Abstract:
Methods and systems for maintaining mobile terminal information for secure email communications are provided. Information concerning multiple mobile terminals are maintained. Such information may include encryption information and an identifier for each mobile terminal. A service activation code that includes encryption information and an identifier from an authenticated user of the mobile terminal is received. The encryption information may be provided to a connectivity function for use in establishing an encrypted data channel. The established encrypted data channel may then be used to convey e-mail communications to and from the mobile terminal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional and claims the priority benefit of U.S. patent application Ser. No. 11/282,607 filed Nov. 21, 2005, now U.S. Pat. No. 7,706,781 which claims the priority benefit of U.S. provisional application No. 60/651,082 filed Feb. 9, 2005, U.S. provisional application No. 60,650,975 filed Feb. 9, 2005, Finnish patent application number 20055038 filed Jan. 26, 2005, and Finnish patent application number 20045451 filed Nov. 22, 2004, the disclosures of the aforementioned applications being incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to methods and equipment for establishing data security in an e-mail service between an e-mail server and a mobile terminal. 
     2. Description of the Related Art 
     Data security in an e-mail service is achieved by using cryptographic techniques in which traffic in a potentially insecure channel is encrypted using cryptographic information, commonly called encryption keys. A problem underlying the invention relates to distributing such encryption information. Prior art techniques for distributing the encryption information are commonly based on public key encryption techniques, such as Diffie-Hellman. A problem with this approach is that the parties have to trust the underlying mobile network and its operator, which they are surprisingly reluctant to do. Another problem is that mobile terminals tend to have small and restricted user interfaces. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a method and system for implementing the method so as to alleviate the above problems. The object of the invention is achieved by the methods and systems which are characterized by what is stated in the independent claims. Preferred embodiments of the invention are disclosed in the dependent claims. 
     The invention is partially based on the discovery of a surprising problem that has been found as a result of extensive market research. Although clients of mobile networks normally trust their mobile operators as regards voice calls, they are surprisingly reluctant to trust the mobile operators as regards data services, such as e-mail service. The reluctance to trust mobile operators in respect of data services makes public-key interchange schemes unattractive. 
     Some embodiments of the present invention include methods and systems for maintaining mobile terminal information for secure email communications. Such methods may include maintaining information concerning multiple mobile terminals. Such information may include encryption information and an identifier for each mobile terminal. Methods may further include receiving a service activation code that includes encryption information and an identifier from an authenticated user of the mobile terminal. The encryption information may be provided to a connectivity function for use in establishing an encrypted data channel. Methods may yet further include using the established encrypted data channel to convey e-mail communications to and from the mobile terminal. 
     Various embodiments of the present invention include systems and computer-readable storage media including programs for performing methods for maintaining mobile terminal information for secure email communications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which 
         FIG. 1  shows an exemplary system architecture in which the invention can be used; 
         FIG. 2  shows procedure steps for establishing a secure connection. 
     
    
    
     DETAILED DESCRIPTION 
     The invention is applicable to virtually any mobile e-mail system architecture.  FIG. 1  shows an exemplary system architecture which is supported by the owner of the present application. Reference numeral  100  denotes a host system that is able to send and receive e-mail messages. Reference numeral  102  denotes a mobile terminal, also able to send and receive e-mail messages. The e-mail messages may originate or terminate at external e-mail terminals, one of which is denoted by reference numeral  104 . The invention aims at improving cooperation between the host system  100  and mobile terminal  102  such that they can use a single e-mail account as transparently as possible. This means, for example, that the users of the external e-mail terminals  104 , when sending or receiving e-mail, do not need to know if the user of the host system  100  actually uses the host system  100  or the mobile terminal  102  to communicate via e-mail. The transparency also means that e-mail manipulation at the mobile terminal  102  has, as far as possible, the same effect as the corresponding e-mail manipulation at the host system  100 . For example, e-mail messages read at the mobile terminal  102  should preferably be marked as read at the host system. 
     Reference numeral  106  denotes a data network, such as an IP (Internet Protocol) network, which may be the common Internet or its closed subnetworks, commonly called intranets or extranets. Reference numeral  108  denotes an e-mail server and its associated database. There may be separate e-mail servers and/or server addresses for incoming and outgoing e-mail. The database stores an e-mail account, addressable by means of an e-mail address, that appears as a mailbox to the owner of the e-mail account. In order to communicate with mobile terminals  102 , the data network  106  is connected, via a gateway  112  to an access network  114 . The access network comprises a set of base stations  116  to provide wireless coverage over a wireless interface  118  to the mobile terminals  102 . 
     Reference numeral  110  denotes a messaging centre that is largely responsible for providing the above-mentioned transparency between the host system  100  and the mobile terminal  102 . The system architecture also comprises a connectivity function  120 , whose task is to push e-mail messages to the mobile terminal. In the embodiment shown in  FIG. 1 , the connectivity function  120  is considered a physically integral but logically distinct element of the messaging centre  110 . 
     The mobile terminal  102  may be a pocket or laptop computer with a radio interface, a smart cellular telephone, or the like. Depending on implementation, the host system  100 , if present, may have different roles. In some implementations the host system  100  is optional and may be a conventional office computer that merely acts as the mobile terminal user&#39;s principal computer and e-mail terminal. In other implementations the host system may act as a platform for a single user&#39;s connectivity function, in addition to being an office computer. In yet other implementations the host system  100  may comprise the connectivity function for several users. Thus it is a server instead of a normal office computer. 
     We assume here that the access network  114  is able to establish and maintain a tunnel  122  between the messaging centre  110  and the mobile terminal  102 . For instance, the tunnel may be set up using GPRS Tunneling Protocol (GTP) or its later derivatives, or any other suitable tunneling protocol. 
       FIG. 1  shows an embodiment in which the messaging centre  110  is largely responsible for e-mail transport to/from the mobile terminal  102  via the access network  114 , while a separate connectivity function  120  is responsible for data security issues. The connectivity function  120  may be physically attached to or co-located with the messaging centre  110 , but they are logically separate elements. Indeed, a definite advantage of the separate connectivity function  120  is that it can be detached from the messaging centre, for instance, within the company that owns the host system  100  or the e-mail server  108 . For a small number of users, the connectivity function  120  can be installed in each host system  100 , or the host system  100  can be interpreted as a separate server configured to support multiple users. It is even possible to implement some or all the above-mentioned options. This means, for example, that there is one or more messaging centers  110  that offer services to several network operators, or they may be a dedicated messaging centre for each network operator (somewhat analogous to short messaging centers). Each messaging centre  110  may have an integral connectivity function  120  to support users who don&#39;t wish to install a separate connectivity function in a host system  100 . For users who do install a separate connectivity function  120  in their host systems  100 , such connectivity functions bypass the connectivity function in the messaging centre  110  and address the messaging centre  110  directly. 
     A real e-mail system supports a large number of mobile terminals  102  and tunnels  122 . In order to keep track of which e-mail account and which tunnel belongs to which mobile terminal, the messaging centre  110  and the connectivity function collectively maintain an association  124 ,  124 ′ for each supported mobile terminal. Basically, each association  124 ,  124 ′ joins three fields, namely an e-mail address  124 A assigned to the mobile terminal or its user, encryption information  124 C and a temporary wireless identity  124 D of the mobile terminal in the access network. The embodiment shown in  FIG. 1  also employs a terminal identifier  124 B which may be the same as the e-mail address  124 A of the mobile terminal  102 , in which case the association  124  actually associates three information items. Alternatively, the terminal identifier  124 B may be an identifier arbitrarily assigned to the mobile terminal. In a preferred implementation the terminal identifier  124 B is the mobile terminal&#39;s equipment identifier or its derivative. The encryption information  124 C is preferably related to the mobile terminal&#39;s equipment identity and is preferably generated by the mobile terminal itself, so as to ensure that no other terminal besides the one used for creating the encryption information  124 C will be able to decrypt incoming encrypted e-mail messages. The temporary wireless identity  124 D may be the identifier of the tunnel  122  to the mobile station. Of course, the tunnel identifier is not permanent and is only known when a tunnel exists. 
       FIG. 2  shows a secure e-mail provisioning technique in which the host system  100  authenticates the user of the mobile terminal  102 . In step  2 - 1  the client software in the mobile terminal  102  generates and displays a service activation code. In step  2 - 2  the host system  100  authenticates the person who enters the service activation code. Instead of a dedicated authentication step, the technique may rely on the authentication of the underlying e-mail system, such as user name and password combination. After all, the e-mail provisioning need not be more secure than the underlying e-mail system. In step  2 - 3  the service activation code is then conveyed off-line to the host system  100 . The idea of the off-line communication is to eliminate any chance of eavesdropping before secure a communication channel can be established. For instance, the service activation code may be entered manually or via a local connection, such as a wired or optical interface or a short-range wireless interface, such as Bluetooth™. Finally, in step  2 - 4 , the mobile terminal&#39;s service activation code is registered with the connectivity function  120 . 
     The service activation code is closely related to an encryption key to be used in future communications between the connectivity function  120  and the mobile terminal  102 . The service activation code and the encryption key may be identical, or one may be a subset of the other, or the encryption key may be derived from the service activation code by means of some, preferably unpublished, algorithm. The fact that the service activation code and the encryption key are closely related to each other ensures that the terminal used in the authentication process is the terminal used to access the e-mail service afterwards. 
     Thus the idea of conveying the service activation code to the connectivity function  120  via the host system  100  solves both the security-related and user interface-related problems mentioned above. If there is no host system  100  that can authenticate the mobile terminal and its user. Instead, the user may enter the provisioning data to the connectivity function via some suitable connection. The provisioning data entered by the user may be checked by sending a trial e-mail message and attempting to read it. If the check succeeds, it is regarded as the authentication. Yet another way is to convey the service activation code to a dedicated support person who performs the authentication (e.g. by recognizing the person&#39;s face or voice) and enters the service activation code into the connectivity function  120 . The connectivity function  120  now stores an association (item  124  in  FIG. 1 ) between the e-mail address  124 A and encryption information  124 C. 
     The mobile terminal preferably generates the service activation code based on the encryption key, the mobile terminal&#39;s identifier and a checksum. A benefit of the checksum is that invalid service activation codes can be detected, considering the fact that the service activation code may be conveyed via channels that are immune to electrical eavesdropping but very prone to human errors. For example, the service activation code may be read visually from the mobile terminal&#39;s display and entered manually into another terminal. 
     The mobile terminal&#39;s identifier can be its IMEI, IMSI, MSISDN, or other network identifier. A benefit of encoding the mobile terminal&#39;s identifier and the encryption key into the service activation key is that the connectivity function  120  needs both to communicate with the mobile terminal. The connectivity function  120  needs the mobile terminal&#39;s identifier in order to send data to the mobile terminal. The connectivity function  120  also needs the encryption key because it is the mobile terminal&#39;s peer entity as regards encryption. As soon as the connectivity function  120  receives knowledge of the mobile terminal&#39;s identifier and the encryption key, it can send the mobile terminal a first message comprising service provisioning settings, after which it can begin sending user traffic, such as new e-mail messages, calendar information and the like. 
     As stated in the description of  FIG. 1 , there are several possible implementations for the connectivity function  120 . For example, it can be installed in a public data network, such as the Internet, as a physically integral element of the messaging centre  110  but logically distinct from it. It can also be installed in a company&#39;s private network within a firewall. It can be installed as a process in each mobile terminal user&#39;s office computer, or one common server can support all mobile users of the company, somewhat analogously to a company&#39;s e-mail server. The advantages of the invention are easiest to see when the connectivity function is dedicated to a particular company and is located within the company&#39;s firewall. This is because in this implementation there are several connectivity functions, and the mobile terminal has no a priori knowledge of which one it should connect to. A coarse solution to this problem is requesting this information from the user, but entering exact configuration information via a small user interface is one of the problems this invention attempts to solve. 
     It is readily apparent to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.