Secure data communication for groups of mobile devices

RELATED APPLICATION

0001This is a Continuation-in-Part Application of U.S. patent application Ser. No. 11/317,136, “Token-Enabled Authentication for Securing Mobile Devices,” filed by Cukier et al., on Dec. 22, 2005, incorporated herein by reference.

FIELD OF THE INVENTION

0002This invention relates generally to communicating data between mobile devices, and more particularly to communicating the data securely.

BACKGROUND OF THE INVENTION

0003Mobile computing and communication devices have increased demand for communicating data, performing business transactions, and mobile computing. Mobile devices can easily be lost or stolen putting stored data at risk. Wireless communications are subject to interception.

0004Access to the data stored on the mobile devices can be controlled with authentication mechanisms, such as passwords, biometrics, and tokens. For password-authentication, the user enters a name and password to access data. However, after user authentication, the data are vulnerable to unauthorized access. For biometric authentication, the user supplies a biometric feature, such as fingerprint, for authentication. However, biometric authentication mechanisms are complex and tend to have a high false-negative rate.

0005Token enabled user authentication is described in detail in the parent application.

0006U.S. Published Application 2003/0233538 describes a communication system that provides secure collaborative group communication among a subset of nodes in a mobile ad hoc network. That system uses secure virtual communication channels between member nodes of the network with a topology based reverse path forward network layer protocol.

0007U.S. Pat. No. 5,970,144 describes a system and method for enabling sensitive authentication information to be under the control of an authentication center (AC) and transmitting only non-sensitive authentication information to the AC.

SUMMARY OF THE INVENTION

0008The embodiments of the invention provide a system and method to protect data communicated between members of a group of mobile devices using a wireless channel. Each mobile device is associated with a physical token. The mobile device can not be operated unless the token is within communication range of the mobile device. A range of the wireless communication is relatively small, e.g., meters or less.

0009The method involves three phases of operation: user authentication, key distribution, and data communication. The authentication phase involves token-base authentication to enable operation of the mobile device by the authenticated user. The key distribution phase involves the distribution of keys among the member mobile devices. The data communication phase involves the actual sharing of secured data amongst the group participants. The data are encrypted using the distributed keys. Short range wireless communication can be used for the authentication, distribution and data communication phases.

BRIEF DESCRIPTION OF THE DRAWINGS

0010<figref idref="DRAWINGS">FIG. 1</figref> is a block diagram of a member mobile device and an associated physical token according to an embodiment of the invention;

0011<figref idref="DRAWINGS">FIG. 2</figref> is a block diagram of a group of member mobile devices and associated tokens including a group leader mobile device according to an embodiment of the invention;

0012<figref idref="DRAWINGS">FIG. 3</figref> is a block diagram of a method for securely communicating data among the member mobile devices of <figref idref="DRAWINGS">FIG. 2</figref> using, in part, a removable memory;

0013<figref idref="DRAWINGS">FIG. 4</figref> is a block diagram of a method for securely communicating data among the member mobile devices of <figref idref="DRAWINGS">FIG. 2</figref> using, in part, images; and

0014<figref idref="DRAWINGS">FIG. 5</figref> is a block diagram of a method for securely communicating data among the member mobile devices of <figref idref="DRAWINGS">FIG. 2</figref> using, in part, a wireless channel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

0015<figref idref="DRAWINGS">FIG. 1</figref> shows one member <b>110</b> of a group of mobile devices. The mobile device is associates with a physical token <b>130</b>. The mobile device can be a PDA, laptop, camera, removable storage, portable music or video player, mobile telephone, and the like. The mobile device and token <b>130</b> can communicate with each other via a wireless channel <b>140</b>. The mobile device can also include display interface <b>331</b> and a camera interface <b>332</b>.

0016The token <b>130</b> stores a first key k₁<b>101</b> and a binding key k_b<b>103</b>. The mobile device stores a second key k₂<b>102</b> and the binding key k_b, <b>103</b>. The keys can be stored in memories of the devices and tokens. In one embodiment, the mobile device can also include a removable memory, e.g., a memory card <b>105</b>.

0017A user authentication phase, that uses the keys k₁, k₂, and k_bis described in related U.S. patent application Ser. No. 11/317,136, “Token-Enabled Authentication for Securing Mobile Devices,” filed by Cukier et al., on Dec. 22, 2005, incorporated herein by reference.

0018<figref idref="DRAWINGS">FIG. 2</figref> shows members of a group <b>200</b> of mobile devices <b>110</b>. Each member is associated with one of the tokens <b>130</b>. One member <b>110</b>′ of the group <b>200</b> is designated as a group leader.

0019It is desired to securely communicate data between the members of the group of mobile devices during a group session. Therefore, keys need to be distributed among the members during a key distribution phase.

0020<figref idref="DRAWINGS">FIGS. 3-5</figref> shows key distribution according to embodiments of the invention.

0021Physical Key Distribution

0022Each member <b>110</b> has a unique identification ID_N<b>301</b>. A group session key k_ses<b>302</b> is stored by the group leader <b>110</b>′.

0023Each token of each group member generates a member key k_mem<b>303</b> The token can generate this key using some random generation process. The member key is encrypted (E) <b>310</b> using the associated binding key k_b<b>103</b> and passed to the mobile device, using the wireless channel <b>140</b>. The member mobile device decrypts and stores the member key <b>303</b>. In one embodiment, the session key and the member key is also stored on the removable memory <b>105</b>.

0024The removable memory <b>105</b> is physically passed to each member, and each member reads the session key k_ses, and stores its ID and member key k_memon the card. The card is passed back to the group leader. The group leader reads the IDs and member keys and stores the IDs and member keys locally in the memory.

0025At this point the group leader can securely communicate <b>320</b> data on the wireless channel <b>140</b> with any member device by encrypting the data with the appropriate member key according to E^k^{<sub2>mem </sub2>}{data}. Members can communicate with each other via the group leader, or members can become group leaders at any time. At the end of the session the session key and member keys can be erased.

0026Visual Key Distribution

0027Instead of physically storing the keys and IDs on the memory card, the member devices can display the IDs and keys on a display interface <b>331</b> as shown in <figref idref="DRAWINGS">FIG. 4</figref>. The display can be encoded as a bar code, for example. A camera interface <b>332</b> can be used by the group leader to acquire an image of the member displays and to recover the IDs and keys. The group leader can then distribute the session key encrypted with the member key to each member via the wireless interface. The members decrypt and store the session key using their member keys. Then, the members can securely communicate <b>320</b> data as described above. Data intended for all members can be encrypted with the session key k_ses, while data intended for a single member can be encrypted with the appropriate member key k_mem. Then, secure communication can proceed as described above.

0028Wireless Key Distribution

0029In this embodiment as shown in <figref idref="DRAWINGS">FIG. 5</figref>, each mobile device has a unique address used for communication, e.g., a telephone number, or some other network address. The addresses of the members are known to the group leader. The address will be used as an address key k_address.

0030Session and member keys are generated as described above. Each group member that wants to participate in securely sharing data during the session encrypts its member key k_memwith the address key k_addressaccording to E^k^{<sub2>address </sub2>}{k_mem}. The encrypted address and member ID is transmitted securely <b>510</b> to the group leader using the wireless channel <b>140</b>.

0031The group leader mobile device decrypts and stores the member keys of the each member. The group leader encrypts the session key with each member key, and distributes <b>520</b> the session key to all participating members using the wireless channel <b>140</b>.

0032The members decrypt and store the session key using their member keys. Then, the members can securely communicate <b>320</b> data as described above. Data intended for all members can be encrypted with the session key k_ses, while data intended for a single member can be encrypted with the appropriate member key k_mem.

0033All keys are erased at the end of the session.

0034Although the invention has been described by way of examples of preferred embodiments, it is to be understood that various other adaptations and modifications can be made within the spirit and scope of the invention. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the invention.