Patent Abstract:
Often, for reasons of wireless bandwidth conservation, incomplete messages are provided to wireless messaging devices. Employing cryptography, for secrecy or authentication purposes, when including a received message that has been incompletely received can lead to lack of context on the receiver&#39;s end. By automatically obtaining the entirety of the message to be included, an outgoing message that includes the received message can be processed in a manner that securely and accurately represents the intended outgoing message. Alternatively, a server can assemble a composite message from a new message and an original message and, in cooperation with a wireless messaging device, encrypt and sign the composite message. Conveniently, security considerations are maintained even in view of bandwidth optimization measures.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from U.S. Provisional Patent Application Ser. No. 61/413,941, filed Nov. 15, 2010, the contents of which are hereby incorporated herein by reference. 
    
    
     FIELD 
     The present application relates generally to mobile wireless electronic messaging and, more specifically, to encrypting a message with the involvement of more than one component. 
     BACKGROUND 
     In one manner of processing (e.g., encrypting) an outgoing e-mail message, a communication application, employed by a given user, transforms the outgoing e-mail message using an algorithm with a public key half of a public-private key pair. The encrypted outgoing e-mail message may then be transmitted. Upon receiving the encrypted e-mail message, the recipient device may be configured to decrypt the received e-mail using a private key half of the public-private key pair. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to the drawings, which show by way of example, embodiments of the present application, and in which: 
         FIG. 1  illustrates an overview of an example system including a mobile communication device and a wireless mail server; 
         FIG. 2  illustrates a schematic representation of components of the mobile communication device of  FIG. 1 ; 
         FIG. 3  illustrates example steps in a first method of processing an electronic message at the mobile communication device of  FIG. 1 , where the processing comprises signing; 
         FIG. 4  illustrates an example dialog to warn a user that an e-mail message will be incompletely included in a response message; 
         FIG. 5  illustrates example steps in the method of  FIG. 3 , where the processing comprises encrypting; 
         FIG. 6  illustrates example steps in a second method of processing an electronic message at the mobile communication device of  FIG. 1 , where the processing comprises signing; 
         FIG. 7  illustrates example steps in a method of processing an electronic message at the wireless mail server of  FIG. 1 , in conjunction with the method of  FIG. 6 ; 
         FIG. 8  illustrates example steps in a third method of processing an electronic message at the mobile communication device of  FIG. 1 , where the processing comprises signing; 
         FIG. 9  illustrates example steps in a method of processing an electronic message at the wireless mail server of  FIG. 1 , in conjunction with the method of  FIG. 8 ; 
         FIG. 10  illustrates example steps of a cross-component message encryption approach; 
         FIG. 11  illustrates example steps in a method of participating, at the wireless mail server of  FIG. 1 , in the cross-component message encryption approach of  FIG. 10 ; 
         FIG. 12  illustrates example steps of cross-component message encryption approach distinct from the cross-component message encryption approach of  FIGS. 10 and 11 ; and 
         FIG. 13  illustrates example steps in a method of participating, at the wireless mail server of  FIG. 1 , in the cross-component message encryption approach of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     When a mobile wireless device is used to receive and transmit e-mail, the mobile wireless device is often associated with a mobile mail server. The mobile mail server manages the transmission of messages to the mobile wireless device to optimize use of the limited resources of a wireless communication channel in the path between the mobile wireless device and the mobile mail server. The mobile mail server may also manage messages transmitted by the mobile wireless device to optimize in a similar fashion. 
     For a first example of optimization of transmission of messages to the mobile wireless device, by only transmitting an initial portion of a first e-mail message to the mobile wireless device, the mobile mail server may conserve wireless resources that would otherwise be consumed by transmitting the entire first e-mail message. 
     It is common, in e-mail communication applications, to include the text of a received e-mail message when composing an e-mail message in response or when forwarding the e-mail message to a further recipient. However, in a mobile communication system, when sending a new e-mail message related to an original e-mail message, the mobile wireless device may only be able to include the initial portion of the original e-mail message in the new e-mail message, since the mobile wireless device may only have the initial portion of the original e-mail message available. Upon receiving the new e-mail message, the cleverly designed mobile mail server may append the remaining (i.e., non-initial) portion of the original e-mail message before forwarding the entire new e-mail message toward its destination. Conveniently, this scheme conserves wireless communication channel resources. 
     However, when a user of the mobile wireless device wishes to sign the new e-mail message, obtaining the efficiency of previously described schemes becomes challenging. 
     For example, consider receipt, at the mobile wireless device, of an initial portion of a first e-mail message. The user of the mobile wireless device reviews the initial portion of the first e-mail message and composes a response to the first e-mail message. The response may be considered a second e-mail message. The second e-mail message may be considered to have at least two portions: an “old” portion, comprising the initial portion of the first e-mail message; and a “new” portion, comprising the content composed by the user of the mobile wireless device. The user of the mobile wireless device may decide to sign the second e-mail message. Accordingly, when obtaining a signature to associate with the second e-mail message, the mobile wireless device may only obtain a hash of the second e-mail message (i.e., the old portion appended to the new portion). That is, the mobile wireless device encrypts a hash of the second e-mail message with the private key stored at the mobile wireless device. The mobile mail server would normally append the remaining (i.e., non-initial) portion of the first e-mail message to the received second e-mail message to form a complete response, before forwarding the complete response to the origin of the first e-mail message. However, since the signature received in association with the second e-mail message only relates to the old portion appended to the new portion, and not to the complete response, the mobile mail server must simply forward the second e-mail message and associated signature toward the origin of the first e-mail message. 
     At the origin of the first e-mail message, the recipient of the second e-mail message does not receive all of the typically appended first e-mail message content and, accordingly, may struggle with the placing of the second e-mail message properly in context. 
     To provide awareness to the sender of the second e-mail message (i.e., the user of the mobile wireless device) that the second e-mail message will include only a truncated version of the first e-mail message, the mobile wireless device may display a warning dialog. The warning dialog may be displayed responsive to the user of the mobile wireless device indicating, using a user interface in a message composition mode, that the second e-mail message is to be sent. The warning dialog may indicate “Warning! Your message will be truncated.” Furthermore, the warning dialog may be interactive and may require user selection of a choice before the warning dialog may be dismissed from the display. That is, the warning dialog may present choices labeled “OK” and “Cancel”. Additionally, the warning dialog may include a checkbox labeled “Don&#39;t show this dialog again”. The user may select the “OK” choice to indicate acceptance of the truncation. Alternatively, the user may select the “Cancel” choice to indicate a wish to return to composing the message. By selecting the checkbox labeled “Don&#39;t show this dialog again” and then selecting the “OK” choice, the user may effectively set a policy for the mobile wireless device, where the policy indicates that all future signed, and/or encrypted, messages are to include only a truncated version of the original received message. 
     Upon receiving an indication that the user has selected the “OK” choice, the mobile wireless device may proceed to transmit the second e-mail message to the mobile mail server for forwarding to the sender of the first e-mail message. 
     Upon receiving an indication that the user has selected the “Cancel” choice, the mobile wireless device may return the user interface to the message composition mode. Responsive to being returned to the message composition mode, the user may manipulate the user interface to copy, to a clipboard, the message that has been typed (i.e., the new portion). The user may then close the message composition user interface, return to a message list and re-open the first message. Once the initial portion of the first message is open, the user may manipulate a message viewing user interface to request, from the mobile mail server, the entire first message. The user may then manipulate the message viewing user interface to indicate a wish to compose a response to the first message. Once the message composition user interface has been opened, pre-loaded with the entirety of the first e-mail message, the user may paste the previously composed new portion from the clipboard to the message composition area in the message composition user interface, thereby creating a third e-mail message. The third e-mail message may be distinguished from the second e-mail message in that the third e-mail message includes the entirety of the first e-mail message and the second e-mail message only includes a truncated version of the first e-mail message. The user may then create a signature for the third e-mail message and indicate that the third e-mail message and the signature are to be sent. 
     One can see that including an entire original message in a signed response can require manually carrying out some potentially tedious and complex steps. 
     By arranging assembly, at a server, of a composite message from a new message and an original message and arranging encryption and signing of the composite message in cooperation with a wireless messaging device, operational complexity on the part of the user can be obviated. 
     In an aspect of the present disclosure there is provided a method of processing an electronic message at a mobile wireless communication device. The method includes detecting receipt of an instruction to encrypt and transmit a composite message, where the composite message includes a new message and an original message, obtaining cryptographic information for use in carrying out the encryption request, transmitting the new message to a server associated with the mobile wireless communication device and transmitting an encryption request to the server, the encryption request including the cryptographic information and specifying the original message. In other aspects of the present application, a mobile wireless communication device is provided for carrying out this method and a computer readable medium is provided for adapting a processor to carry out this method. 
     In another aspect of the present disclosure there is provided a method of processing an electronic message. The method includes detecting receipt of a message processing request for encryption and transmission of a composite message, where the composite message includes a new message and an original message, the message processing request including the new message, an indication of the original message and cryptographic information for use in the encryption, creating the composite message from the new message and the original message, employing a first portion of the cryptographic information to encrypt the composite message to form an encrypted composite message and transmitting the encrypted composite message. In other aspects of the present application, a mail server is provided for carrying out this method and a computer readable medium is provided for adapting a processor to carry out this method. 
     Other aspects and features of the present application will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the application in conjunction with the accompanying figures. 
     Referring to  FIG. 1 , an overview of an example system for use with the embodiments described below is shown. One skilled in the art will appreciate that there may be many different topologies, but the system shown in  FIG. 1  helps demonstrate the operation of the systems and methods described in the present application. For example, there may be many mobile communication devices connected to the system that are not shown in the overview of  FIG. 1 . 
       FIG. 1  shows a mobile wireless device in the form of a mobile communication device  100 . It will be appreciated by those skilled in the art that the mobile communication device  100  may comprise any computing or communication device that is capable of connecting to a network by wireless means, including, but not limited, to personal computers (including tablet and laptop computers), personal digital assistants, smart phones, and the like. It will further be appreciated by those skilled in the art that these devices may be referred to herein as computing devices or communication devices, and may have principal functions directed to data or voice communication over a network, data storage or data processing, or the operation of personal or productivity applications; those skilled in the art will appreciate that terminology such as “mobile device”, “communication device”, “computing device”, or “user device” may be used interchangeably. 
     The mobile communication device  100  may, for example, be connected to an Internet Service Provider on which a user of the system of  FIG. 1 , likely the user associated with the mobile communication device  100  illustrated in  FIG. 1 , has an account. 
     The mobile communication device  100  may be capable of sending and receiving messages and other data via wireless transmission and reception, as is typically done using electromagnetic waves in the radio frequency (RF) spectrum. The exchange of messages and other data may occur, for instance, between the mobile communication device  100  and a base station in a wireless carrier network  106 . The mobile communication device  100  may receive data by other means, for example through a direct connection to a port provided on the mobile communication device  100 . An example of such a direct connection is a Universal Serial Bus (USB) link. 
     As illustrated in  FIG. 1 , the wireless carrier network  106  connects to a wide area network  114 , represented as the Internet, via a wireless infrastructure  110 . The wireless infrastructure  110  incorporates a wireless gateway  112  for connecting to the Internet  114 . 
     A connection between the mobile communication device  100  and the Internet  114  allows the mobile communication device  100  to access a wireless mail server  118 . The wireless mail server  118  may include a processor  117  and a memory  119 . The wireless mail server  118  may be grouped together with other servers (not shown) in an enterprise  120 . Also connected to the Internet  114  may be a representative message origin  130 . The mobile communication device  100  may store a private cryptographic key  124  that is associated with a corresponding public cryptographic key. 
       FIG. 2  illustrates the mobile communication device  100 . The mobile communication device  100  includes a housing, an input device (e.g., a keyboard  224  having a plurality of keys) and an output device (e.g., a display  226 ), which may be a full graphic, or full color, Liquid Crystal Display (LCD). In some embodiments, the display  226  may comprise a touchscreen display. In such embodiments, the keyboard  224  may comprise a virtual keyboard. Other types of output devices may alternatively be utilized. A processing device (a processor  228 ) is shown schematically in  FIG. 2  as coupled between the keyboard  224  and the display  226 . The processor  228  controls the operation of the display  226 , as well as the overall operation of the mobile communication device  100 , in part, responsive to actuation of the keys on the keyboard  224  by a user. Notably, the keyboard  224  may comprise physical buttons (keys) or, where the display  226  is a touchscreen device, the keyboard  224  may be implemented, at least in part, as “soft keys”. Actuation of a so-called soft key involves either touching the display  226  where the soft key is displayed or actuating a physical button in proximity to an indication, on the display  226 , of a temporary action associated with the physical button. 
     The housing may be elongated vertically, or may take on other sizes and shapes (including clamshell housing structures). Where the keyboard  224  includes keys that are associated with at least one alphabetic character and at least one numeric character, the keyboard  224  may include a mode selection key, or other hardware or software, for switching between alphabetic entry and numeric entry. 
     In addition to the processor  228 , other parts of the mobile communication device  100  are shown schematically in  FIG. 2 . These may include a communications subsystem  202 , a short-range communications subsystem  204 , the keyboard  224  and the display  226 . The mobile communication device  100  may further include other input/output devices, such as a set of auxiliary I/O devices  206 , a serial port  208 , a speaker  211  and a microphone  212 . The mobile communication device  100  may further include memory devices including a flash memory  216  and a Random Access Memory (RAM)  218  and various other device subsystems  220 . The mobile communication device  100  may comprise a two-way radio frequency (RF) communication device having voice and data communication capabilities. In addition, the mobile communication device  100  may have the capability to communicate with other computer systems via the Internet. 
     Operating system software executed by the processor  228  may be stored in a computer readable medium, such as the flash memory  216 , but may be stored in other types of memory devices, such as a read only memory (ROM) or similar storage element. In addition, system software, specific device applications, or parts thereof, may be temporarily loaded into a volatile store, such as the RAM  218 . Communication signals received by the mobile device may also be stored to the RAM  218 . 
     The processor  228 , in addition to its operating system functions, enables execution of software applications on the mobile communication device  100 . A predetermined set of software applications that control basic device operations, such as a voice communications module  230 A and a data communications module  230 B, may be installed on the mobile communication device  100  during manufacture. A message processing module  230 C may also be installed on the mobile communication device  100  during manufacture, to implement aspects of the present disclosure. As well, additional software modules, illustrated as an other software module  230 N, which may be, for instance, a PIM application, may be installed during manufacture. The PIM application may be capable of organizing and managing data items, such as e-mail messages, calendar events, voice mail messages, appointments and task items. The PIM application may also be capable of sending and receiving data items via a wireless carrier network  106  represented by a radio tower. The data items managed by the PIM application may be seamlessly integrated, synchronized and updated via the wireless carrier network  106  with the device user&#39;s corresponding data items stored or associated with a host computer system. 
     Communication functions, including data and voice communications, are performed through the communication subsystem  202  and, possibly, through the short-range communications subsystem  204 . The communication subsystem  202  includes a receiver  250 , a transmitter  252  and one or more antennas, illustrated as a receive antenna  254  and a transmit antenna  256 . In addition, the communication subsystem  202  also includes a processing module, such as a digital signal processor (DSP)  258 , and local oscillators (LOs)  260 . The specific design and implementation of the communication subsystem  202  is dependent upon the communication network in which the mobile communication device  100  is intended to operate. For example, the communication subsystem  202  of the mobile communication device  100  may be designed to operate with the Mobitex™, DataTAC™ or General Packet Radio Service (GPRS) mobile data communication networks and also designed to operate with any of a variety of voice communication networks, such as Advanced Mobile Phone Service (AMPS), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Personal Communications Service (PCS), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Wideband Code Division Multiple Access (W-CDMA), High Speed Packet Access (HSPA), etc. Other types of data and voice networks, both separate and integrated, may also be utilized with the mobile communication device  100 . 
     Network access requirements vary depending upon the type of communication system. Typically, an identifier is associated with each mobile device that uniquely identifies the mobile device or subscriber to which the mobile device has been assigned. The identifier is unique within a specific network or network technology. For example, in Mobitex™ networks, mobile devices are registered on the network using a Mobitex Access Number (MAN) associated with each device in DataTAC™ networks, mobile devices are registered on the network using a Logical Link Identifier (LLI) associated with each device. In GPRS networks, however, network access is associated with a subscriber or user of a device. A GPRS device therefore uses a subscriber identity module, commonly referred to as a Subscriber Identity Module (SIM) card, in order to operate on a GPRS network. Despite identifying a subscriber by SIM, mobile devices within GSM/GPRS networks are uniquely identified using an International Mobile Equipment Identity (IMEI) number. 
     When required network registration or activation procedures have been completed, the mobile communication device  100  may send and receive communication signals over the wireless carrier network  106 . Signals received from the wireless carrier network  106  by the receive antenna  254  are routed to the receiver  250 , which provides for signal amplification, frequency down conversion, filtering, channel selection, etc., and may also provide analog to digital conversion. Analog-to-digital conversion of the received signal allows the DSP  258  to perform more complex communication functions, such as demodulation and decoding. In a similar manner, signals to be transmitted to the wireless carrier network  106  are processed (e.g., modulated and encoded) by the DSP  258  and are then provided to the transmitter  252  for digital to analog conversion, frequency up conversion, filtering, amplification and transmission to the wireless carrier network  106  (or networks) via the transmit antenna  256 . 
     In addition to processing communication signals, the DSP  258  provides for control of the receiver  250  and the transmitter  252 . For example, gains applied to communication signals in the receiver  250  and the transmitter  252  may be adaptively controlled through automatic gain control algorithms implemented in the DSP  258 . 
     In a data communication mode, a received signal, such as a text message or web page download, is processed by the communication subsystem  202  and is input to the processor  228 . The received signal is then further processed by the processor  228  for output to the display  226 , or alternatively to some auxiliary I/O devices  206 . A device user may also compose data items, such as e-mail messages, using the keyboard  224  and/or some other auxiliary I/O device  206 , such as a touchpad, a rocker switch, a thumb-wheel, a trackball, a touchscreen, or some other type of input device. The composed data items may then be transmitted over the wireless carrier network  106  via the communication subsystem  202 . 
     In a voice communication mode, overall operation of the device is substantially similar to the data communication mode, except that received signals are output to the speaker  211 , and signals for transmission are generated by a microphone  212 . Alternative voice or audio I/O subsystems, such as a voice message recording subsystem, may also be implemented on the mobile communication device  100 . In addition, the display  226  may also be utilized in voice communication mode, for example, to display the identity of a calling party, the duration of a voice call, or other voice call related information. 
     The short-range communications subsystem  204  enables communication between the mobile communication device  100  and other proximate systems or devices, which need not necessarily be similar devices. For example, the short-range communications subsystem may include an infrared device and associated circuits and components, or a Bluetooth™ communication module to provide for communication with similarly-enabled systems and devices. 
     In overview, the mobile communication device  100  receives an initial portion of a first e-mail message from the wireless mail server  118 , where the first e-mail message has originated at the representative message origin  130 . The user of the mobile communication device  100  manipulates the mobile communication device  100  to invoke a message composition user interface preloaded with the received initial portion of the first e-mail message and composes a new portion. Where the user has specified that the message is to be processed (e.g., signed and/or encrypted), responsive to the user indicating that the message is to be sent, aspects of the present disclosure allow for the processing of a new message that includes the new portion and the entirety of the first e-mail message. 
     For example, the message composition user interface may allow the user to specify that the message is to be signed. Typically, when the user has indicated that the message is to be sent, the message composition user interface prompts the user for a password associated with a key store in which the private cryptographic key  124  is stored. Upon verifying a received password, the processor  228  executes a message signing algorithm to generate a signature by, first, generating a hash of the message and, second, encrypting the hash with the private cryptographic key  124 . 
     In a first cross-component message processing approach, some automation is provided to the complex operations. Responsive to the user indicating that a reply message with truncated original message is to be sent, it is proposed herein to prompt the user with a dialog that includes a user option to “Download Original”. Responsive to receiving an indication that the “Download Original” user option has been selected, the processor  228  may automatically download the remainder of the original message and append the remainder of the original message to the reply message. The processor  228  may then sign, encrypt or sign and encrypt the reply message with the entire original message before sending, thereby providing full, end-to-end security. 
     Steps of a method that is an example of a first cross-component message signing approach are presented in  FIG. 3 . Initially, the processor  228 , or, more accurately, a signature handling application executed on the processor  228 , detects receipt (step  302 ) of an instruction to transmit a response message and an associated signature. Such an instruction may be received from the message composition user interface application also executed on the processor  228 . 
     From the user&#39;s perspective, the user has specified that the response message is to be signed and the user has composed the new portion of the response message (in any order). The user may have configured the mobile communication device  100 , at some earlier time, to, by default, transmit an associated signature with each outgoing messages. The receipt (detected in step  302 ), by the signature handling application, of the instruction to transmit a response message and an associated signature may be triggered by the user opening a menu and selecting a “send” menu item. 
     Responsive to the detection in step  302 , the signature handling application may present (step  304 ) a dialog to warn the user that the first e-mail message will be incompletely included in the response message and giving the user choice regarding how or whether to proceed. An example of a suitable dialog is illustrated as a dialog  400  in  FIG. 4 . The dialog  400  is illustrated as being displayed on the display  226  of the mobile communication device  100 . 
     As has been discussed above, the dialog  400  may include choices labeled “OK” and “Cancel”. Furthermore, according to an aspect of the present disclosure, the dialog  400  may include another choice, labeled “Download Original”. 
     It is expected that the user of the mobile communication device  100  will interact with the dialog  400  to select one of the choices. Accordingly, the signature handling application may receive (step  306 ) an indication of the user selection and determine (step  308 ) which of the choices the user has selected. Upon determining (step  308 ) that the user has selected the “Cancel” choice, the signature handling application may return (step  310 ) control to the message composition user interface. 
     Upon determining (step  308 ) that the user has selected the “OK” choice, the signature handling application may generate (step  312 ) a signature for the response message. To distinguish this signature from an alternative signature to be discussed hereinafter, this signature may be termed a “response” signature. The response signature is a result of encrypting a hash of the response message, where the response message includes the new portion, recently composed by the user of the mobile communication device  100 , and the initial portion of the first e-mail message (i.e., not the entire first e-mail message). The signature handling application may then arrange the transmission (step  314 ) of the response message and the response signature. 
     Upon determining (step  308 ) that the user has selected the “Download Original” choice, the signature handling application may obtain (step  316 ) the remainder of the first e-mail message from the wireless mail server  118  and form (step  318 ) a “new” message. The new message may be formed from the new portion, recently composed by the user of the mobile communication device  100 , and the entirety of the first e-mail message, obtained in step  316 . The signature handling application may then generate (step  320 ) a signature for the new message. To distinguish this signature from the “response” signature, this signature may be termed a “new” signature. The new signature is a result of encrypting a hash of the new message. The signature handling application may then arrange the transmission (step  322 ) of the new message and the new signature. 
     Additionally, the warning dialog  400  may include a checkbox labeled “Always download original”. By selecting the checkbox labeled “Always download original” and then selecting the “Download Original” choice, the user may effectively set a policy for the mobile wireless device, where the policy indicates that all future signed, and/or encrypted, messages are to include the entirety of the original received message. 
     As a further alternative, the dialog  400  may include a checkbox labeled “Always send truncated” (not shown). By selecting the checkbox labeled “Always send truncated” (not shown) and then selecting the “OK” choice, the user may effectively set a policy for the mobile wireless device, where the policy indicates that all future signed, and/or encrypted, messages are to include only a truncated version of the original received message. 
     Apart from the dialog  400 , the user may be provided with an opportunity to establish a policy through editing a policy through use of a configuration options user interface. Such a configuration options user interface may allow the user to specify a size threshold for the original message so that an original message exceeding the size threshold is not automatically downloaded in its entirety for inclusion in the new message. 
     Notably, the automatic downloading of the original message may be accomplished on a background thread so that the user does not have to wait for the original message to be downloaded before carrying out further activities on the mobile communication device  100 . Responsive to indicating that the message is to be sent, the user may be prompted for a signing password, but the cryptographic key, for encrypting a hash of the new message, would not be used until after the original message has been downloaded. 
     Notably, the original message may not always be downloaded immediately. The mobile communication device  100  makes use of a data network connection to download the original message. Accordingly, in the absence of a data network connection, the mobile communication device  100  waits until a data network connection has been established, before downloading the original message. 
     The first cross-component message signing approach may be adapted for message encryption instead of, or in addition to, message signing. Steps of a method that is an example of adapting the first cross-component message signing approach to encryption are presented in  FIG. 5 . Initially, the processor  228 , or, more accurately, an encryption handling application executed on the processor  228 , detects receipt (step  502 ) of an instruction to transmit an encrypted response message. Such an instruction may be received from the message composition user interface application also executed on the processor  228 . 
     From the user&#39;s perspective, the user has specified that the response message is to be encrypted and the user has composed the new portion of the response message (in any order). The user may have configured the mobile communication device  100 , at some earlier time, to, by default, encrypt each outgoing messages. The receipt (detected in step  502 ), by the encryption handling application, of the instruction to transmit an encrypted version of the response message may be triggered by the user opening a menu and selecting a “send” menu item. 
     Responsive to the detection in step  502 , the encryption handling application may present (step  504 ) a dialog to warn the user that the first e-mail message will be incompletely included in the response message and giving the user choice regarding how or whether to proceed. An example of a suitable dialog is illustrated as a dialog  400  in  FIG. 4 . The dialog  400  is illustrated as being displayed on the display  226  of the mobile communication device  100 . 
     As has been discussed above, the dialog  400  may include choices labeled “OK” and “Cancel”. Furthermore, the dialog  400  may include another choice, labeled “Download Original”. 
     It is expected that the user of the mobile communication device  100  will interact with the dialog  400  to select one of the choices. Accordingly, the encryption handling application may receive (step  506 ) an indication of the user selection and determine (step  508 ) which of the choices the user has selected. Upon determining (step  508 ) that the user has selected the “Cancel” choice, the encryption handling application may return (step  510 ) control to the message composition user interface. 
     Upon determining (step  508 ) that the user has selected the “OK” choice, the encryption handling application may encrypt (step  512 ) the response message. The encryption handling application may then arrange the transmission (step  514 ) of the encrypted response message. 
     Upon determining (step  508 ) that the user has selected the “Download Original” choice, the encryption handling application may obtain (step  516 ) the remainder of the first e-mail message from the wireless mail server  118  and form (step  518 ) a “new” message. The new message may be formed from the new portion, recently composed by the user of the mobile communication device  100 , and the entirety of the first e-mail message, obtained in step  516 . The encryption handling application may then encrypt (step  520 ) the new message. The encryption handling application may then arrange the transmission (step  522 ) of the encrypted new message. 
     A second cross-component message signing approach involves splitting the signing operation between the mobile communication device  100  and the wireless mail server  118 , thereby avoiding the downloading of the original message. Unlike the first approach, this split-signing approach cannot be considered to result in true end-to-end security, because the entire e-mail message is not signed strictly at the mobile communication device  100 . Rather, at least the new portion, recently composed by the user of the mobile communication device  100 , is signed strictly at the device, and the signing of the entire message, including the remainder not signed strictly at the device, involves the wireless mail server  118 . However, this second approach does provide a compromise between security and use of wireless channel resources, which makes it particularly suitable for signing large messages or messages with large attachments. 
     Steps of a method that is an example of the second approach are presented in  FIG. 6 . Initially, the signature handling application detects receipt (step  602 ) of an instruction to transmit a response message and an associated signature. Such an instruction may be received from the message composition user interface application also executed on the processor  228 . 
     Responsive to the detection in step  602 , the signature handling application may automatically add (step  603 ) a disclaimer to the end of the response message, indicating that this point in the message marks the end of the part of the message signed at the mobile communication device  100  and/or the beginning of the part signed with the assistance of the wireless mail server  118 . For example, the disclaimer may be a line of text, such as “—end of device-signed data—”. The signature handling application may further obtain (step  604 ) a hash of the response message, where the response message includes the new portion, recently composed by the user of the mobile communication device  100 , and the initial portion of the first e-mail message (i.e., not the entire first e-mail message). 
     The signature handling application may then arrange the transmission (step  606 ), to the wireless mail server  118 , of a request that the wireless mail server  118  continue the hashing across the first e-mail message. Along with the request, the signature handling application may arrange the transmission of the “context” of the hash of the response message to the wireless mail server  118 . The context may be an indication of the internal state of the hashing algorithm. Such an internal state indication may allow the wireless mail server  118  to continue to obtain the hash. 
     Steps in an example method of participating, at the wireless mail server  118 , in the split signing operation are illustrated in  FIG. 7 . Initially, the wireless mail server  118  receives (step  702 ) the hash continuation request. The wireless mail server  118  has awareness of the portion of the first e-mail message that was transmitted to the mobile communication device  100  and can therefore generate (step  704 ) a “final” hash by hashing the portion of the first e-mail message that has not been transmitted to the mobile communication device  100 , where the final hash is a hash of a “new” message. The new message includes the new portion, recently composed by the user of the mobile communication device  100 , and the entirety of the first e-mail message. 
     Alternatively, if the hashing algorithm is a “streaming” algorithm, the mobile communication device  100  may transmit, to the wireless mail server  118 , the current value of the hash. 
     Upon completing generation (step  704 ) of the hash across the first e-mail message, the wireless mail server  118  transmits (step  706 ) the final hash to the mobile communication device  100 . It should be clear that the final hash is likely to be significantly smaller than the remainder of the original message. 
     Upon receiving (step  608 ) the final hash from the wireless mail server  118 , the mobile communication device  100  signs (step  610 ) the final hash and arranges (step  612 ) the transmission of the response message and the encrypted hash to the wireless mail server  118 . The encrypted hash may be called the new signature. 
     Upon receiving (step  708 ) the response message and the new signature, the wireless mail server  118  constructs the new message by appending (step  710 ) the portion of the first e-mail message that has not been transmitted to the mobile communication device  100  to the response message and transmits (step  712 ) the new message and the new signature. 
     Since the second cross-component message signing approach represented by the methods of  FIGS. 6 and 7  may not be considered to result in true, end-to-end security, the user may be provided with an opportunity to select the second cross-component message signing approach on a per-message basis, depending on the size of the data and/or security requirements. 
     In a third cross-component message signing approach, the entire hash is generated on the wireless mail server  118 . The user composes the new portion and indicates that the response message and an associated signature are to be sent. 
     Steps of a method that is an example of the third cross-component message signing approach are presented in  FIG. 8 . Initially, the signature handling application at the mobile communication device  100  detects receipt (step  802 ) of an instruction to transmit the response message and the associated signature. 
     Responsive to the detection in step  802 , the signature handling application may arrange (step  804 ) transmission of the new portion to the wireless mail server  118 . 
     Steps in an example method of participating, at the wireless mail server  118 , in the third cross-component message signing approach are illustrated in  FIG. 9 . Initially, the wireless mail server  118  receives (step  902 ) the new portion and appends the first e-mail message to the new portion, thereby forming (step  904 ) the new message. The wireless mail server  118  then generates (step  906 ) a hash of the new message. The wireless mail server  118  transmits (step  908 ) the hash to the mobile communication device  100 . 
     At the mobile communication device  100 , the signature handling application receives (step  806 ) the hash and signs (step  808 ) the hash to generate the new signature. The signature handling application then arranges (step  810 ) the transmission of the new signature to the wireless mail server  118 . 
     Upon receipt (step  910 ) of the new signature, the wireless mail server  118  transmits (step  912 ) the new message and the new signature. 
     The second approach to cross-component message signing exemplified in the combination of  FIGS. 6 and 7  and the third approach to cross-component message signing exemplified in the combination of  FIGS. 8 and 9  are suitable for message signing, but differences in the manner in which a message is signed and the manner in which a message is encrypted lead to a lack of direct applicability of these approaches to the encryption of a message. 
     In overview, the disclosed approaches for message signing may, with some adaptation, be extended for use in message encryption. In part, the adaptation involves the mobile communication device  100  transmitting additional, special cryptographic information to the wireless mail server  118 , thereby allowing the wireless mail server  118  to encrypt a given message. 
       FIG. 10  illustrates example steps of a cross-component message encryption approach. Initially, a message processing application executed on the processor  228  detects receipt (step  1002 ) of an instruction to transmit an encrypted message. Such an instruction may be received from the message composition user interface application also executed on the processor  228 . 
     As discussed hereinbefore, where the message to be encrypted is a message that is formed from a new portion and an initial portion of an original message, the user of the mobile communication device  100  may prefer that the entirety of the original message be included as context for the new portion. However, as also discussed hereinbefore, only the initial portion of the original message may be present at the mobile communication device  100 . Furthermore, it is noted that the original message may have been encrypted. 
     Responsive to detecting receipt (step  1002 ) of the instruction, the processor  228 , under control of the message processing application, may then obtain (step  1004 ) the cryptographic information that the processor  228  would typically use to encrypt a message. Such cryptographic information may include, for example, one or more session keys, including a composite message session key for encrypting the composite message, along with one or more initialization vectors corresponding to each of the one or more session keys. An initialization vector is a block of bits that allows a stream cipher or a block cipher to be executed in any of several modes of operation to produce a unique stream independent from other streams produced by the same session key. Where the original message was encrypted, the cryptographic information may also include one or more session keys, such as an original message session key for decrypting the original message. 
     The processor  228 , under control of the message processing application, may then arrange the transmission (step  1006 ), to the wireless mail server  118 , of the message whose transmission was requested in step  1002 . The message processing application may include, in the transmission, a request for the formation and encryption of a composite message along with the cryptographic information obtained in step  1004 . 
       FIG. 11  illustrates example steps in a method of participating, at the wireless mail server  118 , in the cross-component message encryption approach of  FIG. 10 . Initially, the wireless mail server  118  receives (step  1102 ) the new message, encryption request and associated cryptographic information. 
     In the case wherein the original message was encrypted, the wireless mail server  118  may then decrypt (step  1104 ) the original message using an appropriate portion of the received cryptographic information. 
     The wireless mail server  118  may then create (step  1106 ) a composite message by appending the original message to the new message. Both the new message and the original message may include a body portion and one or more attachments. Accordingly, while creating (step  1106 ) the composite message, the wireless mail server  118  may append a body portion of the original message to a body portion of the new message and add attachments from the new message to the composite message and add attachments from the original message to the composite message. 
     Upon completing creation (step  1106 ) of the composite message, the wireless mail server  118  encrypts (step  1108 ) the composite message using an appropriate portion of the cryptographic information received in step  1102 . In conjunction with encrypting (step  1108 ) the composite message, the wireless mail server  118  may wrap the composite message in an appropriate encoding. Such appropriate encoding may, for example, comprise encoding using a standard known as Secure/Multipurpose Internet Mail Extensions (S/MIME), which is a known standard for public key encryption and signing of data. Alternatively, such appropriate encoding may, for example, comprise encoding using a standard known as Pretty Good Privacy (PGP), which is a known data encryption and decryption computer standard that provides cryptographic privacy and authentication for data communication. 
     In an alternate implementation, rather than receiving the composite message session key from the mobile communication device  100 , the wireless mail server  118  generates the composite message session key and the corresponding initialization vector. This implementation may also involve sending the composite message session key to the mobile communication device  100 , so that the mobile communication device  100  may decrypt the sent composite message, if necessary. 
     When the composite message has been encrypted and wrapped, the wireless mail server  118  may transmit (step  1110 ) the encrypted composite message toward recipients specified in a destination field of the new message. 
       FIG. 12  illustrates example steps of a cross-component message encryption approach distinct from the cross-component message encryption approach of  FIGS. 10 and 11 . Initially, a message processing application executed on the processor  228  detects receipt (step  1202 ) of an instruction to transmit an encrypted and signed message. Such an instruction may be received from the message composition user interface application also executed on the processor  228 . 
     As discussed hereinbefore, where the message to be encrypted and signed is a message that is formed from a new portion and an initial portion of an original message, the user of the mobile communication device  100  may prefer that the entirety of the original message be included as context for the new portion. However, as also discussed hereinbefore, often only the initial portion of the original message may be present at the mobile communication device  100 . Furthermore, it is noted that the original message may have been encrypted. 
     Responsive to detecting (step  1202 ) receipt of the instruction, the processor  228 , under control of the message processing application, may then obtain (step  1204 ) the cryptographic information that the processor  228  would typically use to encrypt a message. Such cryptographic information may include, for example, one or more session keys, including a composite message session key for encrypting the composite message, along with one or more initialization vectors corresponding to each of the one or more session keys. Where the original message was encrypted, the cryptographic information may also include one or more session keys, including an original message session key for decrypting the original message. 
     The processor  228 , under control of the message processing application, may then arrange the transmission (step  1206 ), to the wireless mail server  118 , of the message whose transmission was requested in step  1002 . The message processing application may include, in the transmission, the cryptographic information obtained in step  1004  and a request for a hash of the composite message to be created, at the wireless mail server  118 , from the new message and the original message. 
       FIG. 13  illustrates example steps in a method of participating, at the wireless mail server  118 , in the cross-component message encryption approach of  FIG. 12 . Initially, the wireless mail server  118  receives (step  1302 ) the new message, associated cryptographic information and hash request. 
     In the case wherein the original message was encrypted, the wireless mail server  118  may then decrypt (step  1304 ) the original message using an appropriate portion of the received cryptographic information. 
     The wireless mail server  118  may then create (step  1306 ) a composite message by appending the original message to the new message. Both the new message and the original message may include a body portion and one or more attachments. Accordingly, while creating (step  1306 ) the composite message, the wireless mail server  118  may append a body portion of the original message to a body portion of the new message and add attachments from the new message to the composite message and add attachments from the original message to the composite message. 
     Upon completing creation (step  1306 ) of the composite message, the wireless mail server  118  generates (step  1308 ) a hash of the composite message and transmits (step  1310 ) the hash to the mobile communication device  100  with a hash signing request, specifying that the hash is to be signed. 
     Upon receiving (step  1208 ) the hash signing request from the wireless mail server  118 , the mobile communication device  100  obtains (step  1210 ) a private key specific to a user of the mobile communication device  100 . Obtaining (step  1210 ) the private key may, for example, involve prompting the user for a password to allow the processor  228  access to a key store, in memory of the mobile communication device  100 , from which the processor  228  may obtain the private key. 
     Upon obtaining (step  1210 ) the private key, the processor  228  may sign (step  1212 ) the hash to form a signature for the composite message. The processor  228  may then arrange (step  1214 ) the transmission of the signature to the wireless mail server  118 . 
     The wireless mail server  118  receives (step  1312 ) the signature and adds (step  1314 ) the signature to the composite message. 
     Upon adding (step  1314 ) the signature to the composite message, the wireless mail server  118  may encrypt (step  1316 ) the signed composite message using an appropriate portion of the cryptographic information received in step  1302 . In conjunction with encrypting (step  1316 ) the signed composite message, the wireless mail server  118  may wrap the composite message in an appropriate encoding as discussed hereinbefore. 
     When the signed composite message has been encrypted and wrapped, the wireless mail server  118  may transmit (step  1318 ) the encrypted and signed composite message toward recipients specified in a destination field of the new message. 
     The above-described embodiments of the present application are intended to be examples only. Alterations, modifications and variations may be effected to the particular embodiments by those skilled in the art without departing from the scope of the application, which is defined by the claims appended hereto.

Technology Classification (CPC): 7