WO2018065711A1 - Method for registering user equipment in a communications network - Google Patents

Abstract

The invention relates to a method for registering user equipment (UE) in a communications network, said network comprising a mobility management entity (MME) and a home subscriber server (HSS), said method, implemented by the management entity, comprising: a step (E0) of receiving a request, from the user equipment, for attachment to the network; a step (E4) of sending an identification request to the user equipment; a step (E5) of receiving an identification response comprising an encrypted value (C) for the subscriber server, said encrypted value being based on an identifier of the user equipment, and a verification value (V) based on said identifier; a step (E6) of sending a vector authentication request to the home subscriber server, the request comprising the encrypted value; a step (E9) of receiving an authentication response comprising the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value; and a step (E10) of verification, by means of the verification value, that the identifier of the user equipment, received from the subscriber server, corresponds to the identifier used to calculate the control value.

Description

 Method for registering a user equipment in a communication network

The present invention relates to the field of access to a mobile communication network, and more particularly the security during access to this network.

 In the context of 3G and 4G mobile networks, 3GPP ("Third

Generation Partnership Project ") has defined protocols to ensure the security of a client's access to a mobile network. In particular, the protocols "UMTS AKA" (of the English "Universal Mobile Telecommunications System" and "Authentication and Key Agreement"), and "EPS AKA" (of the English "Evolved Packet System") describe a mutual authentication between the network and the client, and the establishment of session keys to ensure the confidentiality and integrity of the data exchanged between the client and the network when accessing the latter.

 However, some attacks are likely to undermine the security offered by mutual authentication, specifically to undermine the privacy of a client.

 AKA protocols are implemented after the network has received a client request for network attachment. Such an attachment request involves sending a client identifier into the network. Such an identifier, which identifies the subscription of the client to the network is either a permanent identifier called "IMSI" (of the English "International Mobile Subscriber Identity"), or a temporary identifier called "TMSI" ("Temporary Mobile Subscriber Identity") in the UMTS AKA protocol and GUTI (Globally Unique Temporary UE Identity) in the EPS AKA protocol.

 The IMSI is a unique number, stored in a security element ("Secure Element" in English), for example a UICC / USIM card (for "Universal Integrated Circuit Card / Universal Subscriber Identity Module") included in such a user equipment a mobile terminal, which allows the mobile network to identify the customer as a subscriber. This number is known to the network and used to initiate the mechanism of mutual authentication and key generation as defined in the AKA protocols. The network attachment procedure, and therefore the authentication protocols, attempt to minimize the clear exchange of the IMSI identifier on the radio interface by using temporary identifiers. Indeed, for security reasons the IMSI is transport as rarely as possible on the radio interface: to prevent an attacker does not intercept and use it to trace the movements of this client.

Temporary identifiers are assigned and modified by the network once the client is authenticated. Thus, before using a temporary identifier, the client must have made a first authentication using its permanent identifier IMSI. During this first authentication, the IMSI is then transmitted in clear on the radio channel between the user equipment and a network equipment. A risk of interception of the permanent identifier IMSI exists. There are indeed tools capable of obtaining from a user equipment its IMSI identifier. Such a tool, called "IMSI Catcher", behaves like a false relay antenna, located between the user equipment and an antenna relay of an operator. The IMSI Catcher intercepts the traffic coming from the terminal and can thus recover the IMSI.

 Obtaining the IMSI identifier of a subscriber makes it possible to locate and trace it in its movements. This undermines the privacy of the subscriber (we speak of "privacy" in English) and also calls into question the anonymization of network access services.

One of the aims of the invention is to remedy the shortcomings / disadvantages of the state of the art and / or to make improvements thereto.

 To this end, the invention proposes a method of registering a user equipment in a communication network, said network comprising a management entity and a subscriber server, the method, implemented by the management entity. , comprising:

 a step of receiving a request for attachment to the network from the user equipment,

 a step of sending the user equipment an identification request,

 a step of receiving an identification response, comprising an encrypted value for the subscriber server, said encrypted value being a function of an identifier of the user equipment, and a verification value, a function of said identifier,

 a step of sending an authentication vector request to the subscriber server, the request comprising the encrypted value,

 a step of receiving an authentication response comprising the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value,

- A verification step by means of the verification value that the identifier of the user equipment received from the subscriber server corresponds to the identifier used to calculate the control value.

With the method described here, a unique subscriber identifier is no longer transmitted in clear on the radio channel but in encrypted manner. It is transmitted along with an appropriate verification value to enable the mobility management entity that belongs to a visited network to ensure that the user equipment that attaches to the network corresponds to a device. user whose identifier is transmitted to it by the subscriber server of the nominal network, or network "home" of the user equipment. Encryption is indeed performed in the nominal network, the decryption can only be performed by a server of the nominal network, here the subscriber server.

 Note that the method is implemented when the user equipment does not have a temporary identifier, or when the mobility management entity has failed to obtain, from a previous registration entity involved. in the previous registration of the equipment to the network and from a temporary identifier provided by the user equipment, the identifier of the user equipment.

 The method thus guarantees the non-location of a subscriber and his non-traceability during his travels. The method thus contributes to respect for the subscriber's private life.

 Furthermore, the mobility management entity of the visited network via which the user equipment registers in the network is capable of associating a stream received from the user equipment with a subscriber identifier received from a server. of the nominal network. It thus respects obligations inherent to the implementation of certain exceptional procedures, for example the legal listening in France.

 In an exemplary embodiment, the attachment request includes a value representative of a lack of possession of a temporary identifier by the user equipment.

 This example corresponds to the case where the user equipment does not have a temporary identifier. In this case, the identification and identification response request steps are implemented between the mobility management entity and a previous registration entity.

 In an exemplary embodiment, the identification response comprises an identifier of the nominal network.

 The presence of a nominal network identifier in the identification request sent by the user equipment enables the mobility management entity to identify the subscriber server to contact to obtain an identifier of the user equipment. . Indeed, it can not deduce this information from the identifier of the user equipment that it received encrypted.

 In an exemplary embodiment, the identification request comprises a hazard, said hazard being used by the user equipment to calculate the encrypted value and the verification value.

 This example avoids replay attacks in which an attacker transmits to the mobility management entity an identification response that it has previously intercepted on the radio channel, in order to obtain an authentication vector. .

In an exemplary embodiment, the encrypted value is also a function of an authentication message calculated from the identifier of the user equipment and the hazard. The authentication message thus calculated is intended to be verified by the subscriber server of the nominal network. This ensures that the user equipment has the authentication key used to calculate the authentication message and is associated by the server to the user equipment.

 The invention also relates to a method for registering a user equipment in a communication network, said network comprising a management entity and a subscriber server, the method implemented by the user equipment comprising:

 a step of sending the management entity an attachment request to the network,

a step of receiving an identification request,

 a step of calculating an encrypted value for the subscriber server and a verification value, said encrypted value being a function of an identifier of the user equipment, and said verification value being a function of said identifier and sending; an identification response including the encrypted value and the verification value.

 The invention also relates to a method for registering a user equipment in a communication network, said network comprising a management entity and a subscriber server, the method implemented by the subscriber server comprising:

 a step of receiving an authentication vector request from the management entity, said request comprising an encrypted value by the user equipment for the subscriber server, said encrypted value being a function of an identifier user equipment,

 a step of sending an authentication response comprising an authentication vector and the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value.

 In an exemplary embodiment, the encrypted value is a function of a hazard and an authentication message calculated by the user equipment from the identifier of the user equipment and the hazard, the method comprising a step of verifying the authentication message by means of an authentication key associated with the identifier of the user equipment.

 The invention also relates to a management entity of a communication network, said network comprising at least one user equipment and a subscriber server, said entity comprising:

 first reception means, arranged to receive an attachment request to the network from the user equipment,

first sending means, arranged to send the user equipment an identification request, second reception means, arranged to receive an identification response, said identification response comprising an encrypted value for the subscriber server, said encrypted value being a function of an identifier of the user equipment, and a value verification, function of said identifier,

 second sending means, arranged to send an authentication vector request to the subscriber server, the request comprising the encrypted value,

 third reception means, arranged to receive an authentication response comprising the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value,

 - Verification means, arranged to verify by means of the verification value that the identifier of the user equipment received from the subscriber server corresponds to the identifier used to calculate the control value.

 The invention also relates to a program for a management entity of a communication network, comprising program code instructions for controlling the execution of the steps of the method of registering a user equipment in a network, described previously, when the program is executed on said entity.

 The invention also relates to a user equipment in a communication network, said network comprising a management entity and a subscriber server, comprising:

 means of sending, arranged to send to the management entity a request for attachment to the network,

 reception means, arranged to receive an identification request,

 calculation and sending means, arranged to calculate an encrypted value for the subscriber server, said encrypted value being a function of an identifier of the user equipment, and a verification value according to said identifier and to send a an identification response comprising said encrypted value and said verification value.

 The invention also relates to a computer program on a data carrier and loadable in the memory of a user equipment, the program comprising portions of code for performing the steps of the method of recording a user equipment in a network as described above, when the program is executed on said user equipment.

 The invention also relates to a subscriber server in a communication network, said network comprising a management entity and at least one user equipment, comprising:

receiving means, arranged to receive an authentication vector request from the management entity, said request comprising a value encrypted by the user equipment for the subscriber server, said encrypted value being a function of an identifier of the user equipment,

 sending means arranged to send an authentication response comprising an authentication vector and the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value.

 The invention also relates to a computer program on a data carrier and loadable in the memory of a subscriber server, the program comprising portions of code for performing the steps of the method of recording a subscriber server. user equipment in a network as described above, when the program is executed on said user equipment.

 The invention also relates to a system for recording at least one user equipment in a communication network comprising:

 a management entity as described above,

 at least one user equipment as described above, and

 a subscriber server as described above.

Other features and advantages of the present invention will be better understood from the description and the appended drawings in which:

 FIG. 1 presents the steps of a method of recording in the network, according to an exemplary embodiment;

 - Figure 2 is a schematic representation of a user equipment, adapted to implement the recording method in the network, according to an exemplary embodiment;

 - Figure 3 is a schematic representation of a mobility management entity, adapted to implement the recording method in the network, according to an exemplary embodiment.

 - Figure 4 is a schematic representation of a subscriber server, adapted to implement the recording method in the network, according to an exemplary embodiment.

The steps of a protocol for registering a user equipment with a network, according to an exemplary embodiment, will now be described in relation to FIG.

A user (not shown in FIG. 1) is equipped with UE user equipment arranged to access a mobile network. The user equipment UE usually comprises a terminal and a security element ("Secure Element" in English), for example a UICC / USIM card (for "Universal Integrated Circuit Card / Universal Subscriber Identity"). Module "). Such a security element is designed to store and process sensitive data, for example a network access application and associated data (referred to as "credentials" in English), such as keys and cryptographic algorithms. Such data is intended to be used by a mutual authentication protocol with the network when accessing the network. The invention is not limited to a user equipment of this type and in another exemplary embodiment, the user equipment UE comprises a secure software area arranged to process the sensitive network access data.

 The architecture of the mobile network and the method of attachment to the network are illustrated here as part of an "EPS" type network (for "Evolved Packet System"). The invention is however not limited to this type of network and also applies to other types of mobile networks such as for example the "GPRS" (General Packet Radio Service) network, or UMTS (Universal Mobile Telecommunications System).

 An eNB base station is arranged to manage radio transmission and reception with the UE user equipment. The UE user equipment is for example a smartphone, a mobile phone, a tablet, etc.

 An MME mobility management entity is typically responsible for control in an EPC (Evolved Packet Core) network. It is in charge, among other things, of managing the signaling of the network and the user equipment UE, the establishment of the connections, the management of the mobility of the UE equipment and its authentication based on data obtained from a subscriber server HSS (or "AuC" for "Authentication Center" or authentication center). Mobility management, or handover, can involve several entities including an old_MME network registration entity, involved in the previous registration of the user equipment to the network. This registration entity is arranged to provide on request information on a context specific to the user equipment UE and created during the previous registration of the equipment in the network. This old_MME registration entity is for example an MME mobility management entity, or another local mobility management entity, or an SGSN gateway that provides mobility management functions in the case of a GPRS network. .

A service gateway S-GW (for "Serving Gateway") is arranged to route IP packets between the user equipment UE and the core network and a packet gateway P-GW (for "Packet Data Network Gateway") is arranged to provide connectivity to external networks. An identity registration network entity "EIR" (for "Equipment Identity Register") is arranged to store security and identification information relating to mobile terminals. It is thanks to this entity that an operator can block stolen mobile equipment. Finally, a PCRF (Policy and Charging) entity Rules Function ") is in charge of real-time management and control of a session and offers a payment and billing interface. The functions of the S-GW service gateway, the P-GW packet gateway, the EIR registration entity, the PCRF management entity, the conventional functions of the MME mobility management entity , the old_MME registration entity and the interfaces between the different entities are described in detail in the TS 23.401 specification. The service gateways S-GW, P-GW packets, the registration entity EIR and the management entity PCRF are not shown in FIG. 1 for reasons of readability.

 For network access purposes, the UE UE stores an authentication key, denoted K, shared with the subscriber server HSS. The authentication key K is intended to be used for the generation of authentication data and to derive keys such as encryption keys of the radio channel and integrity check. More precisely, the authentication key K is stored in the security element of the user equipment UE. The user UE UE also stores a public key pke of a pair of asymmetric encryption keys pke / ske. The secret key ske is held only by the subscriber server HSS while the associated public key pke is distributed to all the user equipments that are managed by the same subscriber server HSS.

 The subscriber server HSS is arranged to authenticate the UE user equipment that it manages. To this end, it accesses a subscriber base that includes all the authentication keys K of the user equipment that it manages, an authentication key being associated in this database with a permanent identifier associated with a piece of equipment. user. The subscriber server HSS also stores the asymmetric encryption key pair pke / ske. It distributes the public encryption key pke to all subscribers it manages.

 Some of the exchanges described below are consistent with those of the procedure for registering a mobile terminal in a network as described in TS 23.401, clause 5.3.2.1. In particular the messages exchanged, when they have the same name, and their parameters, are identical to those of the specification. They are not described in detail.

 In an initial step E0, the user equipment UE transmits on the radio channel an Attach Request attachment request received by the base station eNB and retransmitted in a retransmission step El to the mobility management entity MME.

The attachment request includes an identifier of the UE user equipment. This identifier is either a temporary identifier of the type "GUTI" (for "Globally Unique Temporary Identifier") if it has one, or a predetermined value NoID. In one As an example embodiment, the temporary identifier has never been used for an attachment to the network. A temporary identifier that has never been used for an attachment to the network ensures that the UE is not traceable. Indeed, in this case the temporary identifier is used once and only circulates once on the radio channel. Sending the predetermined value NoID indicates that the user UE does not have a temporary identifier or does not have one which has never been used. In another exemplary embodiment, corresponding to a UMTS network, the temporary identifier is of the type "TMSI"("Temporary Mobile Subscriber Identity").

 In a case where the user equipment UE already has a GUTI or TMSI type temporary identifier, it has been assigned to it during a previous attachment of the UE equipment to the network by the old_MME registration entity, involved in the previous attachment.

 When the user equipment UE already has a temporary identifier, in a sending step E2, the mobility management entity MME conventionally sends an identification request, Identification Request, to the service entity. old_MME record that allocated the temporary identifier to the UE.

The old_MME registration entity sends an identification response, Identification Response, to the MME mobility management entity in a response step E3. The identification response includes a context specific to the UE that includes a Perm _ro subscriber ID, which has been associated with the GUTI temporary identifier, as well as security information. In an exemplary embodiment, the permanent identifier Perm is the unique subscriber number IMSI (International Mobile Subscriber Identity). The IMSI is a unique number, stored in the security element of the UE; it allows the mobile network to identify the user of the UE as a subscriber. Since steps E2 and E3 are optional, since they are executed only when the user equipment UE has a temporary identifier, they appear in dashed lines in FIG.

In a case where the user UE was unknown to the old_MME registration entity, or when the attachment request sent by the UE in step E0 includes the predetermined value NoID, the entity MME mobility management sends to UE UE in a step E4 an identification request, Identification Request, relayed by the base station eNB. The identification request sent to the user equipment UE comprises a random value ¾. This request is intended to obtain in a secure manner the identifier Pernii _D of the subscriber, user of the UE equipment. The Rand randomness is intended to prevent replay attacks during which an attacker would send an identification message previously sent and intercepted.

The user equipment UE sends, in a response step E5, an identification response, Identification Response, which comprises a triple of noted values (C, V, HPLMNj _d ). The triplet includes an identifier HPLMN _id of the home network (Home Public Land Mobile Network), a first value C, a second value V. The nominal network HPLMN is the network to which subscriber has subscribed . In other words it is the subscription network, or the network that provides the service to the subscriber. The first value C is intended to transmit the identifier Perm _ro of the subscriber in encrypted manner. The second value V is a control value, intended to enable the mobility management entity MME to ensure that a permanent identifier received from the subscriber server HSS of the nominal network HPLMN _id corresponds to that which has been transmitted which has been used to calculate the first value C. The first and second values C, V, are calculated as follows:

- C = PKE.Enc (pke; H ₅ (K; R _id , Perm _id ), R _id , Perm _id ), where PKE.Enc represents an asymmetric encryption algorithm and H ₅ a hash function with secret key of type HMAC authentication message (for "Hash Message Authentication Code"). In an exemplary embodiment, the asymmetric encryption algorithm is RSA (for "River, Shamir and Adleman") and the hash function H ₅ is part of a set of standardized functions such as Millenage, or Tuak. The HMAC authentication message enables the HSS subscriber server to be assured that the UE has the authentication key K.

- V = H * (R _id , Perm _id ), where H * corresponds to a hash function, for example SHA-2 (for "Secure Hash Algorithm").

The first value C allows the user equipment UE to transmit its identifier Perm _id confidentially. Note that the mobility management entity MME can not access the permanent identifier Perm _id of the terminal UE, the latter being transmitted encrypted and the mobility management entity MME does not have the cryptographic material to decipher it. Only the subscriber server HSS of the nominal network of the user equipment UE, which holds the secret key ske associated with the public encryption key pke is arranged to decrypt the permanent identity Perm _id of the terminal UE.

The second value V is a verification value intended to enable the mobility management entity MME to verify that the permanent identifier Perm _id used to calculate the first value C received from the user equipment UE in the response message. , is the permanent identifier that it will receive from the subscriber server HSS in response to a next authentication data request. The identifier of the nominal network HPLMNa enables the mobility management entity MME to identify the subscriber server HSS associated with the user equipment UE without knowing the identifier Pernii _d thereof.

In a next step E6, the mobility management entity MME sends an authentication vector request to the subscriber server HSS associated with the network identifier HPLM _id . The authentication vector request comprises the first value C received previously.

In a subsequent processing and verification step E7, the subscriber server HSS decrypts the value C by applying the asymmetric decryption algorithm PKE.Dec by means of its secret key ske. It thus obtains the identifier Perm _id associated with the user equipment UE, the randomness R _id and the authentication message HMAC, H ₅ (K, R _id , Perm _id ). The subscriber server HSS then extracts from its subscriber base the authentication key K associated with the user equipment UE whose permanent identifier is Perm _id and checks the authentication message HMAC obtained by the decryption. For this purpose, it calculates a control value by applying the function H ₅ to the authentication key K that it has extracted from its database, to the random value R _id and to the permanent identifier Perm _id qu he obtained by deciphering the first value C received during the step E6. In other words, it calculates H ₅ (K _C , R _id , Perm _id ).

 If this value is not equal to the HMAC authentication message of the triple C received during the step E5 (branch 'nok' in FIG. 1), the process ends in a step E8 of completion. Indeed, in this case, the user UE has calculated the authentication message with an authentication key different from the key associated with it by the subscriber server HSS.

In the opposite case (branch 'ok' in FIG. 1), the data that the subscriber server HSS has received is consistent with data of a subscriber. In a next step E9 of calculating and sending an authentication vector, the subscriber server HSS calculates an AV authentication vector in accordance with the attachment procedure described in TS 33.102. The subscriber server HSS sends at the end of step E9 an authentication response, Authentication Vector Answer which includes the permanent identifier Perm _id of the user equipment UE and the authentication vector AV previously calculated.

In a verification step E10, the mobility management entity MME verifies that the permanent identifier Perm _id received from the subscriber server HSS in the authentication response during step E9 corresponds to the user equipment. UE that sent an identification response in step E5 for the current attachment request. For this purpose, the mobility management entity MME calculates H * (R _id , Perm _id ) from the identifier Pernii _d received and the hazard R _id . It then verifies that the calculated value is equal to the verification value V that it received from the user equipment during step E5.

In a first case (branch "ok" in FIG. 1) where the values are equal, this means that the permanent identifier Pernii _d received from the subscriber server HSS corresponds to the identifier of the UE UE received encrypted at during step E5. Thus, thanks to the attachment method described here, the permanent identifier Perm _id of UE UE is no longer transmitted in clear on the radio channel during the attachment procedure to the network.

In a second case (branch 'nok' in FIG. 1) where the values are different, indicating that the permanent identifier Perm _id received from the subscriber server does not correspond to the identifier which was used to calculate the value of verification V, the process stops in a step El 1 end.

Thus, the security, highlighted by the authentication protocols, does not have the weakness inherent in a clear sending by the user equipment of the identifier Perm _id of the user equipment UE during attachment to the network. .

 In addition, the mobility management entity MME obtains the permanent identifier

Perm _id of the user UE UE of the subscriber server HSS of the nominal network of the user equipment UE. Thus, constraints inherent in exceptional procedures, such as legal listening procedures, are respected. Indeed, it is possible for the mobility management entity MME to associate a flow from a user equipment to a subscriber identifier. This information is necessary for the implementation of these exceptional procedures.

 The network attachment procedure continues, according to the end of step 5a and up to step 26 of the registration procedure described in TS 23.401, involving the S-GW service gateways. and packet P-GW, the registration entity EIR and the PCRF management entity not shown in FIG. 1. The execution of these steps of the registration procedure is represented in the figure by step E13 .

A mobility management entity, according to an exemplary embodiment, will now be described in connection with FIG. 2.

 An MME mobility management entity, is a network entity in charge of control in a mobile communication network. It is responsible for registering user devices, their authentication and their ability to be reachable.

The mobility management entity MME is a computer server that includes: a processing unit or processor 201, or "CPU" (of the "Central Processing Unit"), intended to load instructions in memory, to execute them, to perform operations;

 a set of memories, including a volatile memory 202, or "RAM" (for "Random Access Memory"), used to execute code instructions, store variables, etc., and a storage memory 203 of "EEPROM" type "(Electrically Erasable Programmable Read Only Memory). In particular, the storage memory 203 is arranged to store a software module comprising code instructions to implement those of the steps of the method of registering a user equipment in a network as described above which are executed by the MME mobility management entity;

 a set 203 of interfaces, arranged to communicate with entities of the network, such as the user equipment UE via the base station eNB, other management entities in the network, the subscriber server HSS.

 The mobility management entity MME also includes:

 a first reception module 205, arranged to receive a request for attachment to the network from the user equipment. The first reception module 205 is arranged to implement step E1 of the method described above;

 a first sending module 206, arranged to send the user equipment an identification request. The first sending module 206 is arranged to implement the step E4 of the recording method described in connection with Figure 5;

 a second reception module 207, arranged to receive an identification response, said identification response comprising an encrypted value C for the subscriber server, said encrypted value being a function of an identifier of the equipment; user. The second reception module 207 is also arranged to receive a verification value V, a function of said identifier. The second reception module 207 is arranged to implement the step E5 of the recording method described above;

 a second sending module 208, arranged to send an authentication vector request to the subscriber server HSS, the request comprising the encrypted value C. The second sending module 208 is arranged to implement the step E6 of the process described above;

a third reception module 209, arranged to receive an authentication response comprising the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value. The third receiving module 209 is arranged to implement step E9 of the recording method as previously described; and

 a verification module 210, arranged to verify by means of the verification value that the identifier of the user equipment received from the subscriber server corresponds to the identifier used to calculate the control value. The verification module 210 is arranged to implement the step E10 of the method described above.

 The set of interfaces 204, the first sending module 205, the first receiving module 206, the second receiving module 207, the second sending module 208, the third receiving module 209 and the checking module are preferably software modules comprising software instructions for implementing the steps of the method of registering a user equipment in a communication network that are executed by the mobility management entity MME.

 The invention therefore also relates to:

 a computer program comprising instructions for implementing the method for registering a mobile terminal as described above when this program is executed by a processor of the mobility management entity MME, and

 a readable recording medium on which is recorded the computer program described above. UE user equipment according to an exemplary embodiment, will now be described in connection with Figure 3.

UE user equipment usually comprises a mobile equipment equipped with a radio interface arranged to interface with a mobile communication network, and a security element ("Secure Element" in English), for example a UICC USIM card (for " Uni versai Integrated Circuit Card / Universal Subscriber Identity Module "). Such a security element is arranged to store and process sensitive data, such as keys and cryptographic algorithms. Such data and algorithms are intended to be used when registering the UE in the network, and in particular during the authentication procedure between the user equipment and the network. The interactions between the mobile terminal and the security element in the user equipment UE being very close during an access of the user equipment UE to the network and for reasons of readability, there is no distinction in the following. mobile equipment of the security element, which are thus grouped in the UE user equipment. The invention is not limited to a user equipment of this type and in another exemplary embodiment, the user equipment UE comprises a secure software area arranged to process the network access sensitive data.

 In the example described here, the user equipment UE comprises:

 a processing unit 301, or CPU, arranged to execute code instructions,

 a radio interface 302, arranged to interface with the mobile communication network;

a set of memories, including a volatile memory 303 of the RAM type, used to execute code instructions, store variables, etc., and a storage memory 304 of the flash memory or EEPROM type. The storage memory 304 is arranged to store data and applications. In particular, the storage memory 304 stores a recording software module in the network arranged to implement those of the steps of the recording method in the network described above which are implemented by the user equipment UE. The storage memory 304 also stores an authentication key K, an identifier of the nominal network HPLMN _{i (} j, a public key pke associated with a secret key ske held by the subscriber server HSS, and a value NoID intended to be sent by the user equipment in a network attachment request when the equipment does not have a temporary identifier;

 UE user equipment also includes:

 a sending module 305, arranged to send the management entity an attachment request to the network. The sending module 305 is arranged to implement the step E0 of the recording method as described above;

 a reception module 306, arranged to receive an identification request. The receiving module 306 is arranged to implement the step E4 of the method described above;

a calculation and sending module 307, designed to calculate an encrypted value for the subscriber server, said encrypted value being a function of an identifier of the user equipment, and a verification value that is a function of said identifier. The calculation and sending module 307 is also arranged to send an identification response comprising said encrypted value and said verification value. The calculation and sending module 307 is arranged to implement the step E5 of the recording method as described with reference to FIG. The sending module 305, the receiving module 306 and the calculating and sending module 307 are preferably software modules comprising software instructions for implementing the steps of the method of registering a user equipment in a device. communication network that are executed by the UE.

 The invention therefore also relates to:

 a computer program comprising instructions for implementing the method for registering a mobile terminal as described above when this program is executed by a processor of the user equipment UE, and

 a readable recording medium on which is recorded the computer program described above.

A subscriber server, according to an exemplary embodiment, will now be described in relation to FIG. 4.

 An HSS subscriber server is a computer server arranged to manage subscriber access data to a communication network. It is also designed to authenticate a user equipment when it accesses the network and to authenticate with this equipment.

 The HSS subscriber server includes:

 a processing unit or processor 401, intended to load instructions in memory, to execute them, to perform operations;

 a set of memories, including a volatile memory 402, or RAM, used to execute code instructions, store variables, etc., and a storage memory 403 of the EEPROM type. In particular, the storage memory 403 is arranged to store a software module comprising code instructions to implement those of the steps of the method of recording a user equipment in a communication network as described above which are executed by the HSS subscriber server. The subscriber server HSS is arranged to access a subscriber base 404 which includes network access data specific to each subscriber to the network. In particular, for each subscriber of the network, the subscriber server HSS stores an authentication key K of the subscriber. The subscriber server HSS also stores a pair of asymmetric encryption keys pke / ske. It distributes the pke public encryption key to all the subscribers it manages;

 a set of interfaces 405 arranged to communicate with entities of the network, for example the mobility management entity MME.

The HSS Subscriber Server also includes: a reception module 406, arranged to receive an authentication vector request from the management entity, said request comprising an encrypted value C by the user equipment for the subscriber server. The encrypted value is based on an identifier of the user equipment. The reception module 406 is arranged to implement the step E6 of the recording method described above;

 a sending module 407, arranged to send an authentication response comprising an authentication vector and the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value. The sending module 407 is arranged to implement step E9 of the recording method described in relation to FIG.

 In an exemplary embodiment, where the encrypted value is a function of a Rand randomness and an authentication message calculated by the user equipment from the identifier of the user equipment and the hazard, the server subscriber also includes a module (not shown in Figure 4) verification, arranged to verify the authentication message by means of an authentication key associated with the identifier of the user equipment.

 The interfaces 405, the reception module 406 and the sending module are preferably software modules comprising software instructions for implementing the steps of the method of registering a user equipment in a network as described above which are executed by the HSS subscriber server.

 The invention therefore also relates to:

 a computer program comprising instructions for implementing the method of registering a user equipment in a network as described above when this program is executed by a processor of the subscriber server HSS, and

 a readable recording medium on which is recorded the computer program described above.

The invention also relates to a recording system in a communication network. This system comprises at least one user equipment UE as described with reference to FIG. 3, an HSS subscriber server as described with reference to FIG. 4 and a mobility management entity as described in connection with FIG. 2. Such a system is arranged to implement the steps of the recording method as described above.

Claims

A method of registering a user equipment (UE) in a communication network, said network comprising a management entity (MME) and a subscriber server (HSS), the method, implemented by the entity management, including:  a step (E0) of receiving a request for attachment to the network from the user equipment,  a step (E4) of sending an identification request to the user equipment, a step (E5) for receiving an identification response, comprising an encrypted value (C) for the subscriber server, said encrypted value being a function of an identifier of the user equipment, and a verification value; (V), function of said identifier,  a step (E6) of sending an authentication vector request to the subscriber server, the request comprising the encrypted value,  a step (E9) of receiving an authentication response comprising the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value, a verification step (E10) by means of the verification value that the identifier of the user equipment received from the subscriber server corresponds to the identifier used to calculate the control value. 2. The method of claim 1, wherein the attachment request comprises a representative value (NoID) of a lack of possession of a temporary identifier by the user equipment. 3. Method according to one of the preceding claims, wherein the identification response comprises an identifier of the nominal network. 4. Method according to one of the preceding claims, wherein the identification request comprises a random (¾), said random being used by the user equipment to calculate the encrypted value and the verification value. 5. The method of claim 4 wherein the encrypted value is also a function of an authentication message calculated from the identifier of the user equipment and the random. A method of registering a user equipment (UE) in a communication network, said network comprising a management entity (MME) and a subscriber server (HSS), the method, implemented by the equipment user comprising:  a step (E0) of sending to the management entity an attachment request to the network, a step (E4) of receiving an identification request,  a step (E5) for calculating an encrypted value (C) for the subscriber server and a verification value (V), said encrypted value being a function of an identifier of the user equipment, and said verification value (V) being a function of said identifier and sending an identification response including the encrypted value and the verification value. A method of registering a user equipment (UE) in a communication network, said network comprising a management entity (MME) and a subscriber server (HSS), the method, implemented by the server subscribers including:  a step (E6) for receiving an authentication vector request from the management entity, said request comprising an encrypted value (C) by the user equipment for the subscriber server, said encrypted value; depending on an identifier of the user equipment,  - A step (E9) of sending an authentication response comprising an authentication vector and the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value. 8. The method of claim 7 wherein the encrypted value is a function of a random (R _id ) and an authentication message calculated by the user equipment from the identifier of the user equipment and the user. The method comprises a step of verifying the authentication message by means of an identification key associated with the identifier of the user equipment. 9. Management entity (MME) of a network, said network comprising at least one user equipment (UE) and a subscriber server (HSS), said entity comprising:  first reception means (205), arranged to receive an attachment request to the network from the user equipment,  first sending means (206), arranged to send to the user equipment an identification request, second reception means (207), arranged to receive an identification response, said identification response comprising an encrypted value (C) for the subscriber server, said encrypted value being a function of an identifier of the user equipment, and a verification value (V), a function of said identifier,  second sending means (208), arranged to send an authentication vector request to the subscriber server, the request comprising the encrypted value,  third receiving means (209), arranged to receive an authentication response comprising the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value,  - Verification means (210), arranged to verify by means of the verification value that the identifier of the user equipment received from the subscriber server corresponds to the identifier used to calculate the control value. A program for a management entity of a communication network, comprising program code instructions for controlling the execution of the steps of the method of registering a user equipment in a network, according to one of the claims. 1 to 5, when the program is executed on said entity. User equipment (UE) in a communication network, said network comprising a management entity (MME) and a subscriber server (HSS), comprising:  sending means (305), arranged to send to the management entity a request for attachment to the network,  reception means (306), arranged to receive an identification request, calculating and sending means (307), arranged to calculate an encrypted value for the subscriber server, said encrypted value being a function of an identifier of the user equipment, and a verification value depending on said identifier and for sending an identification response comprising said encrypted value and said verification value. 12. Computer program on a data medium and loadable in the memory of a user equipment, the program comprising portions of code for performing the steps of the method of registering a user equipment in a network according to the any one of claims 6, when the program is executed on said user equipment. A subscriber server (HSS) in a communication network, said network comprising a management entity (MME) and at least one user equipment UE, comprising: receiving means (406), arranged to receive an authentication vector request from the management entity, said request comprising an encrypted value (C) by the user equipment for the subscriber server, said encrypted value depending on an identifier of the user equipment,  sending means (407), arranged to send an authentication response comprising an authentication vector and the identifier of the user equipment obtained from the subscriber server by decryption of the encrypted value. 14. Computer program on a data medium and loadable in the memory of a subscriber server, the program comprising portions of code for performing the steps of the method of registering a user equipment in a network according to any one of claims 5, when the program is executed on said user equipment. 15. System for registering at least one user equipment in a communication network comprising:  a management entity (MME) according to claim 9,  at least one user equipment (UE) according to claim 11, and  a subscriber server (HSS) according to claim 13.