Abstract:
A secure messaging channel is necessary especially when the message involves confidential transactions, for example a bank transaction which involves funds transfer and other additional information. The present disclosure describes securing message. The method of securing a message comprises providing a personal identification number by the user, wherein the personal identification number is associated to a unique number of a user. The unique number can be a mobile number. The correct personal identification number invokes the one-time password generator. The one time password generator accesses a metadata which comprises a value stored. The value stored in the metadata is retrieved to generate a dynamic key. The dynamic key is converted to a symmetric encryption key to encrypt the data. The dynamic key can also be converted to a symmetric decryption key to decrypt the data.

Description:
This application claims the benefit of Indian Patent Application Filing No. 1194/CHE/2011, filed Apr. 7, 2011, which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to secure data transactions, and particularly, to a system and a method for securing a data transaction without exchanging keys between a server and a client. 
     BACKGROUND 
     Using textual messages to perform a secure mobile transaction(s) is a challenge today considering the various ways it could be exploited to gain credentials of a user by a nefarious hacker. The short message service (SMS) communication channel is not designed to carry a secured data. SMS transmission can also be affected by errors in the aggregator network and there are cases where the SMS meant for a particular user mobile number has been wrongly forwarded to another user&#39;s mobile number. To address such issues, in the prior art, there exist solutions that secure the SMS channel, that is, in particular secure mobile transactions. However, such methods of securing mobile transactions need secure keys to be exchanged between the server and the mobile device of the user. So, there is a need in the art to build a solution, which could establish mobile transactions securely without exchange of keys. 
     SUMMARY OF THE INVENTION 
     Aspects of the disclosure relate to a method and a system to secure a message without exchange of keys. The present disclosure describes methods that would provide increased level of security without exchange of keys. 
     According to the one aspect of the present disclosure, a method of securing mobile transactions includes providing a personal identification number. The personal identification can be manually entered by a user on a device. The personal identification number is associated with a unique number of the user. The unique number may be a mobile number of the user. The personal identification number invokes a one-time password generator, which is present on a client device. An application running on a device can be a downloadable application or a browser, wherein the browser may use scripts such as java scripts. 
     The one-time password generator accesses a metadata, which, for example, can be a seed file which contains a value. The value present in the metadata or the value along with the personal identification number can be used to generate a dynamic key. In accordance with various embodiments of the present invention, there are two copies of the metadata, one on the client side and the other at the server side. The user is identified by the same metadata both at the client side and the server side. The dynamic key is converted to a symmetric encryption key that can be used to encrypt a data that is being sent from the client side to the server side. The dynamic key may also be used to convert to a symmetric decryption key that can be used to decrypt the data being received from the client. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the present invention will be better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a flow chart illustrating a method  100  for securing a message, in accordance with an embodiment of the present invention; 
         FIG. 2  is a block diagram illustrating a system  200  for securing a message, in accordance with an embodiment of the present invention; 
         FIG. 3  is an example embodiment of the present disclosure; and 
         FIG. 4  is a system illustrating a generalized computer network arrangement, in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure proposes a method for securing an unsecured message.  FIG. 1  is a flow chart illustrating a method  100  for securing a message, in accordance with an embodiment of the present invention. Method  100  describes the steps involved in a securing a mobile transaction without exchanging keys. Method  100  includes a step  110  wherein a user provides an input to the method on to a client device. In accordance with various embodiments of the present invention, the user provides a personal identification number (PIN) as an input. The PIN may be an alpha numeric value, which may also include special characters. Further, the PIN is associated with a unique number including, but not limited to, a mobile number, an internet protocol address, unique number assigned to an application and a medium access control number. In accordance with an embodiment, the user may also enter a username and a password along with the PIN as an input. 
     At step  120 , a one-time password generator is invoked using the PIN. It should be noted that only the correct PIN invokes the one time password generator. The one-time password generator may be any one-time password generator known in the art. 
     At step  130 , on entering of the correct PIN by the user, the metadata is accessed and the value present in the metadata is unlocked. The metadata may be a seed file that contains a value. In accordance with various embodiments, the value may include, but is not limited to, a counter value, a clock value and a clock pulse. Each user is identified by the metadata that is present both on a client side and the server side. It should be noted that the values present in the metadata, both on the client side and the server side, are synchronized. For example, the initial value may be set to zero. Subsequently, every time the value present in the metadata file is accessed, the values are incremented or decremented both on the client side and the server side simultaneously to keep the values synchronized. 
     At step  140 , a dynamic key is generated by referring to the value or the value along with the personal identification number stored in the metadata file. In accordance with an embodiment, a new dynamic key is generated for every session during a transaction, in accordance with another embodiment; a new dynamic key is generated for every transaction between the server and the client. Further, every dynamic key generated may be stored and referred to at a later point in time. 
     At step  150 , the dynamic key is converted to a symmetric encryption key at the client side to encrypt the data from the client side and send it to the server side. The data may include, but is not limited to, a short message service (SMS), a multimedia message and an email. Further, the symmetric encryption key may be in any of a 32-bit, a 64-bit, a 128-bit and a 256-bit or any other format. It should be noted that the symmetric encryption key by itself is not sent to the server; instead, the symmetric key is used to encrypt the data and the encrypted data is sent to the server. Hence, there is no exchange of the key between the client and the server. Further, when the encrypted data is received at the server side, the encrypted data is associated with a unique number from which it is sent. The PIN is retrieved from a user profile using the unique number. Further, the dynamic key is converted to a symmetric decryption key at the server side. The symmetric decryption key may be any of a 32-bit, a 64-bit, a 128-bit, and a 256-bit or any format. 
       FIG. 2  is a block diagram illustrating a system  200  for securing a message, in accordance with an embodiment of the present invention. System  200  includes a client  205  and a server  206 . Client  205  includes a user input  210 , a data receiving module  220 , a first data processing module  230 , a data encrypting module  240  and a data transmitting module  250 . Server  206  includes a first data receiving module  260 , a data mapping module  270 , a second data processing module  280  and a data decrypting module  290 . The user input  210  may be a personal identification number (PIN). The user input  210  may also include a username and a password entered along with the PIN on a client device. 
     The first data processing module  230  receives the input from the data receiving module  220 . The data receiving module  220  includes a first one-time password generator (not indicated in the figure). In accordance with various embodiments, the first one time password generator is invoked when a correct PIN is entered. The first data processing module  230  further includes a seed file (not indicated in the figure) that stores a first instance of a value. The value may be any of a counter value, a clock value, and a clock pulse. Both client  205  and server  206  include a copy of the seed file. Further, the values present on client  205  and server  206  are synchronized. In accordance with an embodiment, the value present in the seed file is initialized to zero and the value is either incremented or decremented both on client  205  and server side  206  every time the seed file is accessed. 
     The first one time password generator accesses the seed file, and by referring to the first instance of the value, generates the first dynamic key. The first dynamic key is stored for that session, that is, until the user logs out. The first data processing module  230  may also be configured to store previously generated dynamic keys and the one time passwords generated. In accordance with an embodiment, the number of dynamic keys or one time passwords generated can be defined by a window size, which may be a numerical value. For example, if the value of the window size is specified as three, then the first data processing module  230  can store a maximum of three previously generated dynamic keys or one time passwords generated. The data encrypting module  240  converts the first dynamic key to a first symmetric encryption key. The first symmetric encryption key may be in any of a 32-bit, a 64-bit, a 128-bit, and a 256-bitor any format. The first symmetric encryption key is used to encrypt the data. The data may be a short message service (SMS), or an email or a multimedia message. The data transmitting unit  250  is configured to receive the encrypted data from the data encrypting module  240 . The data transmitting unit  240  transmits the encrypted data to server  206  through an unsecured communication channel (not shown in the figure). The unsecured communication channel may be a wireless communication channel or a wired communication channel. 
     Further, the encrypted data is received at server  206  by the first data receiving module  260 . The first data receiving module  260  is also configured to send the encrypted data to the data mapping module  270 . The data mapping module  270  associates the encrypted message with a particular user profile by a unique number. In accordance with various embodiments, the unique number may be any of a mobile number, an internet protocol address and a medium access control number. By using the unique number, the data mapping module  270  retrieves the user profile information present in one of the service provider databases. The second data processing module  280  is configured to receive the user profile information from the data mapping module  270 . The second data processing module  280  retrieves the PIN from the user profile information and the second one-time password generator which is invoked by the personal identification number. The second one time password generator accesses the seed file, refers to the second instance of the value stored in the seed file and generates a second dynamic key. The second dynamic key is stored for that session, that is, until the user logs out. The second data processing module  280  may also be configured to store previously generated dynamic keys and also the one time passwords generated. In accordance with an embodiment, the number of dynamic keys or one time passwords generated may be defined by a window size, which can be a numerical value. For example, if the value of the window size is three, then the second data processing module  280  can store a maximum of three previously generated dynamic keys or one time passwords generated. 
     In the embodiment of the present disclosure the first dynamic key on client  205  and the second dynamic key on server  206  are the same since they are synchronized. In other words, the first instance of the value stored on client  205  and the second instance of the value on server  206  are always synchronized and are identical. The data decrypting module  290  is configured to receive the second dynamic key and convert it to a first symmetric decryption key. The first symmetric decryption key may be any of a 32-bit key, a 64-bit key, a 128 bit key, and a 256-bit key. The first symmetric decryption key is used to decrypt the encrypted data. Decryption of the encrypted data is successful if the right user is identified and counters are synchronized. If the decryption fails, then server  206  retries with multiple keys generated by multiple one time passwords based on the window size set to identify any counter synchronization problems at server  206 . Once the decryption is successful, the right counter value is set. 
     The embodiment of the present disclosure can be further explained considering an example.  FIG. 3  is an example embodiment of the present disclosure. At step  1   315 , the user provides the username, password and the personal identification number (PIN), which is accepted by the data receiving module  220  (shown in  FIG. 2 ) as an input to login page on the client device  305 . The first data processing module  230  (shown in  FIG. 2 ) is configured to accept input from step  315  and the correct PIN invokes the first one-time password generator present in the first data processing module  230 . 
     At step  320 , a login request is sent to the server  310 . A first one time password generator accesses a seed file and retrieves the first instance of a value stored in the seed file to generate a first dynamic key. The first dynamic key is stored for that session, that is, until the user logs out. The first data processing module  230  may also be configured to store the previously generated dynamic keys and also the one time passwords generated. In accordance with an embodiment, the number of dynamic keys or one time passwords generated can be defined by a window size, which may be a numerical value. For example, if the value of the window size is three, then the second data processing module  280  can store a maximum of three previously generated dynamic keys or one time passwords generated. The data encrypting module  240  (shown in  FIG. 2 ) converts the first dynamic key to a first symmetric encryption key, which preferably is a 128 bit encryption key. The username and password are encrypted using the first symmetric encryption key and the data transmitting unit  250  (shown in  FIG. 2 ) sends the encrypted data to the server  310  using a short message service (SMS). 
     At step  325 , the encrypted data is received from the client  305  followed by decryption of the data and sending of a response to the client  305 . On receiving the encrypted data at the server  310 , the first data receiving module  260  (shown in  FIG. 2 ) receives the encrypted data and sends the data to the data mapping module  270  (shown in  FIG. 2 ). The data mapping module  270  retrieves the PIN present in user profile information by mapping the unique number from which the encrypted data is sent. In this example, the unique number is the mobile number from which the encrypted data is sent. The data mapping module  270  retrieves the PIN from the user profile by mapping the corresponding mobile number of the user. 
     The second data processing module  280  (shown in  FIG. 2 ) receives the PIN from the data mapping module  270  and invokes a second one-time password generator. The second one time password generator access a metadata file, which, in this example, is a seed file to retrieve the second instance of the value stored. A second dynamic key is generated by referring to the second instance of the value stored. The second dynamic key is stored for that session, that is, until the user logs out. The second data processing module  280  may also be configured to store the previously generated dynamic keys and also the one time passwords generated. In accordance with an embodiment, the number of dynamic keys or one time password generated can be defined by a window size, which may be a numerical value. For example, if the value of the window size is three, then the second data processing module  280  can store a maximum of three previously generated dynamic keys or one time passwords generated. The data decrypting module  290  (shown in  FIG. 2 ) is configured to receive the second dynamic key from the second data processing module  280  and convert the second dynamic key to a first symmetric decryption key, which, in this example, is a 128-bit key. The first symmetric encryption key is used to decrypt the data. The encrypted username and password are extracted from the encrypted data and the login response  325  is sent to the client  305 . If the username or password is typed wrongly then the server sends an appropriate error SMS. Decryption is successfully performed if the right user is identified and counter values in the seed file are synchronized. If decryption fails, then server  206  (shown in  FIG. 2 ) retries with multiple keys generated by multiple one time passwords based on the window size set to identify any counter synchronization problems at the server  206  and the right counter value is set based on the successful decryption. 
     In the embodiment of the present disclosure step  2   320  occurs every time a message is being sent from the client  305  to the server  310 . 
     Further, at step  4   330 , the client  305  sends an SMS having a transaction request and waits for the server  310  to respond for a predefined period, for example, three minutes, which is described as time out period  316 . The client  305  is not allowed to perform any new transactions within the time out period  316 . In case of multipart SMS, if one or more pieces of the multipart SMS arrive after three minutes, an appropriate error message is displayed. Once client request SMS reaches the server  310 , the transaction is carried out to completion and the response is sent to the client  305  at step  5   335 . Further, if the response does not reach the client  305  within three minutes, the appropriate error message is displayed to the user and the user may carry out other transactions. 
     For further transactions, steps  4 - 6  are repeated and the same one time password generated on both client  305  and server  310 , which is stored in the heap, will be used. This heap may be defined as a window size and the number of one time passwords generated can be modified by setting a limit of storing the one time passwords generated. On successful response to the client  305 , the client  305  sends a log out request SMS to the server  310 , which is indicated in step  6   340 . The server  310  responds with a corresponding log out message to client  302  as indicated in step  7   345 . 
     In accordance with an embodiment of the present invention, the server  310  stores the time at which it receives the SMS from the client  305 , which is used along with the mobile number to maintain a session with the client  305 . 
     In accordance with another embodiment of the present invention, a different dynamic key can be used for every transaction. 
     Further, in accordance with another embodiment of the present disclosure, a multi-part message can be sent to the server  310  in the following format. 
                                                             message   :   n/N   Reference   Msg           Identifier           value                        
Where
 
msg: is a simple text representing start of message id part.
 
Message identifier: helps to associate the request and response
 
Reference value: helps to take decision on whether a new key or a old key needs to be used, key size, encryption or decryption algorithm.
 
n/N: is nth part of N parts.
 
Case 1: When all the pieces of multipart message arrive within 3 minutes, they are assembled and displayed on client  305 .
 
Case 2: When one or more pieces of multipart message arrive after 3 minutes, appropriate error message is displayed on the client  305 .
 
     In another embodiment of the present disclosure, the first data processing module  230  on client  205  can use the context information such as type of network, condition of network, security rating of the network, profile of the user, handset profile etc to decide: use a new one time password by invoking the one time password generator or use the previous or old one time password; or a new encryption key can be generated using the one time password used in the previous step, and the selected key generation algorithm or an old encryption key can be used. 
     The data encrypting unit  240  can select the encryption algorithm based on the context information such as type of network, condition of network, security rating of the network, profile of the user, handset profile etc. and use the encryption key generated above to encrypt the message to be sent wherein a reference value is embedded in the message header. The reference value is chosen based on one or combination of the following: whether new password or old password; or key generation algorithm; or encryption algorithm and sends it to the server  206 . 
     The second data processing module  280  uses the reference value to identify whether old key can be used or new key needs to be generated. If new key needs to be generated then the one time password generator module is used to generate the dynamic one time password using the identified personal identification number. The data decrypting module  290  uses the reference value, to select the right key generation algorithm and generates the decryption key of appropriate size from the dynamic one time password and decrypts the data. 
     One or more of the above-described techniques may be implemented in or involve one or more computer systems.  FIG. 4  illustrates a generalized example of a computing environment  400 . The computing environment  400  is not intended to suggest any limitation as to scope of use or functionality of described embodiments. 
     With reference to  FIG. 4 , the computing environment  400  includes at least one processing unit  410  and memory  420 . In  FIG. 4 , this most basic configuration  430  is included within a dashed line. The processing unit  410  executes computer-executable instructions and may be a real or a virtual processor. In a multi-processing system, multiple processing units execute computer-executable instructions to increase processing power. The memory  420  may be volatile memory (e.g., registers, cache, RAM), non-volatile memory (e.g., ROM, EEPROM, flash memory, etc.), or some combination of the two. In some embodiments, the memory  420  stores software  480  implementing described techniques. 
     A computing environment may have additional features. For example, the computing environment  400  includes storage  440 , one or more input devices  450 , one or more output devices  460 , and one or more communication connections  470 . An interconnection mechanism (not shown) such as a bus, controller, or network interconnects the components of the computing environment  400 . Typically, operating system software (not shown) provides an operating environment for other software executing in the computing environment  400 , and coordinates activities of the components of the computing environment  400 . 
     The storage  440  may be removable or non-removable, and includes magnetic disks, magnetic tapes or cassettes, CD-ROMs, CD-RWs, DVDs, or any other medium which may be used to store information and which may be accessed within the computing environment  400 . In some embodiments, the storage  440  stores instructions for the software  480 . 
     The input device(s)  450  may be a touch input device such as a keyboard, mouse, pen, trackball, touch screen, or game controller, a voice input device, a scanning device, a digital camera, or another device that provides input to the computing environment  400 . The output device(s)  460  may be a display, a television, a hand held device, a head mounted display or a Kiosk that provides output from the computing environment  400 . 
     The communication connection(s)  470  enable communication over a communication medium to another computing entity. The communication medium conveys information such as computer-executable instructions, audio or video information, or other data in a modulated data signal. A modulated data signal is a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media include wired or wireless techniques implemented with an electrical, optical, RF, infrared, acoustic, or other carrier. 
     Implementations may be described in the general context of computer-readable media. Computer-readable media are any available media that may be accessed within a computing environment. By way of example, and not limitation, within the computing environment  400 , computer-readable media include memory  420 , storage  440 , communication media, and combinations of any of the above. 
     Having described and illustrated the principles of our invention with reference to described embodiments, it will be recognized that the described embodiments may be modified in arrangement and detail without departing from such principles. It should be understood that the programs, processes, or methods described herein are not related or limited to any particular type of computing environment, unless indicated otherwise. Various types of general purpose or specialized computing environments may be used with or perform operations in accordance with the teachings described herein. Elements of the described embodiments shown in software may be implemented in hardware and vice versa. 
     In view of the many possible embodiments to which the principles of our invention may be applied, we claim as our invention all such embodiments as may come within the scope and spirit of the following claims and equivalents thereto.