 6 is a block diagram illustrating the detailed configuration of a user identifier mapping prevention system in a target device of a mobile communication system according to an embodiment of the present invention, and represents the conceptual configuration of a server or system that performs a user identifier mapping prevention method in a mobile communication system.

[0065] Referring to FIG. 6, a user identifier mapping prevention system in a target device of a mobile communication system according to an embodiment of the present invention prevents an attacker from connecting an observed RNTI (Radio Network Temporary Identifier) ​​to the TMSI (Temporary Mobile Subscriber Identity) of the target device, thereby blocking the capture of traffic volume by an attacker.

[0066] To this end, in a mobile communication system according to an embodiment of the present invention, a user identifier mapping prevention system (600) includes a message unit (610), a receiving unit (620), and a processing unit (630).

[0067] The message unit (610) receives an encrypted RRC Connection Reconfiguration message from the base station (eNB) when establishing a wireless connection at the target device (UE). More specifically, the target device (UE) uses the first assigned RNTI that an attacker can trace. At this point, when establishing a wireless connection at the target device (UE), the message unit (610) establishes a security context, then receives an encrypted RRC Connection Reconfiguration message from the base station, and causes the base station (eNB) to issue a new RNTI through the encrypted RRC Connection Reconfiguration message.

[0068] The receiver (620) receives a new RNTI (Radio Network Temporary Identifier) ​​issued by the base station (eNB) via an RRC connection reconfiguration message. At this time, the base station (eNB) issues a new RNTI for the target device (UE) via the RRC connection reconfiguration message.

[0069] The processing unit (630) uses a new RNTI in the target device (UE).

[0070] The processing unit (630) is characterized by the target device (UE) being transferred to the same cell and using a new RNTI to prevent the target device (UE)'s RNTI and TMSI (Temporary Mobile Subscriber Identity) from being mapped by an attacker.

[0071] The above method induces the target device (UE) to use a new RNTI through a handover to the same cell, and the user identifier mapping prevention system (600) in the target device of the mobile communication system according to an embodiment of the present invention can process additional transmission of RRC connection reconfiguration / reconfiguration complete messages and wireless connection reconfiguration procedures through the processing unit (630). Accordingly, the user identifier mapping prevention system (600) in the target device of the mobile communication system according to an embodiment of the present invention can defend against all attacks utilizing the mapping of RNTI and TMSI, such as location tracking attacks and image identification attacks.

[0073] Even though the description of the system in FIG. 6 has been omitted, each constituent means constituting FIG. 6 may include all the contents described in FIG. 1 to FIG. 5, which is obvious to those skilled in the art engaged in this technical field.

[0075] The system or device described above may be implemented as a hardware component, a software component, and / or a combination of a hardware component and a software component. For example, the device and component described in the embodiments may be implemented using one or more general-purpose or special-purpose computers, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a Field Programmable Gate Array (FPGA), a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing unit may execute an operating system (OS) and one or more software applications executed on said operating system. Additionally, the processing unit may access, store, manipulate, process, and generate data in response to the execution of the software. For ease of understanding, the processing unit may be described as being used as a single unit, but those skilled in the art will understand that the processing unit may include multiple processing elements and / or multiple types of processing elements. For example, the processing unit may include multiple processors or one processor and one controller. Additionally, other processing configurations, such as parallel processors, are also possible.

[0077] Software may include computer programs, code, instructions, or a combination of one or more of these, and may configure a processing unit to operate as desired or command the processing unit independently or collectively. Software and / or data may be permanently or temporarily embodied in any type of machine, component, physical device, virtual equipment, computer storage medium or device, or transmitted signal wave so as to be interpreted by the processing unit or to provide instructions or data to the processing unit. Software may be distributed over networked computer systems and may be stored or executed in a distributed manner. Software and data may be stored on one or more computer-readable recording media.

[0079] The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either alone or in combination. The program instructions recorded on the medium may be those specifically designed and configured for the embodiment, or they may be those known and available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floptical disks; and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include machine code, such as that generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. The hardware devices described above may be configured to operate as one or more software modules to perform the operation of the embodiment, and vice versa.

[0081] Although the embodiments have been described above with reference to limited examples and drawings, those skilled in the art can make various modifications and variations from the description above. For example, suitable results can be achieved even if the described techniques are performed in a different order than described, and / or the components of the described system, structure, device, circuit, etc. are combined or assembled in a form different from described, or replaced or substituted by other components or equivalents.

[0083] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims set forth below.

Claims

Claim 1 A method for preventing user identifier mapping that induces a target device (UE) to use a new RNTI through a handover to the same cell of a mobile communication system, comprising: a message receiving step of receiving an encrypted RRC Connection Reconfiguration message from a base station when establishing a wireless connection at the target device; and an RNTI receiving step of receiving a new RNTI (Radio Network Temporary Identifier) ​​issued by the base station in response to the RRC Connection Reconfiguration message at the target device. and includes a usage step of using the new RNTI at the target device, and further includes a processing step of processing a wireless connection reset procedure and additionally transmitting RRC connection Reconfiguration / Reconfiguration Complete messages to the base station using the new RNTI at the target device, wherein the message receiving step, when establishing a wireless connection at the target device, after establishing a security context, receives the encrypted RRC connection reconfiguration message from the base station, and causes the base station to issue the new RNTI for the target device through the encrypted RRC connection reconfiguration message, and the usage step involves the target device being handed over to the same cell and using the new RNTI to allow an attacker to [use] the RNTI and TMSI (Temporary Mobile Subscriber Identity;A method for preventing user identifier mapping (Temporary Mobile Subscriber Identification) from being mapped, and blocking extraction based on an attacker using the RNTI to identify the traffic volume included in the Downlink Control Information (DCI) and associating it with the TMSI of the target device; wherein the user identifier mapping prevention method is characterized by adding a process of handing over to the same cell using the RRC connection reconfiguration / reconfiguration completion message after the creation of a security context during the initial connection process, and transmitting the RNTI over an encrypted channel to make mapping between the TMSI and RNTI impossible; wherein the target device is induced to use the new RNTI through a process of handing over to the same cell after using the first assigned RNTI that an attacker can trace, and receiving the new RNTI issued by the base station through the encrypted RRC connection reconfiguration message.

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