EP2002636A1

EP2002636A1 - Loss of control of connection between a first device and a second device, access point and corresponding user terminal in shared network

Info

Publication number: EP2002636A1
Application number: EP07731718A
Authority: EP
Inventors: Matthieu Malledant; Patrick Langlet; Matthieu Maupetit
Original assignee: France Telecom SA
Current assignee: Orange SA
Priority date: 2006-04-04
Filing date: 2007-03-09
Publication date: 2008-12-17
Also published as: WO2007113408A1

Abstract

The invention concerns method for loss of connection between a first device and a second device (D1, D2) which consists in executing (A) an initializing command on the first device (D1), initiating (B) a process of identification from a first identification value (SSID) of said first device (D1), initiating (C) a local initializing command on the second device (D2) during a common initializing step, establishing (D) a common session key (CSK), encrypting (E) in the first device (D1) a second identification value (ssid) and a secret key value (Ks1) of the first device (D1) based on an encrypted value (VssidKs1) transmitted to the second device (D2), decrypting (F) the encrypted value (VssidKs1) using the common session key (CSK) and configuring the second device (D2) based on the second identification value (ssid) and the secret key (Ks1) of the first device for connecting an pairing with the first device (D1).

Description

METHOD FOR CONTROLLING THE CONNECTION OF A FIRST AND

SECOND DEVICE, ACCESS POINT AND USER TERMINAL IN CORRESPONDING SHARED NETWORK.

The invention relates to a method for controlling the connection of a first and a second device, an access point and a shared network user terminal, in particular a WiFi network, forming a server device or a client terminal respectively.

At the present time, Wi-Fi shared network communication interfaces are defined by 802.11 (b), (g), (i) and (e) and rely on authentication and data encryption protocols for security and access control such as its protocols WPA - PSK and WPA2 - PSK for "Wifi Protection Access" in English.

More specifically, these protocols apply to access points and user terminals requesting a wireless connection to them, via a radio link.

To provide such a new connection to this type of access point, it is necessary for the user terminal user to manually enter a hexadecimal key value at the user terminal.

Although this procedure is relatively easy to implement on a terminal of the PC type, nomadic personal computer for example, the following difficulties could be highlighted:

- the hexadecimal value of the key is not well understood by the users, with a risk of confusion of the literal value O (letter O) and 0 (digit 0);

the introduction of a key comprising 26 successive characters is difficult to memorize, whereas the direct copy introduces a significant risk of errors;

- the position of the key on the access point introduces a difficulty extra to read the key;

- i! In addition, it is necessary to know the configuration of the access point in order to retain the same configuration of security and access control, among WEP Open Open or Anonymous Wired Equivalent Privacy protocols, WEP Shared for "Wired Equivalent Privacy" "Shared in English or WPA - PSK already cited.

When the user terminal is a termina! with limited resources, such as PDA for "Personal Digital Assistant" (English personal digital assistant) comprising for example only a screen and a small keyboard, the difficulty of entering 26 hexadecimal characters is further increased.

When, finally, the user terminal, more rudimentary, has no screen and / or keyboard, the task is even more difficult and it is then necessary to install such a device on a host computer and configure all for connection to an access point.

Among the solutions of the prior art known to the inventors, mention may also be made of the one described in the French patent application FR05 05315 filed on May 26, 2005 in the name of the applicant incorporated by reference.

The solution proposed in this document, applicable to an access point and a shared network user terminal is to perform a local initialization command for a certain duration on the access point and the user terminal, and to a temporary pairing of the access point and the user terminal, to exchange the respective initialization duration values of the access points of the user terminal. If the respective initialization durations of the latter differ from a value lower than a threshold value, the connection is continued. Otherwise, the connection is inhibited.

Such a process is satisfactory. However, it may happen that a careless user exceeds the relative initialization time of the access point and the user terminal, which makes the connection process not easy to perform in this case. The adoption of Threshold value too high reduces the selectivity of the process.

The present invention aims to overcome the disadvantages and limitations of known prior art.

In particular, an object of the present invention is the implementation of a method of controlling the connection of a first and a second device, such as an access point and a shared network user terminal, WiFi type, in which the tedious introduction and error source of a key value in hexadecimal notation is suppressed.

Another object of the present invention is in particular the implementation of a method for controlling the connection of an access point and a shared network user terminal, of the WiFi ₁ type, in which the transmission of any Cryptographic or wireless value is provided by radio between the access point and the user terminal.

Another object of the present invention is also the implementation of a method for controlling the connection of a first and a second device, such as an access point and a shared network user terminal, of WiFi type, in which the difference of initialization time duration on the access point respectively on the shared network terminal is made substantially inoperative, through the introduction of an authentication and access control process by exchange of encrypted values over the air.

The method for controlling the connection of a first and a second device provided with cryptographic resources, which is the subject of the invention, is remarkable in that it consists at least in executing a local control of initialization during a certain period of time. duration on the first device, and during this time, initiate an identification process on the first device from a first identification value of the first device, execute before the end of this initialization a local initialization command on the second device for temporarily placing the second device and the identification process through the first device, the initialization of the first and second devices being performed according to a common initialization step. During the common initialization step, the method further comprises establishing a common session key to the first and second devices, to encrypt, in the first device, a second local identification value of the first device and a value secret key associated with this first device by means of said common session key according to an encrypted value and transmit this encrypted value from the first to the second device, and, at the latter, decrypt the encrypted value of the second identification value and the secret key value associated with the first device using the common session key, and configure the second device from the second local identification value and the secret key value for pairing connection with the device. first device.

According to another aspect, the method which is the subject of the invention is remarkable in that it furthermore comprises the transmission by the second device of a public key to ensure the transmission of the common session key in the form of the encrypted value of the first at the second device, the decryption of this encrypted value of the common session key by this second device to restore to the latter the common session key.

This makes it possible to avoid the prior establishment and / or the sole initiative of the second device of the joint session session.

The method which is the subject of the invention is furthermore remarkable in that the first device being a shared network access point forming a server device, this server device executes, following the execution of the local initialization command, by actuating a trigger button and the launching step of an identification process by opening the pairing process from the first identification value, an event waiting stage, these events comprising at least either the transmission of a request for establishment of common session key, or the transmission of a request for reception of pairing data by the second device or the expiration of a pairing delay, and, an end step of the pairing process called either on expiration of the pairing delay or on detection of a number of common session key establishment request greater than unity.

The method which is the subject of the invention is furthermore remarkable in that the step of processing any common session key establishment request includes at least the control of the reception of a number of key establishment requests. common session superior to the unit.

The method which is the subject of the invention is furthermore remarkable in that waiting for the transmission of a request for reception of pairing data by the second device is formed by a loop back to the waiting step of The event is conditional upon the expiration of the pairing delay and the failure to receive a common session key establishment request and includes a step of processing any pairing data request.

The method that is the subject of the invention is furthermore remarkable in that for a number of session key establishment requests greater than unity, the step of processing any request for receiving pairing data includes at least one the transmission, by the server device, of an error message and the call of the end of pairing step.

The method which is the subject of the invention is furthermore remarkable in that the second device being a shared network terminal, this method includes at least one step of inviting the terminal user to execute the local initialization command. on the first device, forming an access point to this shared network, a paired shared network search scanning step, and, upon detection of a server device constituting an access point, a control step of temporary connection of the client terminal to this access point, and, upon successful provisional connection, a transmission control and joint session key establishment request step, and, upon receipt of an acknowledgment of receipt of the request common session key set-up, a polling pairing request data transmission check step, and, upon receiving pairing data, a config control step pairing and connection management of the client terminal to the device server constituting an access point.

The method which is the subject of the invention is furthermore remarkable in that, on the client terminal side, in the absence of detection of a server device constituting an access point, it comprises a step of returning to the invitation stage of the user of this client terminal conditional on a choice by this user is the repetition of the execution of the local initialization command, or the execution of a conventional connection.

The method which is the subject of the invention is furthermore remarkable in that, on the client terminal side, on detecting a plurality of server devices constituting a shared network access point, this method comprises another step of returning to the step inviting the user of this client terminal conditional on a timed choice by using either the repetition of the execution of the local initialization command, or the execution of a conventional connection.

The shared network access point forming a server device, object of the invention, is remarkable in that it comprises at least local initialization control means by actuating a trigger button, launching means an identification process by opening the pairing process from a first identification value, means for executing an event waiting stage, these events comprising at least one transmission of a common session key establishment request, ie the transmission of a request for reception of pairing data by a shared network client terminal or the expiry of a pairing delay, closure means of the pairing process ordered either on expiration of the pairing delay or on detection of a number of session key establishment requests greater than unity.

The shared network client terminal object of the invention is remarkable in that it includes at least means for displaying an invitation message from the user of this client terminal to execute a local initialization command on a shared network access point, forming a server device, means for searching for shared network pairing and temporary connection means of this client terminal to this access point, transmission control means of a common session key establishment request, transmission control means of a polling pairing data request and pairing configuration and connection control means of the client terminal to the server device forming this access point.

The method of controlling the connection of a first and a second device, the access point and the shared network user terminal, objects of the invention, find application to the connection of WiFi terminals to the access terminals. to the INTERNET network, in particular to user terminals of any type, in particular to home peripherals equipped with WiFi, Bluetooth, power line or other line interfaces. they will be better understood by reading the description and by observing the following drawings in which:

FIG. 1a represents, by way of illustration, a general flowchart of the essential steps of the method of controlling the connection of a first and a second device according to the subject of the present invention;

FIG. 1b represents an implementation detail of the step of establishing a common session key in a nonlimiting preferential implementation mode when the first and the second device comprise a radio link, such that a WiFi connection for example;

FIG. 2a represents, by way of illustration, a nonlimiting preferred mode of implementation of the method that is the subject of the invention by the first device, when the latter forming a shared network access point constitutes a server device;

FIG. 2b represents, as an illustrative example, a nonlimiting preferential embodiment of the method that is the subject of the invention by the second device, when the latter constitutes a client user terminal;

FIG. 3 represents, by way of illustration, a block diagram of a shared network access point forming a server device allowing the implementation of the method of the invention as shown in Figure 2a.

A more detailed description of the method for controlling the connection of a first and a second device, in accordance with the subject of the present invention, will now be given in connection with FIG. 1a and the following figures.

In general, it is indicated that the first and second devices are provided with cryptographic resources and capable of executing encryption operations - decryption for example.

With reference to FIG. 1a, it is indicated that the method which is the subject of the invention consists in executing A local initialization command, denoted L! Di for a certain duration on the first device noted Di and during this period, to start an identification process in step B on this first device D- _t , the identification process being carried out from a first value identification of this first device and noted ID (SSiD).

Step B is then followed by a step C consisting in executing, before the end of the initialization executed in step A, a local initialization command on the second device D ₂ , this step in step C being noted LI D ₂ , to put in temporary communication the second device and the identification process via the first device Di.

Thus, it is understood that the initialization of the first device Di and the second device D ₂ are performed according to a common initialization step, concomitantly or not.

In particular, it is noted that the effective difference in the initialization duration of the first and second devices is then substantially ineffective, unlike the prior art previously described in the description.

Step C is then followed by a step D of establishing a session key, denoted CSK, common to the first device Di and the second device D ₂ .

The concept of establishing a common session key covers both the establishment and the common storage of the same key of session by a secret convention for example, or, where appropriate, restoration of a common session key by the first device D ₁ for example, and the communication in encrypted form of this common session key to the second device D ₂ and it will be described later in the description.

Step D is then followed by a step E of encrypting in the first device Di a second local identification value of this first device, denoted ssid, and a secret key value denoted K _s i associated with the first device Dt , the corresponding encryption being effected by means of the common session key CSK. An encrypted value is thus obtained, which is then transmitted from the first device D ₁ to the second device D ₂ .

The corresponding operation in step E of FIG. 1a is noted by the symbolic relation:

C _csκ (ssid, Ks1) → V _sslιiKsl .

Step E is then followed by a step F of decrypting the previous encrypted value transmitted V _ssldKsX , this transmitted encrypted value being representative of the second local identification value ssid and the value of the associated secret key K _s i at the first device. It is decrypted using the common session key CSK which of course has the second device D ₂ .

In step F _1, the decryption operation is noted symbolically:

Step F is then followed by a step G consisting in configuring the second device D ₂ from the second local identification value ssid and the secret key value K _s i for connection by pairing with the first device Di .

In general, it is indicated that the method which is the subject of the invention advantageously comprises the transmission by the second device D ₂ to the first device Di of a public key K _pu2 associated with the second device D ₂ to ensure the transmission of the key CSK session common in the form of encrypted value from the first to the second device.

In this case, the decryption of the encrypted value and the session key CSK by the second device D2 is intended to restore the second device common session key CSK,

The above operations are shown in Figure 1b wherein the step D1 ₀ denotes a generation of the common session key step CSK, which may advantageously consist in generating this key as a sequence of random bits, for example. The number of bits chosen may be 64 or 128 bits, for example, without limitation.

Step D10 is then followed by a step of transmitting the public key represented by the relation:

D ₂ ^Kp ' ^Λ > D ₁ .

At the first device, the common session key CSK is encrypted and transmitted to the second device in encrypted form according to the symbolic relationship shown in FIG. 1b:

D ₁ ^C ^ ^iCSK) > D ₂

The decryption operation is then executed at the second device in step D ₁₃ to restore the common session key CSK this decryption operation being represented by the relation:

In the preceding symbolic relation, it is indicated that K _p a designates the private key associated with the second device D ₂ and in particular the public key K _pU2 associated with the latter.

A more detailed description of the connection control method of a first and a second device, according to the subject of the present invention, will now be given in the particular application in which the first device is an access point. AP to a shared network, that is to say a WiFi network for example, and where the second device D ₂ is a WiFi terminal seeking to connect to the access point AP considered. In addition, the AP AP constitutes a server device and the terminai seeking to connect to the aforementioned access point is a user terminal UT user.

The operating mode and the behavior of the server device allowing the implementation of the method which is the subject of the invention will now be described in connection with FIG. 2a.

The operating mode of the server device represented in FIG. 2a is represented after step A of FIG. 1a, that is to say the local initialization step of the first device D1, in other words of the AP access point forming the server device, has been executed.

This step may advantageously be performed by actuating a trigger button which makes it possible to execute the local initialization command previously mentioned.

Following the execution of this local initialization command, the step of launching an identification process by opening the pairing process from the first identification value, identification process noted ID (SSID ) is performed in step 101, which corresponds to step B of Figure 1a at the corresponding server device.

The aforementioned step 101 is then followed by an event waiting step 102, the server device waiting for events comprising at least one transmission of a common session key establishment request, this operation being noted R_CSK?, or the transmission of a request for reception of pairing data by the second device forming the termina! UT user, this event being noted R_UT_G_D?, or the expiration of a pairing time noted P_D_ε?.

In FIG. 2a, the steps 102a, 102b and 102c represented by a dashed rectangle correspond in fact to the realization of a corresponding event of the event waiting step 102.

Thus, the transmission of a request for the establishment of a common session code, denoted 3 R_CSK in step 102a, results from the execution of such a transmission and a positive response to the corresponding test executed in step 102. The same is true for step 102b when performing the transmission of a pairing data reception request, by the second device, this operation being noted, 3 R_UT_G_D.

Finally, in step 102c, the pairing time PJDJE has expired, which makes it possible to go to an end of pairing step 105 called, either on expiration of the pairing delay considered, or on detection of a number of common session die establishment requests greater than the unit, as will be described later in the description.

As shown in FIG. 2a, the waiting time for the second device to transmit a request for establishing a common session code R_CSK is formed by a feedback loop at step d. event waiter 102 including a step of processing any session key setup request, noted 103 in FIG. 2a.

The step 103 of processing any session key establishment request is represented in the form of a test due to the execution during the aforementioned step 103 of a series of tests which will be explained below.

Similarly, waiting for the transmission of a request for reception of pairing data by the second device D ₂ , that is to say, the receipt of the request R_UT_G_D by the first device Di forming the point AP access, is formed by a loop back to the event waiting step 102 conditional on the non-expiration of the pairing delay, P_DJE <1, and the absence of receipt of a request d common session key establishment ^ R-CSK. This return loop further includes a processing step 104 of any request for receiving pairing data R_UT_G_D.

Thus, the return loop represented in FIG. 2a for executing waiting for the transmission of a request for reception of pairing data by the second device, comprises the execution of the condition of step 102 of FIG. waiting for existence events of a request receiving the pairing data Ξ RJJT GJD in step 102b and the processing step 104 of this request by the server device and checking the conditions 104a of non-expiration of the pairing delay, this condition being noted PJDJE <1, and of not receiving a request for establishment of common session key noted: ^ R_CSK and the verification of pairing data transmitted to the user terminal UT. This condition being denoted PD ≠ 0.

Finally, as shown in FIG. 2a, the step of processing any session key establishment request 103 also includes the control of the reception of a number of common session key establishment requests greater than one. 'unit.

In this case, the number of NRjDSK common session key establishment requests is counted and on exceeding a number greater than 1 during the pairing time P_DJΞ, this condition being verified in step 104 of FIG. 2a. and represented in step 104b according to NR_CSK> 1, the step of processing any said pairing data reception request 104 includes transmitting, by the server device, an error message and the call of the end of pairing step 105 above.

Various indications for implementing the operating mode of the server device constituting an access point AP making it possible to implement the method that is the subject of the invention, as represented in FIG. 2a, will be given hereinafter.

Identification step 101

In step 101, that is to say after the user has, for example, pressed the trigger button of the access point AP, three events are executed:

a light flashes on the access point AP forming the server device during the entire pairing period.

the server device forming the access point AP then switches according to the standard pairing mode on the basis of its main identifier. to say its MAC address. In this phase, the access control is deactivated and any WiFi-type UT user terminal that successfully connects to the AP access point by a WiFt type link is then added as a candidate user terminal for the MAC address considered.

During this first period, the main identifier is then broadcast by the access point by the radio interface of the latter.

The standard pairing mode thus lasts for a determined time δ ₀ which can be of the order of 600 seconds for example. However, in the case where this delay expires, the temporary connection procedure based on the MAC address is then reactivated.

A new local identifier playing the role of first local identifier noted SSlD or pairing identifier is then created. This local identifier has no WiFi security measures ie no WEP or WPA security protocol and then provides access to a LAN separate and distinct from the original LAN.

This separate LAN does not allow access to the Internet and is totally isolated from the original LAN.

This separate local area network may have, advantageously but without limitation, the following characteristics:

the IP range of the local network is given by a domain IP address and an IP network mask;

a DHCP server for "Dynamic Host Configuration Protocol" in English makes it possible to deliver IP addresses to client terminals UT from an address range between a start address and an end address;

a firewall system only allows DHCP or HTTP requests between a UT client user terminal and the AP access point, no WtFi traffic being authorized between the client user terminal;

an HTTP server having two URLs makes it possible to process the R_CSK or R_UT_G_D common session key transmission requests during the event waiting step. as described previously in the description. The corresponding WEB server does not have other access pages;

the pairing identifier SSiD is valid during a time S 1 for opening the pairing process which is valid for about 60 seconds. When this time has expired, the first local SSID pairing ID is disabled.

In addition, pressing the trigger button of the AP AP constituting the server device, while this server device is in the mode of drawing that is to say, pending events 102, a the effect of restarting and setting all deadlines to zero, and the corresponding state machine and the pairing process start over again.

Step 103 of the processing of a common session key transmission request R CSK.

The aforementioned step 103 executes the responses to the request for sending common session key launched by the user terminal UT during the common initialization period.

The aforementioned processing is performed as a resolution of the conditional constraints below:

if the server device acting as AP access point is in WEP security mode or, if necessary, has no security mode, the server device returns a code 200 HTTP message and an HTML page containing only a specific string indicating, for example, that the pairing process is now complete, in coded form Result = 4 \ n;

- if a time ^ ₂ request pairing taken for example equal to 30 seconds has expired, then an HTTP server device returns a message code 200, and an HTML page containing only a character string encoded form Result = 3 \ not ;

if the server device forming AP access point has already received a public key to perform the transmission of the joint session cie as described previously in the description, via the public access server, then, the server device playing the role of an AP access point returns a code HTTP message 200 and an HTML page containing only a string of characters. invitation in coded form Result = 2 \ n;

- The server device then tries to read the public key Kp _u2 and if an error is detected, the server device returns a 200 code HTTP message and an HTML page containing a string of characters coded Result \ n;

if the server device loads the public key K _pu2 then it proceeds to return an HTTP message 200 and an HTML page containing a result in coded form Resuit = 0 \ n.

Step 104 of processing a request for transmission of pairing data by the user terminal UT request UT G D.

The processing step 104 executes the responses of the server device to the aforementioned requests transmitted by the user terminal UT.

The processing step 104 is executed as a verification of the successive conditional constraints:

if the server device has not received a request for transmission of CSK session code or has not received a public key for transmission of such a session key, then it returns an HTTP message code 200 and an HTML page. containing only the coded result Resuit = 3 \ n;

if the AP access point has received more than one session key transmission request or more than one public key K _pu2 , then it returns a code 200 HTTP message and an HTML page containing only the coded result Resuit = 2 not.

This condition is represented in step 104b of FIG. 2a. The pairing process of the server device is then terminated by calling the end pairing step 105 which has the effect of deactivating the first local identifier value SSlD. The pairing process can be restarted by pressing the pairing trigger button again On the server device playing AP role AP.

if the pairing request time S ₂ has not yet expired then the server device returns a code 200 HTTP message and an HTML page containing only the coded result Resuit = 1 \ n;

if, on the other hand, the pairing request delay δ ₂ has expired and if the server device acting as the AP access point has received only a session key transmission request or request, then i! returns an HTTP message code 200 and a page containing the information shown below in Table 1.

Table 1:

Resuit = 0 / n

EKeyi EKey1 \ n

EKey2 EKey2 \ n

EKey3 EKey3 \ n

EtV EIWi

EPSK EPSKVn

ESSID ESSID \ n

The result is the result Result = 0 \ n accompanied by certain values in which:

EKeyi, EKey2, EKey3, EiV, EPSK and ESSID are the respective encrypted values of the session key or, more exactly, a combination of a session key value and a public key value such as the key K _pU2. associated with the user terminal UT, and where ESSiD designates the value encrypted by a symmetric encryption protocol type DES, for example, the second local identification value of the server device.

Step 105, end of pairing step.

When the opening time of the trusted pairing process is exceeded, the trusted pairing process is terminated.

Any pending HTTP requests are answered but no new HTTP requests are accepted. When all requests HTTP has been processed or the delay δ \ has been reached, the pairing ID is disabled. The pairing process is not stopped yet and continues until its own pairing time, the standard pairing time S 0, has expired.

A more detailed description of the operating mode of the client terminal for the implementation of the method which is the subject of the invention will now be given in connection with FIG. 2b, when this client terminal UT is in relation with the operating server device as represented in FIG. 2a.

First, the client terminal UT displays a step of inviting the user of the client terminal on a screen, such as the screen of a PDA or any device with a screen by for example, to execute the local initialization command on the first device, that is to say the server device playing the role of access point AP in shared network. This operation is represented in step 201 in FIG. 2b.

Step 201 is followed by a step 202 of searching for a paired shared network search, ie searching for the identifier of the access point AP constituted by the MAC address of the latter.

On negative response at step 202 that is to say when no access point and in particular no access point MAC address is detected, as represented in step 202a of FIG. 2b, a return is made to the invitation step 201 via a choice step 208 offered to the user between a standard connection 208a or on the contrary a return to the invitation step 201 to make a connection Trusted.

The choice step 208 is in fact a step back to the user terminal conditional user's invitation stage of choice by this user, either from the repetition of the execution of the local command 201 or from the execution of a conventional connection 208a.

On a positive but detrimental response, in step 202 of detecting an AP access points number greater than the unit represented in step 202b of FIG. 2b, this situation being represented by the detection of n nAP access point then, the method object of the invention as shown FIG. 2b comprises another step of returning to the step of inviting the user of the client terminal 201 conditional on a timed choice 207 by the user of either the execution of the local command or the execution of the a conventional connection 207a.

The detection of a plurality of AP access points can result, for example, from the existence, in an apartment building, of neighboring access points which simultaneously transmit their MAC address, the user terminal then detecting several points of access. AP access on which he does not have to connect.

When, on the other hand, only one AP access point has been detected acting as a server device, as represented in step 202c of FIG. 2b, then a temporary connection control step of the client terminal UT at the point d said AP access is called at step 203.

The aforementioned temporary connection is made initially on the basis of the MAC address of the access point AP and then on the basis of the first local identification value of the server device, the value SSID previously described in the description.

On a negative response at step 203, an error message at step 203a is sent and a return to step 201 is performed through the choice step 208 and alternative choice 208a previously described in the description.

In contrast, on positive response at step 203, the provisional connection being successful, a transmission control step of a common session key establishment request 204 represented by the relation R_CSK? in Figure 2b is executed.

On a negative response in step 204, a step 204a of transmitting an error message due to the existence of a common session key allows the return to step 201 via the step choice 208 and standard connection choice 208a.

On the contrary, on a positive response in step 204, a polling pairing request request transmission step 205 is executed by the user terminal UT which, in the operation polling still referred to as "Polling" in English, search the encrypted value VssidKsl previously mentioned in the description.

On negative answer to the test 205, and for a number of common session keys N CSK> 1 or for a number of public states associated with a user terminal greater than 1, a step of returning to the invitation step 201 by the The intermediate of the selection step 208 of the standard connection 208a is further executed.

On the contrary, on a positive response at step 205, a step 206 of configuration control of pairing and connection of the client terminal to the server device constituting an access point, is executed.

In particular, the step 206 makes it possible, thanks to the decryption G represented in FIG. 1a, to restore the identifier values, the second local value of identifier ssid, and the secret key K _s i associated with the server device, acting as a point d AP access.

On negative response to the test 206, that is to say on decryption error for example, a return to the invitation step 201 is performed via the selection step 208 and the standard connection 208a. On the contrary, on a positive response in step 206, a step 206b is called the execution of the queuing process between the user terminal UT and the server device on the basis of the pairing parameters and in particular the values obtained by decryption at step 206.

The pairing data correspond to those contained in Table 1 previously described in the description.

Various implementation details of the method of the invention as shown in FIG. 2b will now be given below:

When the user UT client tries to connect to the pairing identifier of the server device that is to say the first local identification value issued by the latter SSID ₁ this operation is performed by successive requests executed every 5 seconds for example. This procedure does not correspond to that of a passive discovery such as obtaining the MAC address of the server device because the first locai identifier of the SSID server device, unlike the MAC address, should not be broadcast. With regard to the choice timed in step 207 on detecting a plurality of access points nAP, it is indicated that this delayed choice of the order of one minute, allows the return to the invitation step 201.

step 203 at the AP access point:

During this step the temporary connection to the AP access point allows the user terminal AP to obtain an IP address seion the DHCP protocol already mentioned.

step 204:

During this step the client terminal UT transmits its common session key transmission request CSK and public key transmission K _pU 2 for example in the form of an HTTP POST message to the server device forming the access point AP .

These requests are transmitted to the URL address previously mentioned in the description and the key values are indicated in encrypted form in the parameter P of the transmitted HTTP POST request.

step 205 of scanning:

When I finished it! UT user successfully transmitted his public key to the server device, he then enters a polling mode in English with a period of five seconds for example until he receives a response.

step 206:

When the user terminal receives pairing data by a response made by the transmission URL of the response data via the pairing data transmission URL server, and when the coded value of the result is Result = Q as described previously in the description, it then receives the pairing data indicated previously in Table 1 in the description, and, after decryption of these values, it has the second local identification value of the server device ssid and some private key K _s i associated with the server device.

Finally, it is understood from the observation of FIG. 2b that on the absence of detection of a server device located in access point AP ₁ on unsuccessful provisional connection, on the existence of a session key already received or expiration of the delay of pairing, on receipt of an error message of the first device for receiving a number of requests for setting a common session key greater than unity or for failure of the configuration control step of the termina! client and connection to the server device, the method allows return by the feedback loop to the client terminal user invitation step, step 201 of Figure 2b.

The invention furthermore covers a shared network user terminal connection device forming an access point to this shared network, and operating as a server device vis-à-vis client terminals.

Such a server device is now described in conjunction with FIG. 3. In general, such a server device comprises, for a WiFi type shared network for example, a module 1 Q WiFi radio link signal interface, a module 1 i software interface for managing the WiFi radio link signal interface and a pairing module _1.2 for executing the reliable pairing in accordance with the method that is the subject of the present invention.

The pairing module I ₂ may be associated with a temporary and permanent database 1 ₃ and an initialization circuit 1 ₄ is provided which may consist of a push button placed outside the housing constituting the server device considered.

Finally, a short-range interface 1 ₅ may be optionally provided, when it is desirable to reduce the scope of the server of the object of the invention as shown in FIG. 3.

As represented in FIG. 3 above, the pairing module 1 ₂ advantageously comprises at least one module M ₀ for launching the identification process by opening the process pairing from a first identification value of the server device, a module Mi waiting events, these events comprising either the transmission of a request for establishment of a common session key, the key CSK, during the transmission of the request R_CSK, that is to say the transmission of a request for reception of pairing data by a user terminal UT, a request denoted R_UT_G_D in FIG. 2a or the expiry of a delay of Reliable pairing, ie delay P_D_E = 1 represented in step 102c of FIG. 2a.

The pairing module 1 ₂ also comprises a sub-module M ₂ end pairing process called either on expiration of the pairing period reliability or on detection of a number of common session key establishment requests greater than the unit as shown for processing 104, 104b of Figure 2a.

The invention finally covers a computer program recorded on a storage medium comprising a sequence of instructions for execution by a computer or by a server device forming a shared network access point as represented in FIG. 3, this program computer is remarkable in that during the execution of these instructions this program performs the steps of the method of the invention as shown in Figure 1a and Figure 2a in particular.

Claims

1. A method of controlling the connection of a first and a second device, provided with cryptographic resources, characterized in that this method consists of at least:

execute a local initialization command for a certain duration on the first device, and during this period,

launching an identification process on this first device, starting from a first identification value of this first device;

executing, before the end of said initialization, a local initialization command on the second device for temporarily setting said second device and said identification process, via said first device, to initialize the first and second devices; being executed according to a common initialization step; and, during said common initialization step,

- establish a common session key to the first and second device;

encrypting, in said first device, a second local identification value of said first device and a secret key value associated with said first device by means of said common session key according to an encrypted value and transmitting said encrypted value of said first device second device; and, at the level of said second device,

decrypting said encrypted value of said second local identification value and said secret key value associated with said first device by means of the common session key; and

configuring said second device from said second local identification value and said secret key value for connection by pairing with said first device,

2. Method according to claim 1, characterized in that it further comprises: transmitting by said second device to said first device a public route for transmitting said session key as an encrypted value from the first to the second device;

the decryption of said encrypted value of said session key by said second device to restore to the second device said common session key.

3. Method according to claim 2, characterized in that it further comprises generating said common session key in said first device in the form of a sequence of random bits.

4. Method according to one of claims 1 to 3, characterized in that said first device being a shared network access point forming a server device, said server device executes, following the execution of said local initialization command by actuating a trigger button and said launching step of an identification process by opening the pairing process from said first identification value:

an event waiting step, said events comprising at least either the transmission of a common session key establishment request or the transmission of a pairing data reception request by said second device; or the expiration of a pairing delay;

an end of pairing process step called either on expiration of said pairing delay, or on detection of a number of common session key establishment requests greater than unity.

5. Method according to claim 4, characterized in that the waiting for the transmission by said second device of a common session key establishment request is formed by a return loop to the waiting step of events including a step of processing any session key establishment request.

6. Method according to claim 4 or 5, characterized in that waiting for the transmission of a request for reception of pairing data by said second device is formed by a feedback loop. at the event waiting stage conditional on the non-expiration of said pairing delay and the absence of reception of a common session key establishment request and including a step of processing any request for reception pairing data.

The method of claim 5, characterized in that said step of processing any session key establishment request includes at least controlling the reception of a number of common session key establishment requests greater than i'unité.

Method according to claims 6 to 7, characterized in that, for a number of session key establishment requests greater than unity, said step of processing any pairing data reception request includes at least The transmission by said server device of an error message and the call of the end of pairing step.

9. Method according to one of claims 1 to 8, characterized in that said second device being a shared network client terminal, iedit method includes at least:

a step of inviting the user of said terminal to execute said local initialization command on said first device, forming an access point to this shared network,

a paired shared network search scan step; and on detection of a server device constituting an access point _"

a step of temporarily checking the connection of said client terminal to said access point; and, on successful provisional connection,

a transmission control step of a known session key establishment request; and, on receipt of an acknowledgment of receipt of the common session key establishment request,

a step of transmitting control of a query of pairing data by scanning; and, upon receiving pairing data,

a step of controlling configuration of pairing and connection of the client terminal to said server device constituting an access point.

10. Method according to claim 9, characterized in that, in the absence of detection of a server device constituting an access point, said method comprises a step of returning to the step of inviting the user of said client terminal conditional on a choice by this user either of the repetition of the execution of said local command, or of the execution of a connection classic.

11. The method of claim 9 or 10, characterized in that, on detecting a plurality of server devices constituting an access point, said method comprises another step of returning to the user invitation step. said client terminal conditional to a choice timed by the user is the repetition of the execution of said local command, or the execution of a conventional connection.

12. Method according to one of claims 9 to 11, characterized in that on lack of detection of a server device constituting an access point, unsuccessful provisional connection, on the existence of a session key already received or expiration of the pairing delay, on receipt of an error message of the first device receiving a number of requests to establish a common session key greater than unity or failure of the step of configuration control of the client terminal to said server device said method comprises a loop back to said step of inviting the user of said client terminal.

13. Device for connecting user terminals in shared network forming an access point to this shared network and operating as a server device vis-à-vis client terminals, this connection device comprising at least a radio link signal interface controlled by a pairing module and an initialization circuit, characterized in that said pairing module comprises at least:

a sub-module (MO) for launching an identification process by opening the pairing process from a first identification value of said server device,

an event waiting sub-module (M1), these events comprising either the transmission of a common session key establishment request or the transmission of a request for reception of pairing data by a terminal customer user or the expiration of a trusted pairing period; a sub-module (M2) at the end of the pairing process, called either on expiration of said trusted pairing delay, or on detection of a number of common session key establishment requests greater than unity.

14. Computer program comprising a sequence of instructions stored on a storage medium for execution by a computer or a server device forming a shared network access point, characterized in that during the execution of these instructions said program executes the steps of the method according to the invention according to claims 1 to 8.