METHOD FOR MANAGING SECURITY INFORMATION IN A COMMUNICATION NETWORK, CORRESPONDING DEVICE, DEVICE FOR ACCESSING THE NETWORK AND COMPUTER PROGRAMS

Description

Field of invention

[0001] The field of the invention is that of communication networks, in particular wireless communication networks.

[0002] The invention relates to the management of security information in such a communication network, said security information being used to establish a secure connection between terminal equipment and access equipment to said network.

[0003] It is particularly useful for improving the security of home Wi-Fi networks, which are currently subject to increased risks of attack. Prior art and its drawbacks

[0004] Managing the security of home Wi-Fi networks is problematic. While corporate Wi-Fi networks can rely on strong authentication, the same is not true for home networks, whose security relies on the strength of a pre-shared Wi-Fi key (PSK) between an access device, or AP, and terminal devices, or STAs, that wish to connect to it.

[0005] However, using such a WiFi key today has the following disadvantages: Keys set by an equipment manufacturer or network operator are secure but difficult or impossible for a user to remember; keys changed by users often have a very low level of security; it is virtually impossible to revoke access granted to a guest on the home network.

[0006] Furthermore, the risk of attacks is increased today by the fact that graphics card processors or GPUs (for "Graphical Processing Unit" in English) have become powerful and fast enough that these attacks on WiFi keys can now be launched offline, based on a prior capture of WiFi traffic.

[0007] Document FR3032582, published in August 2016 by the INPI, discloses a method for managing the duration of a secure connection, which proposes a technique for evaluating the strength of a password and determining a validity period for this password and therefore for the connection based on the evaluated strength. However, this document does not teach a solution for managing a change of password or, more generally, security information shared by terminal equipment and access equipment to a communication network. Document EP 2 276 278 A1 published on January 19, 2011 discloses methods and apparatus for maintaining secure connections in a wireless communication network.

[0008] There is therefore a need for a technique for managing security information in a communications network, which does not have the drawbacks of the prior art.

[0009] Another need is for a technique for managing security information in a communications network that helps reduce the risk of attacks without making access to the network more restrictive for a user of terminal equipment. Statement of the invention

[0010] The invention meets this need by proposing a method for managing security information, called first security information, intended to be implemented to establish a secure connection between at least one terminal device and an access device to a communication network, said first security information being associated with a validity period, said method implemented by said access device and in that it comprises: Upon expiration of the validity period, obtaining a second security information and triggering a deactivation period for the first security information; If said terminal equipment is connected to the access equipment, transmitting to said terminal equipment a reauthentication command message comprising at least the second security information and a reauthentication period, said reauthentication period expiring before the end of said deactivation period for the first security information; and If a reauthentication request message is received from the terminal equipment before the expiration of the reauthentication period, reauthenticating the terminal equipment using the second security information without extinguishing the connection.

[0011] Thus, the invention is based on a completely new and inventive approach to securing a connection in a communications network, according to which security information shared by network access equipment and terminal equipment registered in the network is renewed regularly at the initiative of the access equipment. It also offers any terminal equipment connected to the network at the time of renewal the possibility of re-authenticating itself without disconnecting the network for a limited period of time where the first and second security information are simultaneously valid.

[0012] The security information is, for example, a key chosen by the access equipment or the terminal from a smaller dictionary than that commonly used in the prior art and it is associated with a validity period determined according to the robustness of the key. This validity period may be relatively short, and for example be between one day and a few weeks.

[0013] According to one aspect of the invention, the method comprises, following the triggering of the deactivation delay and upon receipt of a connection establishment request message from a terminal device comprising said first security information, a verification of at least one reconnection condition, said at least one condition comprising at least the non-expiration of a reconnection delay, said reconnection delay expiring at the earliest at the end of the deactivation delay of the first security information, and if said at least one reconnection condition is satisfied: establishing the connection of the terminal equipment on the basis of the first security information; and transmitting to said terminal equipment a reauthentication request message comprising at least the second security information and a reauthentication delay.

[0014] In this way, a terminal device already registered to the network before the renewal of the security information can continue for a certain period to connect to the network from the first security information. The access equipment takes advantage of the connection thus established to securely transmit the second security information to it. It then grants it a period for re-authentication, which can advantageously be configurable, begins to run upon transmission of the request message and does not expire before the first security information is deactivated.

[0015] According to another aspect of the invention, the reconnection timeout expires at the end of the deactivation timeout of the first security information.

[0016] A first condition to be satisfied is that the request to establish a connection occurs within the deactivation period of the first security information, that is to say while it is still active.

[0017] One advantage is that it does not require the access equipment to manage two security information at the same time, keys or passwords, and therefore two separate login procedures, for too long a period.

[0018] According to yet another aspect of the invention, the reconnection period expires at the end of a grace period triggered upon expiration of the deactivation period of the first security information.

[0019] If the first condition is not met, it is at least required that the request to establish a connection on the basis of the first security information occurs within a grace period which begins to run at the expiry of the deactivation period of this first security information.

[0020] One advantage of a longer period is that it makes the security information renewal process more flexible and allows more end devices to easily update their security information.

[0021] According to yet another aspect of the invention, said terminal equipment having been previously registered in the network in association with trusted information, said step of verifying at least one reconnection condition further verifies that said trusted information is positioned at a value " trustworthy ".

[0022] Thus, during the grace period, only terminal devices registered as trusted are able to reconnect to the network with the first security information. An advantage is to increase the security level by removing guest terminal devices that the network administrator has not granted this status.

[0023] According to yet another aspect of the invention, the method comprises determining a list of at least one terminal device registered in the network with the trust information set to the value “ trustworthy » prior to the triggering of the deactivation period of the first security information, and not having yet issued a connection request, and the sending of a notification message to said at least one terminal device before the expiry of the grace period.

[0024] One advantage is that the access equipment informs trusted end devices of the opportunity to easily update their security information before declaring the first piece of information permanently obsolete. Once the deadline has expired, they will have to reinitiate a full network registration procedure.

[0025] For example, communicating objects that are normally permanently connected to the network will receive the notification of security information change via the Wi-Fi network. For terminal equipment not connected to the Wi-Fi network, the access equipment, for example, has a mobile phone number associated with the terminal equipment and transmits this notification to it by SMS.

[0026] According to yet another aspect of the invention, upon expiration of the grace period, an additional grace period is triggered as long as the list is not empty.

[0027] This ensures that no trusted terminal equipment is forced to re-register, which would be cumbersome. Of course, it is possible to consider making the new grace period shorter than the previous one and also limiting the number of renewals to ensure a sufficient level of security.

[0028] The invention also relates to a computer program product comprising program code instructions for implementing a method for managing security information in a communication network as described above, when executed by a processor.

[0029] The invention also relates to a computer-readable recording medium on which is recorded a computer program comprising program code instructions for executing the steps of the management method according to the invention as described above.

[0030] Such a recording medium may be any entity or device capable of storing the program. For example, the medium may include a storage medium, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording medium, for example a USB flash drive or a hard disk.

[0031] On the other hand, such a recording medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means, so that the computer program contained therein is remotely executable. The program according to the invention may in particular be downloaded over a network, for example the Internet.

[0032] Alternatively, the recording medium may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the aforementioned management method.

[0033] The invention also relates to a device for managing security information, called first security information, intended to be implemented to establish a secure connection between at least one terminal device and an access device to a communication network, said first security information being associated with a first validity period.

[0034] Said device is configured to: Upon expiration of the first validity period, obtaining a second security information and triggering a deactivation period for the first security information; If said terminal equipment is connected to the access equipment, transmitting to said terminal equipment a reauthentication request message comprising at least the second security information and a reauthentication period, said reauthentication period expiring before the end of said deactivation period for the first security information; and If a reauthentication request message is received from the terminal equipment before the expiration of the reauthentication period, reauthenticating the terminal equipment using the second security information without extinguishing the connection.

[0035] More generally, such a device is capable of implementing a method for managing security information as described previously.

[0036] Advantageously, said device is integrated into equipment for accessing a communications network, for example a residential or corporate gateway.

[0037] The aforementioned access equipment, management device and corresponding computer program have at least the same advantages as those conferred by the management method according to the present invention.

[0038] Correlatively, the invention also relates to a method for managing a connection of terminal equipment to a communication network, comprising equipment for accessing said network, said connection being secured by first security information.

[0039] Said method is implemented by said terminal equipment and comprises: When connected to said network, receiving from said access equipment via a connection to the communication network a reauthentication command message, comprising at least a second security information and a reauthentication delay (less than or equal to a deactivation delay of the first security information, Sending, within the reauthentication delay, a reauthentication request message to said access equipment comprising the second security information, and recording the second security information in place of the first security information.

[0040] According to the invention, the terminal equipment adapts its behavior to update its connection information within the deactivation period set by the access equipment.

[0041] According to another aspect of the invention, the method comprises: When not connected to said network, receiving a security information change notification message via an interface with another communication network, said message comprising a reconnection time limit to said network, said time limit expiring at the earliest at the end of the deactivation time limit of the first security information, and sending a reconnection request message to the communication network within said time limit.

[0042] According to yet another aspect of the invention, the method further comprises determining a time of transmission of said reauthentication request message to said access equipment within the reauthentication period.

[0043] This embodiment applies advantageously to the case where the deactivation delay is common to all access equipment. The fact that the terminal equipment each determines its own time of transmission of its connection request, for example randomly, makes it possible to smooth the load at the level of the access equipment.

[0044] The invention also relates to a computer program product comprising program code instructions for implementing a method for managing a connection to a communications network as described above, when executed by a processor.

[0045] The invention also relates to a computer-readable recording medium on which is recorded a computer program comprising program code instructions for executing the steps of the management method according to the invention as described above.

[0046] Such a recording medium may be any entity or device capable of storing the program. For example, the medium may include a storage medium, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording medium, for example a USB flash drive or a hard disk.

[0047] On the other hand, such a recording medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means, so that the computer program contained therein is remotely executable. The program according to the invention may in particular be downloaded over a network, for example the Internet.

[0048] Alternatively, the recording medium may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the aforementioned management method.

[0049] The invention also relates to a device for managing a connection of terminal equipment to a communication network, comprising equipment for accessing said network, said connection being secured by first security information.

[0050] Said device is configured to: receiving a reauthentication command message from the access equipment via a connection to said network, said message comprising at least a second security information and a reauthentication period, said period expiring at the earliest at the end of the deactivation period of the first security information; and transmitting within the reauthentication period a reauthentication request message to said access equipment comprising the second security information.

[0051] More generally, such a device is capable of implementing a method for managing a connection as described previously.

[0052] Advantageously, said device is integrated into terminal equipment.

[0053] The aforementioned terminal equipment, connection management device and corresponding computer program have at least the same advantages as those conferred by the management method according to the present invention. List of figures

[0054] Other aims, characteristics and advantages of the invention will appear more clearly on reading the following description, given as a simple illustrative, and non-limiting, example, in relation to the figures, among which: [ Fig. 1 ] This figure schematically represents an example of a local communication network managed by access equipment, to which a plurality of terminal equipments are connected, according to one embodiment of the invention; [ Fig. 2 ]This figure represents in the form of a flowchart the different stages of the method for managing security information in a communication network, implemented by access equipment, according to one embodiment of the invention; [ Fig. 3 ] This figure represents in the form of a flowchart the different stages of the method for managing a secure connection to a communication network, implemented by terminal equipment, according to one embodiment of the invention; [ Fig. 4A ] This figure schematically represents the messages exchanged between network access equipment and terminal equipment following the renewal of security information according to a first exemplary embodiment of the invention; [ Fig. 4B ]This figure schematically represents the messages exchanged between network access equipment and terminal equipment following the renewal of security information according to a first second exemplary embodiment of the invention; [ Fig. 5 ] This figure schematically represents the verification of conditions for reconnecting terminal equipment to the communication network following the renewal of security information according to one embodiment of the invention; [ Fig. 6 ] This figure schematically represents an example of a time diagram of the exchanges between terminal equipment registered in the communication network and the access equipment to said network following the renewal of the security information according to one embodiment of the invention; [ Fig. 7 ]This figure provides a block diagram of equipment for accessing a communication network comprising a device for managing security information in a communication network implementing the method for managing security information of the figure 2 ; And [ Fig. 8 ] This figure provides a block diagram of terminal equipment comprising a device for managing a connection to a communication network, implementing the method for managing a connection to a communication network of the figure 3 . Detailed description of embodiments of the invention

[0055] The general principle of the invention is based on a regular renewal of security information shared by a network access device and a terminal device registered in the network, at the initiative of the access device. The invention also offers any terminal device connected to the network at the time of the change of security information, the possibility of re-authenticating itself without interruption of connection to the network during a limited time period where the old and the new security information are simultaneously valid.

[0056] In the remainder of the description, we will present in detail the case of a residential Wi-Fi communication network to which terminal equipment connects securely based on an exchange of security information, such as pre-shared keys or PSKs. Of course, the invention is not limited to this example and also relates to any other type of network, to which terminal equipment connects securely based on an exchange of security information. For example, the RC network is a corporate network, implementing Li-Fi technology or another type. The security information may be passwords or any other type of shared secret.

[0057] In relation to the figure 1 ,we consider a local communication network RC comprising access equipment PA, of the residential gateway type (for "home gateway", in English). Of course, the invention is not limited to this example and applies to any other type of access equipment to a wireless communication network, such as for example equipment of the Wifi repeater type (for "Wifi Range Extender", in English), which makes it possible to repeat a Wi-Fi signal further, for example to reach the end of a corridor in a building.

[0058] In the example of the figure 1 , we consider several terminal equipment or STA stations capable of connecting to the RC wireless communication network: A STA1 tablet, a STA2 mobile terminal, which also has a cellular interface; a STA1 communicating object, for example, a camera (for "webcam" in English); a STA3 laptop; a STA4 mobile terminal, which also has a cellular interface; and another STA5 mobile terminal, the usual equipment of a user who is an administrator of the RC network.

[0059] In the remainder of the description, it is considered that the domestic gateway PA, 10 incorporates a device 100 for managing security information (not shown in the figure 1 ) capable of implementing a method for managing security information according to an embodiment of the invention, which will now be described in relation to the figure 2 .

[0060] As is well known, the RC Wifi network is associated with a unique identifier, called SSID (for “Service Set Identifier”, in English), as specified by the IEEE 802.11 standard.

[0061] As is known, in a Wi-Fi network, the access equipment PA and a terminal equipment STA registered in the RC network share a secret, generally intelligible and in a non-digital way. According to the IEEE 802.11 standard, this is a shared security key PSK (for "Pre-Shared Key", in English), which is human-readable and comprises between 8 and 63 characters in ASCII format. A non-digital means of sharing is understood to mean that the parties do not obtain the key by an exchange of messages via an unsecured digital communication. For example, the PSK key is generally chosen by the manufacturer and written on the back of the residential gateway. The user of the terminal STA must enter it via an interface of the terminal so that the latter can establish a connection with the access equipment PA.

[0062] It should be noted, however, that an STA terminal can also connect to the access point PA using a protocol called WPS (for "Wifi Protected Setup", in English), intended to simplify the security configuration phase of a wireless network. According to this protocol, the access point AP transmits the PSK key to the STA terminal in an unsecured manner.

[0063] From this PSK key, the access equipment and the STA terminal equipment each generate another key called PMK (for "Pairwise Master Key" in English) using an algorithm specified by the IEEE 802.11 standard. From this PMK key, the PA and STA equipment exchange messages and derive other keys forming a set of security keys allowing a secure connection to be established between them. In this way, the PSK key is never exchanged in the network.

[0064] In the remainder of the description, JK will designate a set of keys derived from the PSK key and JK will invariably be used to designate a key from this set exchanged in a message between the access equipment PA and an STA terminal.

[0065] In the remainder of the description, we consider more particularly the case where the key PSK1 is not the one written by the manufacturer on the back of the housing of the residential gateway PA, but was chosen by a user or automatically by the gateway PA and was associated with a validity period DV1. For example, this validity period was determined according to a robustness of the key PSK1, using for example the solution of the prior art cited above. This robustness is evaluated according to an entropy of the key which makes it possible to estimate an “average lifespan before breaking” of this key, which is then divided by a factor of between 50 and 100 for greater security. It can be between 1 day and a few months.

[0066] At the end of the validity period DV1 associated with this first key PSK1 and detected in P20, a second key PSK2 is obtained in P21 and a delay DD for deactivating the first key PSK2 and therefore the first set of keys JK1 is triggered in P22.

[0067] For example, the deactivation time is: manually set, for example equal to 24 hours; or preferably, determined according to the DV1 validity period of the first key, and less than the validity period. For example, for a DV1 validity period of one week, a deactivation period of 24 hours would seem consistent.

[0068] Similarly, the second PSK2 key can be obtained in various ways: The network administrator user chooses it himself and an associated validity period DV2 is calculated using, for example, the solution of the prior art cited above; the access equipment PA creates it from a dictionary, for example, using the technique described in the French patent application published under number FR3028336, by the INPI in May 2016.

[0069] In P23, a list of STA terminal equipment registered to the RC communication network is determined. At the time of the key change, these terminal equipment may or may not be connected to the RC network.

[0070] In the following, two cases are therefore considered: In a first case, a terminal device is connected to the network RC via the access device PA, which transmits to it in P24 a reauthentication command message comprising at least the second key JK2 and a reauthentication delay DR. This delay can be configurable and chosen according to the terminal device STA, but it expires at the latest at the end of the deactivation delay DD of the first key. In P25, the access device PA receives the reauthentication request message from the terminal device.

[0071] In P26, it checks that the DR reauthentication period has not expired: If the DR reauthentication time limit has not expired, it reauthenticates the terminal equipment in P27 using the second key JK2 without extinguishing or terminating the connection; otherwise, it terminates the connection in P28.

[0072] According to a second case, a terminal device, not connected to the access device PA at the time of the key change, requests to connect. The access device PA receives at P29 a message RCNX requesting establishment of a connection comprising said first key JK1 from this terminal. At P30, it checks at least one reconnection condition CND, comprising at least the non-expiration of a predetermined reconnection time DX. This DX time generally does not expire earlier than the deactivation time DD of the first key.

[0073] If said at least one reconnection condition is satisfied: the PA equipment establishes in P31 the connection of the terminal equipment to the communication network on the basis of the first key; It triggers a procedure for re-authenticating the terminal equipment by repeating steps P24 to P28 already described in the first case. First, it transmits to it in P24 a re-authentication request message comprising at least the second key and a re-authentication delay DR. Here, this delay does not necessarily correspond to the deactivation delay of the first key PSK1 which may have already expired. On the other hand, it is chosen with a reasonable duration, generally less than the delay DD; On receipt in P25 of a re-authentication request from the terminal equipment, it checks in P26 that the delay DR has not expired, if necessary re-authenticates in P27 the terminal equipment using the second key without extinguishing the connection; Otherwise, upon expiry of the delay DR, it terminates in P28 the connection; Otherwise, if at least one CND reconnection condition is not satisfied, it rejects the connection request in P32. Examples of reconnection conditions will be detailed below in relation to the figure 5 .

[0074] Optionally, in P33, the access equipment PA notifies the terminal equipment STA of the list LST that are not connected to the RC network of the key change event and the need to reconnect within a predetermined DX reconnection time. To do this, the PA equipment transmits to them a key change notification message NCK via another communication network that it accesses via the internet network RI. For example, it sends an SMS type message to a mobile terminal capable of connecting to a mobile network RM. It should be noted that alternatively, the PA equipment, when it is equipped with a screen, can also command the display of a notification on this screen or on another screen in the house, connected to the RC network. In this way, the users of terminal equipment present in the house can become aware of the new key PSK2 or at least of the need to reconnect quickly.

[0075] In P34, the access equipment updates the LST list by removing the identifier of the STA terminal equipment that has reconnected. Optionally, in P35, it checks shortly before the expiry of the DX timeout whether the LST list is incomplete, and if not, it can extend the DX timeout by adding an additional grace period to give an additional opportunity to terminal equipments that have not yet done so to reconnect. Advantageously, it checks the status of the terminal equipments in the LST list and extends the DX timeout only for those that are trustworthy.

[0076] In relation to the figure 3 , A method for managing a connection of a terminal device STA to the communication network RC is now described according to an embodiment of the invention. This method is intended to be implemented by a device connected to or embedded in the terminal device STA.

[0077] According to a first case, it is assumed that the terminal equipment STA has previously established a connection with the RC network at T30 and that this connection is in progress when the key is changed at time t0.

[0078] At T31, it receives via this connection a CRA reauthentication command message from the access equipment PA. This message includes the second key PSK2 and a reauthentication delay DR.

[0079] Optionally, the STA equipment implements in T32 a random determination of a reauthentication time t RA included in the DR time period. It sends in T33 a reauthentication request to the PA equipment at the determined time t RA, if applicable, otherwise at the expiry of the DR time period.

[0080] In T34, once re-authenticated, the STA terminal records the new JK2 key set from the second PSK2 key.

[0081] According to a second case, the terminal equipment STA is not connected to the RC network, for example because it is out of range of this network or because it has deactivated its Wi-Fi transmission / reception module. On the other hand, it is assumed that it has connected at T35 to another communication network, for example the mobile network RM, which the access equipment PA can also access via the internet network RI. It receives at T36 a key change notification message NCK from the access equipment PA including a DX reconnection delay. At T37, when it is again within range of the RC network, it sends an RCNX connection request to the PA equipment.

[0082] At this stage, two cases are considered: either the DX timeout has expired and the access equipment PA rejects the RCNX connection request. The STA terminal receives a rejection message at T38; or the DX timeout runs out and the access equipment establishes the connection at P31. The STA terminal then receives, via this connection, a reauthentication command message, which corresponds to step T31 already described. It is followed by steps T32 to T34 already described.

[0083] In relation to the Figures 4A and 4B ,we now detail the reauthentication of a terminal equipment already registered to the communication network RC, corresponding to steps P24-P28 and T31-34. We place ourselves indifferently in one of the two cases previously described, where the terminal equipment STA is connected to the network RC at the time of the key change or requests to connect shortly after this change, under the reconnection conditions CND. In both cases, the connection has been established on the basis of the first key PSK1 and therefore of the set of keys JK1 derived from PSK1. The access equipment PA transmits in P23 a reauthentication command message CRA comprising the second key PSK2 and a reauthentication delay DR.

[0084] According to a first embodiment illustrated by the Figure 4A ,this delay corresponds to a time period during which the terminal equipment STA can choose the instant t RA at which it requests to reauthenticate itself. Advantageously, the terminal equipment STA randomly determines at T32 this instant within the indicated DR delay. This allows the access equipment PA to simultaneously transmit a reauthentication command CRA to several terminal equipment STAs comprising the same DR delay, with a guarantee that the reauthentication requests that it will have to process in return will reach it at distinct instants distributed over the DR period.

[0085] According to a second embodiment illustrated by the Figure 4B , the DR delay indicated by the access equipment to the STA terminal is an imperative delay that it has specifically chosen for this STA terminal, with the same aim of avoiding having to manage a peak of reauthentication requests.

[0086] We now consider, according to an embodiment of the invention, the second case, of a terminal device STA, registered to the RC network, but not connected at the time of the key change. It therefore has connection information including the first key PSK1 in the process of being deactivated. We detail in relation to the Figure 5 step P29 of verification of CND reconnection conditions of the STA terminal equipment by the PA access equipment.

[0087] It is assumed that the access equipment PA receives a connection request from an STA equipment based on the first key PSK1.

[0088] It is assumed that, according to the invention, the PA equipment stores a new data structure SST1 comprising status information of the first security information, for example the first set of keys JK1 from the key PSK1, intended to be used to connect terminal equipment to the RC network identified by its SSID. For example, this data structure comprises three distinct information fields relating to three distinct states or statuses that the security key can take: a field relating to a key obsolescence parameter. The PA access equipment sets this information field or parameter to the value " dprtd » for example equal to 1 for the first key as soon as it obtains a second PSK2 key and triggers the key change; a field relating to a key activity parameter. The PA access equipment positions it at « not_actvd", for example equal to 0 at the expiration of the DD deactivation period; a field relating to a DG grace period. The PA equipment sets it to 1 once the deactivation period has expired.

[0089] It is understood that the PA access equipment to the RC network manages an SST data structure per key, therefore at least an SST1 data structure for the first key and an SST2 data structure for the second key.

[0090] The SST2 data structure is initialized as follows: the field relating to a key obsolescence parameter is set to the value " non_dprtd » for example equal to 0 the field relating to an activity of the key is positioned at “ actvd ", for example equal to 1; a field relating to a grace period. The PA equipment sets it to a value " unused", for example equal to 2 as long as it is not relevant. It will be used, in accordance with the invention, when a renewal of the second set of keys JK2 from PSK2 has been decided.

[0091] It should be noted that the IEEE 802.11 standard does not provide in its current specification the possibility of associating several security information items, for example of the PSK type, with the same SSID network identifier. On the contrary, the invention proposes to introduce for a limited time period a second set of keys JK2 derived from a second key PSK2, as well as attributes making it possible to describe the current status of each of these sets of keys. These attributes are stored for example in the data structures SST1, SST2 which have just been described.

[0092] The attribute fields of these data structures therefore provide information on the status of the two key sets JK1 and JK2. These data structures are particularly useful during the coexistence period of the two key sets. For example, when the first key set has definitively expired, for example at the end of the grace period DG (or the last additional grace period DGS), the structure SST1 is erased from the memory of the access equipment PA. A new structure SST3 will be created when the second key set is renewed, at the end of its validity period DV2. Alternatively, only the attribute values ​​can be erased and the same structure SST1 is used for the key set JK3.

[0093] Upon receipt of the connection request based on the first PSK1 key from the terminal equipment STA, the access equipment PA checks in P51 the status of this first PSK1 key by consulting the SST1 data structure stored in memory. In particular, it tests the value of the obsolescence parameter. If it is set to the value " not_dpctd ", for example equal to 0, which means that the first key is not obsolete, then it triggers step P52 which corresponds to the establishment of the connection of the STA terminal equipment, followed by a re-authentication without connection extinction, as previously described in relation to the figures 2 , 4A and 4B . If on the contrary it is positioned at the value “ dpctd", for example equal to 1, it triggers step P53. Step P53 tests the second parameter of the SST1 data structure, linked to the expiration of a deactivation time of the first key. As a reminder, this time is triggered by the PA access equipment when the key is changed. If this parameter is set to the value " not_octvd ", for example equal to 0, which means that the first key is deactivated, because the DD delay has expired, then the access equipment triggers step P54. If on the contrary it is set to the value " actvd ", for example equal to 1, then the access equipment PA triggers step P52 of establishing the connection of the terminal equipment STA.

[0094] Step P54 tests the third parameter of the SST1 structure relating to the expiry of a DG grace period triggered upon expiry of the DD deactivation period. This grace period therefore extends the DX delay, i.e. the period during which a terminal device can reconnect with the first key. If this parameter is set to the value " express ", for example equal to 1, which means that the DG grace period has expired, then the access equipment triggers step P56 to reject the connection request. This means that to reconnect, the terminal equipment will have to perform an initial connection procedure to the network, as if it were not already registered. If, on the contrary, it is set to the value " not_exprd ", for example equal to 0, then the access equipment PA triggers a next step which can be step P52 of establishing a connection with the terminal STA.

[0095] Optionally, the PA equipment first triggers a step P55 for testing a status of the terminal equipment STA. Advantageously, this status is stored in memory by the access equipment PA in an SSTA data structure comprising a record associating with a unique identifier ID_STA of the terminal equipment STA a parameter IC representative of a level of confidence assigned to the terminal STA. For example, this unique identifier may be the MAC address of the terminal equipment.

[0096] It should be noted that a more secure identifier can also be obtained by exchanging between the access equipment and the terminal data “authenticating” the terminal, and therefore virtually “signed” by the terminal, which can be: Either data randomly generated at the first connection and stored by both devices; Or data actually signed using asymmetric cryptography.

[0097] This IC confidence parameter can take a first value “ trstd ", equal to 1, which means that the STA terminal equipment is trustworthy or a second value " not_trstd ", equal to 0, which on the contrary means that the STA terminal is not trustworthy. These values ​​can be assigned to the STA terminal equipment when it is first connected by a user playing the role of administrator of the RC communication network. For example, the administrator will assign the value " trstd » to the home terminal equipment, such as connected objects usually installed in the rooms of the house and to the user terminals of the residents of the house and it will affect the value « not_trstd » to a visitor terminal device.

[0098] In P55, if the parameter representing a confidence level of the STA terminal equipment is set to “ trstd", the PA equipment triggers step P52 to establish a connection to the network. Otherwise, it rejects the connection request in P56.

[0099] Thus, according to the invention, the access equipment PA filters the connection requests during a transition period which sees the two sets of security keys JK1 and JK2 coexist. The access equipment controls the duration of this transition period, which must remain as short as possible, so as not to make network management too complex. As mentioned previously, it is at least equal to the deactivation time DD of the first key PSK1. It can be extended by the duration of a grace period so as to facilitate the reconnection of terminal equipment already registered in the network, but not connected at the time the key change is triggered.

[0100] According to one embodiment, at the end of this DG grace period, the access equipment verifies that all the trusted STA terminal equipment has reconnected and then reauthenticated.

[0101] It may decide to extend the grace period by an additional grace period DGS which can be chosen less than or equal to DG, to give a last opportunity to “trustworthy” terminals to easily reconnect to the RC network.

[0102] It will be noted that according to the invention and in the case of a Wifi network, the frame management messages (for "frame management", in English), exchanged between the access equipment PA and a terminal equipment STA, are as specified by the IEEE 802.11 standard section 9.3.3.12, but that the invention proposes to specify an additional one, the reauthentication command message CRA, to invite the terminal equipment STA to reauthenticate itself, at the initiative of the access equipment PA.

[0103] For example, according to the invention, this CRA reauthentication command message comprises the following information fields: information representing a cause for re-authentication (“reason code”, in English), positioned at a value indicative of an update of the security information, for example of the PSK key (“update-PSK”, in English); the new security information, for example the new PSK key (“data”, in English); and a re-authentication DR delay, at the end of which a re-authentication request will be rejected (“max_delay”, in English).

[0104] We now present, in relation to the figure 6 , a time diagram of the exchanges between the STA1-STA4 terminal equipment and the PA access equipment of the figure 1 before, during and after a change of security keys according to one embodiment of the invention.

[0105] It is assumed that the validity period DV1 associated with the key PSK1 expires at t 0 . The access equipment PA obtains a new key PSK2 and triggers a key change as well as a deactivation delay DD of the first key PSK1.

[0106] We consider the communicating object STA1 which is connected to the network RC at the time of the key change at t0. The access equipment PA sends it a reauthentication command CRA including the new key JK2 derived from PSK2 and a reauthentication delay DR. We assume that STA1 requests to reauthenticate itself within the given delay DR. It thus obtains the new set of keys JK2 without loss of connection.

[0107] We now consider the laptop STA2, which is registered to the RC network, but is not connected at the time of the key change. We assume that it does not request to reconnect within the deactivation period DD, but that according to this exemplary embodiment of the invention, the PA equipment extends the period DD by a grace period DG during which the STA2 equipment requests to connect on the basis of the first key JK1, now deactivated. In this example, the PA equipment maintains a data structure SSTA which, as previously described, associates with a terminal equipment registered in the network information relating to a level of trust granted to it. We assume that STA2 is considered "trustworthy" (IC = "trstd" for example equal to 1).The PA equipment therefore does not reject its connection request, but asks it to reconnect according to step 42 which corresponds to the establishment of the connection of the STA terminal equipment, followed by re-authentication without extinction of connection, as previously described in relation to the . figures 2 , 3A-B.

[0108] Regarding the STA3 terminal equipment, it was not connected at the time of the key change and requests to reconnect based on the old JK1 key set after the DG grace period has expired. Although it has the "trusted" status, the access equipment rejects its connection request, which means that it must re-register to the network, like a new equipment.

[0109] The STA4 mobile terminal was not connected during the key change. It requests to reconnect during the DG grace period, but since it is not associated with the "trustworthy" status, its request is rejected by the PA access equipment.

[0110] Finally, regarding the terminal equipment STA5, it is not only "trustworthy", but also the mobile terminal of the administrator user of the RC network. Advantageously, the access equipment PA notifies the administrator of the change of keys, for example by transmitting to it an SMS (for "Short Message System" in English) type notification message via a mobile network RM or via an RC network management application installed on the terminal STA5. A first notification message is for example transmitted shortly after t0 and if at the expiry of the deactivation period DD of the first key PSK1 the terminal STA5 has still not reconnected, the access equipment PA can send it a second message before the expiry of the grace period DG.Additionally, as previously discussed, the PA equipment may also decide to extend the grace period by an additional DGS period if there are still trusted terminal equipment that have not yet reconnected to the RC network.

[0111] We now present, in relation to the figure 7 , the hardware structure of a device 100 for managing security information, security information called first security information, intended to be implemented to establish a secure connection between at least one terminal device and an access device PA to a communication network, said first security information being associated with a first validity period DV.

[0112] The device 100 further comprises a module for obtaining a second security information, capable of being implemented upon expiry of the validity period DV and a module for triggering a deactivation period for the first security information, a module for transmitting to a terminal device connected to the access device a reauthentication request message comprising at least the second security information and said deactivation period for the first security information and a module for extinguishing the connection upon expiry of the deactivation period.Advantageously, it also comprises a module for verifying at least one reconnection condition, a module for determining a list of at least one terminal device registered in the network with the “trustworthy” status prior to the triggering of the deactivation period of the first security information, and not having yet issued a connection request and a module for issuing a notification message to said at least one terminal device before the expiry of a grace period, in accordance with the embodiments described in relation to the . figures 2 , 4A , 4B , 5 And 6 .

[0113] The term "module" can correspond to a software component as well as to a hardware component or a set of hardware and software components, a software component itself corresponding to one or more computer programs or sub-programs or more generally to any element of a program capable of implementing a function or a set of functions.

[0114] More generally, such a management device 100 comprises a random access memory 103 (for example a RAM memory), a processing unit 102 equipped for example with a processor, and controlled by a computer program Pg1, representative of the module for obtaining a second security information, the module for triggering a deactivation delay for the first security information, the module for transmitting a re-authentication message and the module for extinguishing the connection, stored in a read-only memory 101 (for example a ROM memory or a hard disk). At initialization, the code instructions of the computer program are for example loaded into the random access memory 103 before being executed by the processor of the processing unit 102. The random access memory 103 contains in particular the values ​​of the first and second security information, the associated validity periods and the deactivation delay for the first security information.Advantageously, it comprises the SST1 and SST2 data structures providing information on the status of each security information, the SSTA data structures associating an identifier of a STA terminal device with a parameter representing a confidence level IC and an LST list of trustworthy STA terminal devices which have not yet reconnected to the RC network following the renewal of the first security information.

[0115] The processor of the processing unit 102 controls the obtaining of the second security information, the triggering of the deactivation delay of the first security information, the transmission of a reauthentication command message and the extinction of the connection, in accordance with the logic diagram of the figure 2 .

[0116] There figure 7illustrates only one particular way, among several possible ones, of producing the management device 100, so that it carries out the steps of the method for managing security information detailed above, in relation to the figure 2 in its various embodiments. Indeed, these steps can be carried out indifferently on a reprogrammable computing machine (a PC computer, a DSP processor or a microcontroller) executing a program comprising a sequence of instructions, or on a dedicated computing machine (for example a set of logic gates such as an FPGA or an ASIC, or any other hardware module).

[0117] In the case where the device 100 is produced with a reprogrammable computing machine, the corresponding program (i.e. the sequence of instructions) may be stored in a removable storage medium (such as for example a floppy disk, a CD-ROM or a DVD-ROM) or not, this storage medium being partially or totally readable by a computer or a processor.

[0118] The different embodiments have been described above in relation to a management device 100 integrated into a residential gateway but it can more generally be embedded in any PA access equipment to a local communication network.

[0119] Finally, we present, in relation to the figure 8 ,the hardware structure of a device 200 for managing a connection of a terminal device to a communication network, comprising equipment for accessing said network, said connection being secured by first security information.

[0120] The device 200 comprises a module for receiving from said access equipment via a connection to the communication network a reauthentication command message, comprising at least a second security information and a reauthentication delay, capable of being implemented when the terminal equipment is connected to said network, a module for transmitting, within the reauthentication delay, a reauthentication request message to said access equipment comprising the second security information, and a module for recording in a memory the second security information in place of the first security information.Advantageously, it also comprises a module for receiving a security information change notification message via an interface with another communication network, said message comprising a reconnection time to said network, a module for sending a reconnection request message to the communication network (RC) within said time and a module for randomly determining a time for sending said reauthentication request message to said access equipment within the reauthentication time in accordance with the various embodiments described in relation to the . figures 3 , 4A , 4B And 6 .

[0121] The term "module" can correspond to a software component as well as to a hardware component or a set of hardware and software components, a software component itself corresponding to one or more computer programs or sub-programs or more generally to any element of a program capable of implementing a function or a set of functions.

[0122] More generally, such a device 200 comprises a random access memory 203 (for example a RAM memory), a processing unit 202 equipped for example with a processor, and controlled by a computer program Pg2, representative of the reception module, the transmission module and the recording module, stored in a read-only memory 201 (for example a ROM memory or a hard disk). At initialization, the code instructions of the computer program are for example loaded into the random access memory 203 before being executed by the processor of the processing unit 202. The random access memory 203 contains in particular the first and second security information and the reauthentication time. The processor of the processing unit 202 controls the reception of the reauthentication command message, the transmission of a reauthentication request message and the recording in memory of the second security information in place of the first, in accordance with the logic diagram of the 。 figure 3 .

[0123] There figure 8 illustrates only one particular way, among several possible ones, of implementing the management device 200, so that it carries out the steps of the method for managing a connection detailed above, in relation to the figure 3 . Indeed, these steps can be carried out indifferently on a reprogrammable computing machine (a PC computer, a DSP processor or a microcontroller) executing a program comprising a sequence of instructions, or on a dedicated computing machine (for example a set of logic gates such as an FPGA or an ASIC, or any other hardware module).

[0124] In the case where the access equipment is produced with a reprogrammable computing machine, the corresponding program (i.e. the sequence of instructions) may be stored in a removable storage medium (such as for example a floppy disk, a CD-ROM or a DVD-ROM) or not, this storage medium being partially or totally readable by a computer or a processor.

[0125] The different embodiments have been described above in relation to a management device 200 integrated into a terminal device STA, but it can also be independent of this terminal device and connected to it.

Claims

1. Method for managing security information, referred to as first security information (PSK1, JK1), intended to be implemented in order to establish a secure connection between at least one terminal equipment (STA) and an access equipment (PA) for accessing a communication network (RC), said first security information (PSK1, JK1) being associated with a validity period (DV1), characterized in that said method is implemented by said access equipment and in that it comprises: - upon expiry of the validity period (DV1), obtaining (P21) second security information (PSK2, JK2) and triggering (P22) a deactivation deadline (DD) for the first security information (PSK1, JK1); - if a said terminal equipment is connected to the access equipment, transmitting (P24), to said terminal equipment, a reauthentication command message (CRA) comprising at least the second security information and a reauthentication deadline (DR), said reauthentication deadline expiring at the latest at the end of said deactivation deadline for the first security information; and - if a reauthentication request message (RRA) is received (P25) from the terminal equipment before the expiry of the reauthentication deadline, reauthenticating (P27) the terminal equipment using the second security information without terminating the connection.

2. Method for managing security information according to Claim 1, characterized in that, following the triggering of the deactivation deadline (DD), upon receipt of a message (RCNX) requesting establishment of a connection from a terminal equipment (STA) comprising said first security information (PSK1, JK1), the method comprises checking (P26) at least one reconnection condition (CND), said at least one condition comprising at least the non-expiry of a predetermined reconnection deadline (DX), said reconnection deadline expiring at the earliest at the end of the deactivation deadline for the first security information, and if said at least one reconnection condition is satisfied: - establishing (P31) the connection of the terminal equipment on the basis of the first security information (PSK1, JK1); - transmitting (P24), to said terminal equipment, a reauthentication request message (CRA) comprising at least the second security information (PSK2, JK2) and a reauthentication deadline (DR); and - terminating (P28) the connection upon expiry of the reauthentication deadline.

3. Method for managing security information according to Claim 2, characterized in that the reconnection deadline (DX) expires at the end of the deactivation deadline (DD) for the first security information (PSK1, JK1).

4. Method for managing security information according to Claim 2, characterized in that the reconnection deadline (DX) expires at the end of a grace period (DG) triggered upon expiry of the deactivation deadline (DD) for the first security information.

5. Method for managing security information according to Claim 4, characterized in that, with said terminal equipment (STA) having been previously registered in the network (RC) in association with trust information (IC), said step of checking at least one reconnection condition (CND) furthermore checks that the trust information is set to a value "trusted".

6. Method for managing security information according to Claim 5, characterized in that it comprises determining (P23) a list (LST) of at least one terminal equipment registered in the network with the trust information set to the value "trusted" prior to triggering the deactivation deadline for the first security information and having not yet transmitted a connection request, and transmitting (P33) a notification message to said at least one terminal equipment before the expiry of the grace period.

7. Method for managing security information according to Claim 6, characterized in that, upon expiry of the grace period, an additional grace period (DGS) is triggered as long as the list (LST) is not empty.

8. Device (100) for managing security information, referred to as first security information (JK1), intended to be implemented in order to establish a secure connection between at least one terminal equipment (STA) and an access equipment (PA) for accessing a communication network (RC), said first security information being associated with a first validity period (DV), characterized in that it is configured: - upon expiry of the first validity period, to obtain second security information (JK2) and trigger a deactivation deadline (DD) for the first security information; - if a said terminal equipment (STA) is connected to the access equipment, to transmit, to said terminal equipment, a reauthentication request message (CRA) comprising at least the second security information (PSK2, JK2) and a reauthentication deadline (DR), said reauthentication deadline expiring at the latest at the end of said deactivation deadline (DD) for the first security information; and - if a reauthentication request message (RRA) is received from the terminal equipment before the expiry of the reauthentication deadline, to reauthenticate (P27) the terminal equipment using the second security information without terminating the connection.

9. Access equipment (PA) for accessing a communication network (RC), characterized in that it comprises a device (100) for managing security information according to Claim 8.

10. Method for managing a connection of a terminal equipment (STA) to a communication network (RC), comprising an access equipment (PA) for accessing said network, said connection being secured by first security information (PSK1, JK1), said method being implemented by said terminal equipment and comprising: - when it is connected to said network, receiving (T31), from said access equipment and via a connection to the communication network, a reauthentication command message (CRA) comprising at least one second item of security information (PSK2, JK2) and a reauthentication deadline (DR) shorter than or equal to a deactivation deadline (DD) for the first security information, and - transmitting (T33), within the reauthentication deadline (DR), a reauthentication request message (RRA) to said access equipment comprising the second security information (JK2), and recording (T34) the second security information (PSK2, JK2) in place of the first security information.

11. Method for managing a connection of a terminal equipment according to Claim 10, characterized in that it comprises: - when it is not connected to said network, receiving (T36) a message (NCK) notifying a change of security information via an interface with another communication network, said message comprising a reconnection deadline (DX) for reconnecting to said network, said deadline expiring at the earliest at the end of the deactivation deadline (DD) for the first security information (PSK1, JK1), and - transmitting (T37) a reconnection request message to reconnect to the communication network (RC) within said deadline (DX).

12. Method for managing a connection of a terminal equipment according to either of Claims 10 and 11, characterized in that it furthermore comprises determining (T32) a time of transmission of said reauthentication request message (RRA) to said access equipment within the reauthentication deadline (DR).

13. Device (200) for managing a connection of a terminal equipment (STA) to a communication network (RC), comprising an access equipment (PA) for accessing said network, said connection being secured by first security information (PSK1, JK1), characterized in that said device is configured: - to receive a reauthentication command message (CRA) from the access equipment via a connection to said network, said message comprising at least one second item of security information and a reauthentication deadline (DR), said deadline expiring at the earliest at the end of the deactivation deadline (DD) for the first security information (PSK1, JK1); and - to transmit, within the reauthentication deadline, a reauthentication request message (RRA) to said access equipment comprising the second security information (PSK2, JK2).

14. Terminal equipment (STA) able to be connected to a communication network (RC) by an access equipment (PA) for accessing said network, characterized in that it comprises a device (200) for managing a connection according to Claim 13.

15. Computer program product comprising program code instructions for implementing a method according to any one of Claims 1 to 7 and 10 to 12 when it is executed by a processor.