WO2008040996A2

WO2008040996A2 - Personal electronic device security

Info

Publication number: WO2008040996A2
Application number: PCT/GB2007/003789
Authority: WO
Inventors: Neil Millar Stewart; Steven Mark Harkins
Original assignee: Helixion Limited
Priority date: 2006-10-05
Filing date: 2007-10-05
Publication date: 2008-04-10
Also published as: EP2092453A2; GB0619696D0; WO2008040996A3

Abstract

A personal electronic device comprising: a first microprocessor which controls the personal electronic device; secure memory which stores (i) first secure data which is required for a security-related function of the personal electronic device to be carried out, and (ii) second secure data which is required for an authentication procedure; a second microprocessor which is communication with the first microprocessor and the secure memory and which controls access to the data stored in the secure memory; wherein the personal electronic device is not operable to carry out the security- related function which requires the first secure data until an authentication procedure which requires the second secure data has been successfully completed.

Description

Personal Electronic Device Security

Field of the Invention

The present invention relates to the field of personal electronic device security.

Background to the Invention

Personal electronic devices which are generally carried on the person of a user (such as personal digital assistants (PDAs), mobile telephones, music players etc.) are in common use at the present time. There are a number of applications, such as electronic messaging, banking and financial transactions etc., where it is desirable to provide the secure transmission of information to and from a personal electronic device or to ensure that the use of information stored on a personal electronic device is restricted.

Many such personal electronic devices comprise wireless communications interfaces. Examples include mobile telephones and personal digital assistants (PDAs) which comprise mobile telephone interfaces, such as GSM, GPRS, W-CDMA or UMTA interfaces. Personal electronic devices which comprise mobile telephone interfaces typically comprise an authentication token, such as a subscriber identification module (SIM) card, which stores data used to authenticate a subscriber with a mobile telephone network operator. The authentication procedure used to create a connection between a personal electronic device and a network operator includes security measures to enable the secure creation of a bearer service. However, these security measures do not in themselves provide for the secure processing and communication of data by an application executed on the personal electronic device. Even if data is securely transmitted to a personal electronic device, it remains vulnerable unless it can be ensured that only authorised personnel can view and/or work with that data.

It is known for mobile telephone network operators to exert control over the functionality of personal electronic devices. For example, personal electronic devices including a SIM card may be password protected and will not carry out specific functionality (e.g. make telephone calls or allow the display of stored messages) until a personal identification number (PIN) has been input. Some embodiments of the invention aim to provide improved authentication technology which is required before a security-related function of a personal electronic device can be carried out. Some embodiments aim to allow service providers other than mobile network operators (MNOs) to control aspects of the functionality of personal electronic devices.

Some embodiments of the present invention aim to provide improved security measures to protect electronic messages received by a personal electronic device or, in some embodiments, created by a personal electronic device.

Some embodiments of the present invention aim to facilitate the creation of a secure context between a software application executed on a personal electronic device and a remote server.

Summary of the Invention

According to a first aspect of the present invention there is provided a personal electronic device comprising:

a first microprocessor which controls the personal electronic device;

secure memory which stores (i) first secure data which is required for a security-related function of the personal electronic device to be carried out, and (ii) second secure data which is required for an authentication procedure; a second microprocessor which is in communication with the first microprocessor and the secure memory and which controls access to the data stored in the secure memory;

wherein the personal electronic device is not operable to carry out the security-related function which requires the first secure data until an authentication procedure which requires the second secure data has been successfully completed.

Thus, because the second microprocessor controls access to the data stored in the secure memory, which comprises the first and second secure data, the second microprocessor controls whether the personal electronic device is operable to carry out the security-related function.

Preferably, the second microprocessor and the secure memory is part of a removable memory device which is in removable electronic communication with the first microprocessor through an interface of the personal electronic device. Thus, a security-related function of the personal electronic device requires (i) the removable memory device to be present and (ii) an authentication procedure, which requires the second secure data, to have been completed.

The secure memory preferably comprises an integrated section of memory, which is integrated with the second microprocessor. The integrated section of memory may be integrated within the second microprocessor. The first secure data and/or the second secure data are preferably stored in the integrated section of memory.

The secure memory may comprise a section of memory which is readable on demand by the first microprocessor, but in which the data is encrypted, wherein decryption of the data requires data stored in the integrated section of memory. Data stored in the section of memory which is readable on demand may be decrypted by the second microprocessor using a decryption key stored in the integrated section of memory or generated in the integrated section of memory using the first secure data. Data stored in the section of memory which is readable on demand may be decrypted by the first microprocessor using a decryption key which is generated by the second microprocessor using data stored in the integrated section of memory. Typically, the encrypted data will have been encrypted by the second microprocessor or by the first microprocessor under the control of the second microprocessor. The removable memory device may comprise a removable non-volatile solid-state memory device, comprising a section of memory which is readable on demand, the second microprocessor and the integrated section of memory, whereupon the secure memory comprises the integrated section of memory and optionally a portion of the section of memory which is readable on demand, but in which the data is encrypted, wherein decryption of the data requires data stored in the integrated section of memory. The portion of the section of memory which is readable on demand which functions as secure memory may not be fixed, but may vary in use.

The second microprocessor and the secure memory may be integrated into a single semiconductor device to provide security. Because the second microprocessor controls access to data stored in the secure memory, the first microprocessor cannot obtain the data stored in the secure memory except under the control of the second microprocessor, for example because the second microprocessor has output the data to the first microprocessor or because the data has been decrypted under the control of the second microprocessor. Decryption under the control of the second microprocessor may be carried out by the second microprocessor with reference to the first secure data. Alternatively, or as well, decryption under the control of the second microprocessor may be carried out by the first microprocessor using data, (such as a decryption key derived from the first secure data), received from the second microprocessor with reference to the first secure data.

The removable memory device is preferably a non-volatile solid state memory device comprising the second microprocessor and the secure memory. Typically, the removable non-volatile solid state memory device will be adapted to resist access to the secure memory (except under the control of the second microprocessor).

Typically, the removable non-volatile solid state memory device will be a tamper- resistant silicon device. Preferably, the removable non-volatile solid state memory device comprises a section of memory which can be read on demand and preferably the removable memory device interfaces with a memory card interface (e.g. a memory card slot) of the personal electronic device. Part of the section of memory which can be read on demand may be used as secure memory.

The removable non-volatile solid state memory device is preferably a secure media card. For example, the secure media card may be a card according to the ISO/IEC O

7816 specification, a Secure Digital (SD), miniSD or microSD memory cards according to standards published by the SD Association (www.sdcard.org) or a SecureMMC cards according to standards published by the MultiMediaCard Association (www.mmca.org). (SD is a trade mark of Toshiba Corporation, miniSD is a trademark of SD association, microSD is a trade mark of SanDisk Corporation, SecureMMC is a trade mark of the MultiMediaCard Association). Within this specification, the term "secure media card" includes cards according to each of these formats.

Thus, in a preferred embodiment, the personal electronic device comprises a secure media card connected to a memory card interface (e.g. a memory card slot) of the personal electronic device, wherein the second microprocessor and the secure memory are part of the secure media card. The secure memory preferably comprises an integrated section of memory which is integrated with the second microprocessor. Secure media cards generally comprise memory which is readable on demand, part of which may be used as part of the secure memory.

The removable non-volatile solid-state memory device preferably does not comprise moving parts. The removable non-volatile solid-state memory device preferably does not comprise a battery. The second microprocessor and secure memory are typically integrated into a single microcontroller.

Alternatively, the non-volatile solid state memory device may be integrated with the first microprocessor. For example, the first microprocessor, the second microprocessor and the secure memory may all be integrated into a single semiconductor device.

The authentication procedure may comprise providing an identifier to a remote server, wherein the identifier is, or is derived from, the second secure data. The personal electronic device preferably comprises a wireless communications interface and the identifier may be provided to a remote server through the wireless communications interface.

The authentication procedure may comprise exchanging information with a remote server, preferably using the wireless communications interface. The second secure data may be used for authentication of the personal electronic device, a user of the personal electronic device, or a component of the personal electronic device (such as the removable memory device) with a remote server. The second secure data may be used to determine the response to a challenge from the remote server. The second secure data may comprise a key used to encrypt or decrypt data sent to or received from the remote server during the authentication procedure.

The personal electronic device may comprise an input module for receiving an identifier, the second secure data may comprise identity verification data, and the authentication procedure may be an identity verification procedure which verifies an identity using the received identifier and the identity verification data. The input module may comprise program code executed by the first microprocessor.

The input module may comprise an input device for inputting an identifier received from a user of the personal electronic device. The identifier input by a user may comprise a password and/or personal identification number (PIN). The input device may comprise a keyboard and/or touch screen. The input device may comprise a biometric data reader, such as an iris reader or fingerprint reader, and the input identifier may comprise biometric data. Typically, the input identifier will be transmitted to the second microprocessor by the first microprocessor and compared with the identity verification data.

The step of activation may require a user to input a one-time identifier, such as a one- time password or code which is verified with reference to one-off identity verification data (typically stored in the secure memory) and which only causes the first microprocessor to be operable to cause an electronic message to be decrypted and output using the output means on only one occasion. The personal electronic device may enable a user to input an identifier which is stored as identity verification data, or which can be used to calculate and store identity verification data, responsive to the input by a user of a one-time identifier. Thus, a one-time identifier might be sent to a user, e.g. by mail, to enable them to authenticate themselves, set their own password or input their own biometric details.

The authentication procedure may be carried out by the second microprocessor. The authentication procedure may comprise the step of comparing the received identifier and the identity verification data, although one skilled in the art will recognise that authentication with reference to identification data may be carried out in different ways, for example, the identity verification data may be a hash derived from the anticipated received identifier. The input module may be operable to receive a identifier from a device which is connected to the personal electronic device, for example, a unique identifier of a microprocessor or memory storage device which is integrated into the personal electronic device. However, the input module is preferably operable to receive an identifier from a device which is removably connected to the personal electronic device. For example, the input module may be operable to receive an identifier from an authentication token, such as a SIM card. For example, the identifier may be an Integrated Circuit Card Identifier (ICCID), international mobile subscriber identity (IMSI) or Mobile Station International ISDN Number (MSISDN) which is typically stored in a SIM card removably connected to the personal electronic device.

Preferably, device control program code is loaded from the removable memory device into memory which is integral to the personal electronic device and executed by the first microprocessor, and the device control program code manages communication between the first microprocessor and each of the removable memory device and the SIM card.

The security-related function which requires the first secure data may be the creation of a secure context between a software application executed on the personal electronic device (typically on the first microprocessor) and a remote server. That is to say, the first secure data may be used in the operation of a service for securely communicating data from the software application to the remote server and/or vice versa. Thus, because the first secure data is stored in the secure memory which is under the control of the second microprocessor, the second microprocessor can regulate the creation of a secure context between a software application executed on the personal electronic device and a remote server.

For example, the first secure data may comprise a key used for encrypting data which has been processed by the software application or selected by the software application for transmission to the remote server. The first secure data may comprise a key used for decrypting data received from the remote server and intended for secure relay to the software application. The first secure data may comprise shared secret data shared with the remote server for securely relaying data from the personal electronic device to the remote server and/or from the remote server to the personal electronic device. The first secure data may comprise authentication data used to authenticate with the remote server in order to create a secure context. The first secure data may be used by the second microprocessor to carry out one or more of the abovementioned functions. The first secure data may be used by the second microprocessor to prepare data for transmission to the first microprocessor, which carries out one or more of the abovementioned functions.

The security-related function which requires the first secure data may be the activation of a secure token (such as a SIM card) which has an authentication role in the creation of a wireless communications link (such as a mobile telephone network connection) using the first secure data.

For example, the security-related function may comprise the provision to a secure token of an identifier which is required before the secure token will fulfil its authentication role in the creation of a wireless communications link. Where the secure token is a mobile telephone SIM card, the identifier may be the SIM PIN required before the SIM can be used to connect to a mobile telephone network and/or before some data stored on the SIM can be accessed. The SIM card may be instructed to require a PIN provided by the personal electronic device. The identifier may be the personal unblocking key (PUK) of a SIM.

Thus, the first secure data may comprise the identifier (such as the PIN and/or PUK) of a SIM card.

The security-related function may include the step of changing the identifier required by the secure token and storing the new identifier (or data which can be used to generate the new identifier) as the first secure data. For example, the security- related function may comprise the step of changing the PIN required by a SIM card, and preferably also the step of storing the revised PIN as revised first secure data. The revised PIN will preferably be generated by the second microprocessor. As the revised PIN is generated by the second microprocessor and stored as first secure data, the user should not know the PIN and not be able to activate the SIM card without first having carried out the authentication procedure.

Where the secure memory is part of a removable memory device which is in removable electronic communication with the first microprocessor through an interface of the personal electronic device, the personal electronic device may be operable to change or reset the identifier required by the secure token (e.g. the PIN of the SIM). Where the secure memory is part of a removable memory device which is in removable electronic communication with the first microprocessor through an interface of the personal electronic device, the personal electronic device may be operable to cause a SIM card to require a PIN before it can be used to further communicate using a wireless communications link which requires the SIM card for authentication. This may be achieved by the first microprocessor (typically when executing program code which was loaded from the removable memory device) detecting that the removable memory device has been removed and then resetting a part of the electronic device comprising the SIM card, for example resetting a mobile telecommunication transceiver, such as a GSM module. For example this can be achieved on a Windows Mobile 5.0 device via a standard TAPI call as shown in the following line of code:

hres = NneSetEquipmentState( hLine, LINEEQU IPMENTSTATE_NOTXRX) ;

The personal electronic device may be adapted to block further authentication attempts and/or delete stored data (such as encrypted electronic messages) responsive to a user making more than a predetermined numbered of authentication attempts or responsive to a lock-down message received from a remote server, or the passage of a pre-determined period of time without user activity. Typically, the blocking of further authentication attempts and/or deletion of stored data takes place under the control of the second microprocessor.

The security-related function of the personal electronic device may be execution of program code by the first microprocessor, which program code comprises a software application which handles confidential data and which is initially stored in an encrypted form on a removable memory device, wherein the first secure data comprises a decryption key or other data required for the decryption of the stored program code. Decryption of the stored program code may be carried out by the second microprocessor with reference to the first secure data, or by the first microprocessor using data received from the second microprocessor with reference to the first secure data. The personal electronic device may further comprise:

a message receiving module for receiving encrypted electronic messages,

a message communication module for communicating a decrypted electronic message which was received in encrypted form by the message receiving module;

an output control module which is operable, following the completion of the authentication procedure, to cause at least part of an encrypted electronic message which has been received by the message receiving module, to be decrypted and communicated by the message communication module;

wherein the output control module is not operable to cause an encrypted electronic message to be decrypted and communicated using the message communication module prior to completion of the authentication procedure, but is operable to cause an encrypted electronic message to be decrypted and communicated using the message communication module once the authentication procedure has been completed;

wherein the first secure data is required for the decryption of a received electronic message and the security-related function comprises the decryption of a received electronic message.

The message receiving module may comprise a wireless communications receiver (which will typically be part of a wireless communications transceiver).

The message communication module may comprise an output device, such as a display, for displaying an electronic message which has been decrypted. The output device may comprise audio output means, such as a loudspeaker, for providing audio output of an electronic message which has been decrypted.

The message communication module may comprise a functional part of a software application which is executed on the first microprocessor in use and which outputs the decrypted electronic message to another software application which is executed on the first microprocessor. Thus, an electronic message may be securely communicated from a remote device (e.g. a server) which encrypted the electronic message to a software application executed on the first microprocessor. The decrypted electronic message may be output by relaying a pointer or handle to the decrypted electronic message to the other software application.

Although the received encrypted electronic message will have been decrypted before it is communicated by the message communication module using a decryption procedure which was dependent on the first secure data, the message communication module may communicate the decrypted electronic message in an encrypted format. For example, the electronic message may have been encrypted using more than one layer of encryption and only one layer of encryption may have been decrypted. The decrypted electronic message may have been reencrypted using a different encryption algorithm or key to that used to encrypt the received encrypted electronic message before it was transmitted to and received by the personal electronic device.

Preferably, the message communication module comprises program code which is loaded from the removable memory device into memory which is integral to the personal electronic device in use and executed by the first microprocessor.

The output control module typically comprises a functional part of a software application executed on the first microprocessor or the second microprocessor which causes the second microprocessor to decrypt an electronic message. The output control module and the message communication module may be part of the same software application.

The whole encrypted electronic message may be decrypted and output, however only part of the encrypted electronic message may be decrypted and output. The encrypted electronic message may be received in combination with non-encrypted data.

Preferably, the first secure data comprises a decryption key or secret data. The step of decrypting an encrypted electronic message (or at least part thereof) may be carried out by the second microprocessor. However, the decryption of an encrypted electronic message (or at least part thereof) may be carried out other than by the second microprocessor (e.g. by the first microprocessor) by a procedure which nevertheless requires the first secure data. For example, the encrypted electronic message (or at least a part thereof) may be decrypted by the first microprocessor using a key derived from the first secure data by the second microprocessor.

Preferably, the decryption key or secret data is sufficient to enable decryption of the electronic message (or at least part thereof). Preferably, the decryption key or secret data enables the electronic message (or at least part thereof) to be decrypted without communication with a remote device, such as a server which encrypted the electronic message.

Thus, because the first secure data is required for decryption of the received electronic messages (or at least parts thereof) and access to the secure memory is controlled by the second microprocessor, electronic messages can be relayed in encrypted form from a remote server which encrypted the electronic messages to the personal electronic device such that decryption is under the control of the second microprocessor (whether or not the actual decryption is carried out by the second microprocessor). This provides an important security benefit where the electronic message is transmitted through unsecure communication means, or communication means owned by an untrusted party, or where the personal electronic device comprises software applications which are executable by the first microprocessor and are not trusted. A secure context can thereby be created between the server which encrypts the electronic messages and the second microprocessor which controls decryption with reference to the first secure data.

Thus, the received encrypted electronic messages are preferably stored such that they can only be decrypted under the control of the second microprocessor, with reference to the first secure data.

A decryption key may be part of a key pair, wherein the other key in the key pair was previously transmitted from the second microprocessor to a server which used the other key in the key pair to encrypt the electronic message which is received as an encrypted electronic message. Keys in a key pair may be asymmetric keys or symmetric keys, and so they may be the same as each other.

The first secure data may comprise a shared secret, which corresponds with data stored securely in server means, wherein the second microprocessor and the server means uses the shared secret to securely transmit an encrypted electronic message from the server means to the personal electronic device via a communications link. The secure memory may store a secret key which can be used to decrypt a received encrypted electronic message which has been encrypted (for example, by server means) using a public key which is complementary to the secret key. Public key cryptosystems, such as the RSA algorithm, are well-known to those skilled in the art.

Typically, the electronic messages (or at least parts thereof) will be decrypted by the second microprocessor and the electronic message (or at least a part thereof) will be relayed from the second microprocessor to the first microprocessor for the first microprocessor to cause the electronic message to be output using the output means in a format which is unencrypted (for example, plain text) or encrypted using a different encryption method and/or key (stored in memory which is directly accessible to the first microprocessor) to that used to encrypt the electronic message when it was received.

However, the encrypted electronic messages (or at least part thereof) may be decrypted by the first microprocessor by a procedure which requires the first secure data, for example by a decryption procedure using a one-off decryption key provided by the second microprocessor using a key or data stored in the secure memory as first secure data.

The electronic messages may comprise information to be communicated to the user of the personal electronic device. The said information is preferably information of a type which is generally communicated to a user through an output device. The electronic messages may comprise data to be communicated to a software application which is executed on the personal electronic device (this is especially relevant where the message communication module outputs the decrypted electronic message to a software application). The electronic messages may comprise electronic documents, such as word-processor documents, spreadsheet documents, graphics software documents, or other application records which are used by software applications.

The electronic messages may communicate data to an application which is executed on the personal electronic device, the functionality of which is restricted until the authentication procedure which requires the second secure data has been successfully completed. The electronic messages may comprise visual information which is suitable for display on a display. The electronic messages may comprise audio information which is suitable for output through a loudspeaker. The electronic messages may be one or more of email messages, short message service (SMS) messages, multimedia message service (MMS) messages, instant message service (IMS) messages, video messaging etc. and electronic messages which do not comprise a visual element and which typically comprise an audio element, e.g. an audio message, or sound file, such as an mp3 file.

The electronic messages may be addressed to the user of the portable electronic device, as distinct from being addressed solely to the portable electronic device per se. Preferably, the personal electronic device is adapted to receive, decrypt and display electronic messages in both a first format that was initially addressed to a recipient by specifying an email address and a second format that was initially addressed to a recipient by specifying a telephone number.

The electronic messages may communicate financial information to a personal banking software application (e.g. a bank account statement), or a gambling software application (e.g. a receipt or confirmation of a bet). Electronic messages may communicate healthcare data to a healthcare software application (e.g. a patient data record, or details of a prescription). Electronic messages may communicate receipts, electronic certificates denoting money, tickets and the like. Electronic messages may comprise electronic passport data, or identity card data.

The electronic messages may comprise documents which communicate business information, such as business-related word processor or spreadsheet documents.

The message receiving module typically comprises a wireless communications transceiver, such as a Wi-Fi or Bluetooth transceiver or a cellular telecommunications network transceiver, such as a GSM, GPRS or WCDMA transceiver. The message receiving module will typically be operable to communicate bidirectionally. The personal electronic device may comprise mobile telephone functionality in which case the message receiving module typically comprises an RF receiver, such as a mobile telephone and/or cellular telecommunications network transceiver, for example, a GSM, GPRS or WCDMA transceiver. Preferably, the message receiving module is operable to receive encrypted electronic messages formatted according to internet protocol (IP), e.g. as IP messages. Preferably, electronic messages which were originally addressed to a user of the personal electronic device in formats other than internet protocol are received formatted according to internet protocol. Preferably, electronic messages in a plurality of different formats, or which were originally addressed to a user of the personal electronic device are received formatted according to internet protocol

Preferably, received encrypted messages may be stored on the personal electronic device. The personal electronic device preferably comprises user interface means (such as a user interface) which enable a user to determine whether a received encrypted message is stored on the personal electronic device. The user interface means may comprise an input device and a display.

Where the second microprocessor and secure memory are part of a removable memory device, such as an SMC card, the received encrypted messages are preferably stored on the secure memory device.

Typically, stored electronic messages will be stored in encrypted form. They may be stored in the form in which they were received, thereby ensuring that their decryption remains under the control of the second microprocessor in embodiments where decryption requires a key or secret data stored in the secure memory. However, they may have been decrypted and reencrypted. If this is the case, they are preferably reencrypted by the second microprocessor using a key which is selected so that the encrypted electronic messages which have been reencrypted require a key stored in the secure memory in order to be decrypted. Thus, the decryption of stored encrypted electronic message preferably remains under the control of the second microprocessor.

Preferably, the encrypted (or reencrypted) electronic messages are stored (whether in encrypted or unencrypted format) in the secure memory. Preferably, the second microprocessor is only operable to allow a said encrypted electronic message to be transmitted to the first microprocessor in a format which is unencrypted or decryptable using a key which is not stored in the secure memory after authentication. The received encrypted messages may be stored in an encrypted format in data storage which is accessible to the first microprocessor other than under the control of the second microprocessor, such as a solid-state memory or disc drive which is in communication with the first microprocessor. If the second microprocessor and secure memory are part of a removable memory device, the received encrypted messages may be stored in an encrypted format in a non-secure memory of the removable memory device, from where they can be retrieved by the first microprocessor. In these cases, the personal electronic device will only be operable to cause the stored received encrypted messages to be decrypted and displayed following activation. If this is the case, they are preferably reencrypted by the second microprocessor using a key which is selected so that the encrypted electronic messages which have been reencrypted require a key stored in the secure memory in order to be decrypted. Thus, their decryption remains under the control of the second microprocessor.

Thus, received encrypted messages may be stored securely. Where the second microprocessor and secure memory are part of a removable memory device and where the encrypted messages are stored in the secure memory or non-secure memory which is part of the removable memory device, this enables electronic messages to be securely received, displayed and ported from one personal electronic device to another by transferring the removable memory device to another personal electronic device. The first and second secure data is of course transferred with the removable memory device. As discussed below, some or all of the software which is executed by the first microprocessor in order to control activation and the subsequent decryption and output of electronic messages is preferably stored on the removable memory device, providing a portable unit for securely receiving, outputting and transferring electronic messages.

The personal electronic device may also be operable to input electronic messages for transmission to server means which transmits the electronic message to an addressee. The person electronic device may comprise an input device for inputting a message (which may be the same as the input device for receiving an identifier, where present). The electronic message may comprise addressee details and the remote server may be operable to transmit the electronic messages to the addressee. The input electronic messages are preferably encrypted using or with reference to a key or secret data stored in the secure memory. Preferably, the personal electronic device is operable to output the input electronic messages using an output device, but only after authentication.

Typically, the encryption of input electronic messages is carried out by the second microprocessor. Encrypted input electronic messages may be stored with received encrypted electronic messages, providing a unified secure data storage facility.

As an alternative to, or in addition to the message receiving module for receiving encrypted electronic messages, the personal electronic device may comprise a file encrypting module which is operable to receive data from a software application executed by the first microprocessor and to encrypt the received data to create an encrypted electronic message, wherein the resulting encrypted electronic message is decryptable under the control of the second microprocessor, with reference to the first secure data. In this case, the message communication module will alternatively, or also, be operable to communicate a decrypted electronic messages which was received and encrypted by the message encrypting module.

Thus, locally created data may be encrypted such that decryption and subsequent communication of the resulting encrypted electronic message using the message communication module requires the first secure data and is under the control of the second microprocessor.

This allows locally created data, such as word processor, spreadsheet, graphics and/or other documents to be encrypted under the control of the second microprocessor. They may be saved and/or decrypted as described herein in relation to the encrypted electronic messages received by the message receiving module. Typically, the encrypted electronic messages created using the message encrypting module will subsequently be processed as described in relation to the encrypted electronic messages received by the message receiving module (where present). Typically, the encrypted electronic messages created using the message encrypting module will subsequently be decrypted and output to the software application which created an encrypted document.

Accordingly, the personal electronic device may comprise a file system filter module (such as one or more file system filter drivers) comprising the said message encrypting module, which is operable to intercept requests by a software application to save files comprising messages (e.g. documents) and to encrypt the said files to 1 o

create and store an encrypted electronic message (e.g. an encrypted message comprising a document) which is decryptable under the control of the second microprocessor, with reference to the first secure data.

Preferably, the file system filter module is also operable to decrypt an encrypted electronic message which has been created and stored by the file system filter module, under the control of the second microprocessor, with reference to the first secure data. Where the second microprocessor and secure memory are part of a removable memory device, such as an SMC card, the file system filter module is preferably operable to store said encrypted electronic messages (e.g. encrypted messages comprising documents) on the removable memory device.

The personal electronic device may comprise an electronic message handling software application which is executed by the first microprocessor in use. The electronic message handling software application preferably functions as the output control module and is operable, after authentication, to cause an encrypted electronic message to be decrypted and output using the message communication module. Preferably, the electronic message handling software application causes the personal electronic device to present a user interface to a user to enable a user to select an encrypted electronic message for decryption and output. The electronic message handling software application may comprise the file system filter module, where present.

The electronic message handling software application may not be executed until authentication has taken place. Preferably, the electronic message handling software application is loaded from the removable memory device into memory which is integral to the personal electronic device and executed by the first microprocessor. The electronic message handling software application may initially be encrypted, at least in part, and may only be decrypted once the authentication has been completed. Decryption of the electronic message handling software application may be carried out by the second microprocessor with reference to a key or secret data stored in the secure memory.

The electronic message handling software application may be executable before it has been activated, but not operable to output the received encrypted electronic messages until authentication has been completed. I y

The electronic message handling software application may comprise program code which, when executed, causes the first microprocessor to request that the second microprocessor decrypts a received electronic message. The second microprocessor may not be operable to decrypt a received electronic message until the second microprocessor has completed the authentication procedure, thereby preventing the personal electronic device from displaying a received electronic message until after the completion of the authentication procedure.

The electronic message handling software application may be executed responsive to receipt of an encrypted message, although it will not be operable to cause the received encrypted message to be output until after authentication.

Following authentication, the personal electronic device (typically responsive to execution of the electronic message handling software application) may present a suitable or specific secure or non-secure user interface to perform all necessary message related (e.g. view, store, reply, forward etc.) or message content related activities (view, save, transfer etc.). The personal electronic device (typically responsive to execution of the electronic message handling software application) preferably presents a user interface to a user which, typically amongst other features, enables them to select an action from options including the options of saving and/or sending the received encrypted message in an unencrypted form. For example, the electronic message handling software application may pass the decrypted message to a message handler of a non-trusted electronic message handling software application, such as a conventional email handling software application.

The personal electronic device may receive and store permission data which determines whether a user can cause a said security-related function to occur and/or can carry out the authentication procedure. Permission data may be stored in the secure memory. Permission data may relate to a specific user. Permission data may relate to all personal electronic devices to which it is sent which have specific properties. Permission data may be received in a received encrypted message and determine the functionality which is available to a user in connection with that specific received encrypted message.

The electronic message handling software application may allow a user to save and/or send the received encrypted message in an unencrypted form dependent on permission data. Similarly, permission data may determine the options provided to a user by the personal electronic device (responsive to execution of the electronic message handling software application) following activation.

Permission data may determine whether a user can communicate using a specific communications interface (e.g. a mobile telecommunications interface), or impose limitations on the use which they can make of specific communications interface. Permission data may determine the types of electronic message which a user can cause to be decrypted and viewed, or messaging handling options available to a user. Permission data may determine the maximum size of encrypted messages which a user can send and/or receive.

Whether a user can cause a security-related function to occur may depend on one or more properties of the personal electronic device, such as its operating system, hardware capabilities, software capabilities and/or the date and time.

Permission data may determine whether a user can complete the authentication procedure, for example, it may specify that a particular user can only complete the authentication procedure at certain times.

The personal electronic device (typically responsive to execution of the electronic message handling software application) may be operable to cause a received encrypted message to be stored, in encrypted form, in a data store which is shared with other software applications. For example, a received encrypted message might be stored in a file structure which specifies the contents of an email box of an email handling software application. However, because it is stored in encrypted form, it cannot be output other than under the control of the electronic message handling software application, following activation.

The personal electronic device may also be operable to encrypt an electronic message and transmit it, for example to an addressee. The personal electronic device may require authentication to be completed before the message is encrypted and/or transmitted. Typically, the message will be encrypted by the second microprocessor with reference to a key stored in the secure memory. The electronic message handling software application may also control the encryption and transmission of an electronic message in order to send it on to an addressee. The message receiving module may also be operable to receive non-encrypted electronic messages. The electronic message handling software application may also enable received non-encrypted electronic messages to be displayed. The electronic message handling software application may enable received non- encrypted electronic message to be displayed only after authentication.

The electronic message handling software application may be stored in memory which is directly accessible by the first microprocessor. The electronic message handling software application may be stored in non-secure memory which is part of the removable memory device. The electronic message handling software application may be stored in encrypted form. The electronic message handling software application may be stored in the secure memory.

The personal electronic device may comprise middleware software (and typically also operating system software) which functions as the input module. The middleware software is preferably executed on the first microprocessor in use and causes the first microprocessor to receive an identifier and to transmit the identifier to the second microprocessor so that the second microprocessor can carry out the authentication procedure which requires the second secure data. The middleware software may be stored, at least initially, on the removable memory device (typically in the memory which is readable on demand) and the personal electronic device may be operable to automatically load up and execute the middleware software from the removable memory device responsive to the personal electronic device being switched on and/or responsive to detection that a removable device has been brought into removable electronic communication with the first microprocessor.

The middleware software may also be operable to cause the electronic message handling software to be executed responsive to authentication.

The middleware software may present an application programming interface to the electronic message handling software, wherein the application programming interface includes means to instruct the middleware software to cause an electronic message to be encrypted and/or decrypted by the second microprocessor. The application programming interface may comprise means to identify a key which is stored in the secure memory and which is to be used by the second microprocessor to encrypt and/or decrypt an electronic message. Preferably, the electronic message handling software application comprises program code which, when executed on the first microprocessor, causes the personal electronic device to provide a user interface including the display of text or icons (perhaps in the form of an inbox) denoting a plurality of received electronic messages, including more than one format of message, and which allows the user to select a received electronic message for decryption and output using the output means. The display of text or icons denoting a plurality of received electronic messages may only be viewable following activation. Preferably, the user interface enables a user to select electronic messages for decryption and output which are in a plurality of formats, wherein at least one format of electronic message is a format in which the address of the electronic message is denoted by an email address and at least one format of electronic message is a format in which the address of the electronic message is denoted by a telephone number.

The invention extends in a second aspect to a system comprising server means and a plurality of personal electronic devices according to the first aspect of the present invention.

Preferably, the server means (such as a server or cluster of servers) are in communication with a first communications network for receiving electronic messages and a second communications network for communication between the server means and the plurality of personal electronic devices. The server means may be in communication with and receive electronic messages from a plurality of first communications networks, which electronic messages are encrypted and transmitted to the personal electronic device.

The first and second communications networks may be the same network, but typically the first and second communications networks will be different networks. The second communications network typically consists of or comprises a mobile communications network such as a cellular telecommunications network (for example, a GSM, GPRS or WCDMA network) or other communications network or link (for example, an ethemet and/or virtual private network, or a broadband Wi-Fi, Bluetooth, WiMax or IrDA link).

Preferably, the second communications network supports the transmission of data by internet protocol and the secure server transmits the encrypted electronic messages to the personal electronic device by internet protocol, for example as IP messages. Where the electronic messages received by the secure server are in a plurality of formats, the secure server preferably converts the electronic messages received by the secure server into a single format for transmission by internet protocol to the personal electronic device.

The first communications network may comprise or consist of an internet protocol network. The first communications network may comprise a public telephone network. The server means may receive electronic messages in a plurality of formats. For example, the server means may receive electronic messages in two or more formats. The formats may be selected from the group comprising: email messages, SMS messages, MMS messages, IMS messages and video messages. The electronic messages preferably communicate information to a user of the portable electronic device. The electronic messages may comprise visual information which is suitable for display on a display. The electronic messages may comprise audio information which is suitable for output through a loudspeaker.

The server means may be operable to receive electronic messages in two or more formats in which at least one format of electronic message is a format in which the address of the electronic message is denoted by an email address and at least one format of electronic message is a format in which the address of the electronic message is denoted by a telephone number.

The server means preferably comprises an address resolving module (for example, a software module which, when executed, refers to a look-up table, database or collection of rules) for resolving one or more addressees specified in received electronic messages to identifiers of a personal electronic device and/or a removable memory device associated with the or each addressee, and the server means may be operable to transmit the received electronic message to the personal electronic device identified by the address receiving module, or the personal electronic device comprising the removable memory device identified by the address receiving module.

The electronic message will typically be encrypted using a key or shared secret specifically for enabling the electronic message to be decrypted by a particular personal electronic device which has a complementary key or the same shared secret stored in its secure memory. Electronic messages in two or more formats may be encrypted and transmitted to personal electronic devices in the same format. Electronic messages in two or more formats may be treated in the same way by the system until they are decrypted by a personal electronic device.

The server means and the secure memory of a personal electronic device (preferably the integrated section of memory) may share a secret and the server means may use the shared secret to encrypt an electronic message for transmission to the personal electronic device.

The secure memory of a personal electronic device (preferably the integrated section of memory) may store a private key and the server means may use the public key which is complementary to the stored private key to encrypt an electronic message for transmission to the personal electronic device.

The second microprocessor of a personal electronic device may generate a first key and transmit that key securely (for example, in an encrypted format) to the server means, while retaining a second key which is complementary to the first key within the secure memory of the personal electronic device (preferably within the integrated section of memory) and the server means may use that first key to encrypt an electronic message for transmission to the personal electronic device. The first and second keys could be established by negotiation between the server means and the second microprocessor, for example using the Diffie-Hellman key exchange protocol. Where a symmetric key algorithm, such as DES or Triple-DES, is used for encrypting and decrypting the electronic message, the first key and second key will preferably be the same. Where an asymmetric key algorithm, such as the RSA algorithm, is used for encrypting and decrypting the electronic message, the first key and second key will preferably be different to each other.

The electronic message may be encrypted using the first key or a key derived from the first key. The electronic message may be decrypted using the second key or a key derived from the second key. The server means may encrypt part of the electronic message, or all of the electronic message. The server means may use a first key to encrypt a single electronic message or a plurality of electronic messages addressed to a particular user. The first microprocessor may periodically generate and transmit a new first key to the server means. The server means may be operable to determine whether an electronic message received using the first communications network should be transmitted securely to a personal electronic device and, if this is the case, to cause the electronic message to be encrypted and then transmitted to a personal electronic device using the second communications network. If this is not the case, the electronic message will typically be transmitted to a personal electronic device without encryption.

The server means may comprise a secure server to which electronic messages which are to be encrypted are routed and which is operable to carry out the process of encrypting an electronic message.

The server means will typically determine whether an electronic message received using the first communications network should be transmitted securely to a personal electronic device by analysing the received electronic message to determine whether it contains a security marker.

The server means may be operable to determine a security level or classification associated with an electronic message, for example from a security marker included in a received electronic message or permission data associated with an addressee of the electronic message, and to include one or more security markers within the encrypted electronic message which is sent to the personal electronic device, which permission information can be interpreted by the electronic message software application (discussed below) and which affects the actions which a user of the personal electronic device can carry out in relation to the electronic message. For example, security markers may determine one or more of whether a user can delete an encrypted electronic message, whether they can store it other than in the secure memory and, if so, whether they can store it in an unencrypted format.

According to a third aspect of the present invention there is provided a memory device ("the removable memory device") for removable communication with a memory interface of a personal electronic device, the memory device comprising secure memory which stores (i) first secure data which is required for a security- related function of a personal electronic device to be carried out, and (ii) second secure data which is required for an authentication procedure, wherein the memory device further comprises a microprocessor ("the second microprocessor") which controls access to the data stored in the secure memory, wherein the memory device further comprises program code which is readable on demand by a personal electronic device to which the memory device is interfaced and which, when the memory device is interfaced with a personal electronic device having a personal electronic device microprocessor ("the first microprocessor") causes the personal electronic device to function as the personal electronic device of the first aspect of the invention.

The program code, or part thereof, may be stored in the secure memory. The program code, or part thereof, is preferably stored in a section of memory from which at least a part of the computer program may be uploaded by the microprocessor of a personal electronic device with which the removable device is interfaced, on demand. The program code may comprise an electronic message handling software application according to the first aspect of the invention. The program code may comprise an electronic message handling software application according to the first aspect of the invention in encrypted form. The program code may comprise a user identification software application according to the first aspect of the invention. The program code may comprise middleware software according to the first aspect of the invention.

Preferably, the removable memory device comprises an interface for enabling the second microprocessor to electronically communicate with the first microprocessor of a personal electronic device with which it is brought into communication.

Preferably, the secure section of memory of the removable memory device stores a decryption key or secret data which is required to decrypt an encrypted electronic message received by the personal electronic device.

The removable memory device may further comprise one or more encrypted electronic messages received by a message receiving module of a personal electronic device with which the removable memory device is or was in electronic communication.

Further features of the removable memory device correspond to the features described in relation to the removable memory device of the first aspect of the invention.

According to a fourth aspect of the present invention, there is provided a method of regulating a security-related function of a personal electronic device which comprises a first microprocessor which controls the personal electronic device, secure memory which stores (i) first secure data which is required for a security-related function of the personal electronic device to be carried out, and (ii) second secure data which is required for an authentication procedure; and a second microprocessor which is in communication with the first microprocessor and the secure memory and which controls access to the data stored in the secure memory; the method comprising carrying out a security-related function of the personal electronic device which requires the first secure data only after the completion of an authentication procedure which requires the second secure data.

Further preferred and optional features of the method correspond to those discussed in relation to the first three aspects of the invention.

Description of the Drawings

Example embodiments of the invention will now be illustrated with reference to the following Figures in which:

Figure 1 is a schematic diagram of key components of a system for receiving, viewing and storing electronic messages, such as emails, SMS messages, MMS messages, IMS messages and video messages, on a personal electronic device;

Figure 2 is a flow chart of the procedure carried out by the server means responsive to the receipt 100 of an electronic message by the messaging server;

Figure 3 is a flow chart of procedures carried out by the personal electronic device responsive to receipt 120 of an electronic message through the second communications network from the secure server/messaging server;

Figure 4 is a diagram of a secure messaging system for secure communication between mobile devices and a trusted server;

Figure 5 is a diagram of a secure messaging system for secure end to end communication between mobile device. Figure 6 is a schematic diagram of a personal electronic device according to a second example;

Figure 7 is a schematic diagram of procedures carried out by a personal electronic device according to a second example, to allow normal access to a SIM card; and

Figure 8 is a message sequence chart of procedures carried out by a personal electronic device according to the second example, in response to insertion of an incorrect PIN or in response to the removal of an SMC card.

Detailed Description of Example Embodiments

Example 1 - Secure Message Handling using an SMC card

Figure 1 is a schematic diagram of key components of a system for receiving, outputting and storing electronic messages, such as emails, SMS messages, MMS messages, IMS messages and video messages, on a personal electronic device.

In this example, the security-related function is the decryption and output of received encrypted electronic messages to a user. The decryption requires first secure data. Decryption and output will not occur until the user of a personal electronic device has input an identifier which has been verified with reference to identity verification data (which constitutes the second secure data).

Server means comprise a messaging server 2 and a secure server 4 which stores one or more encryption keys 6 or secret data. Messaging server 2 is connected to the first communication network 8, such as the internet or a private ethemet, for receiving email messages from remote servers. Other formats of. messages may be received through the same communications network, or the messaging server may be connected to additional communications networks, such as wired or wireless telecommunications networks, for receiving other formats of electronic messages.

Persons skilled in the art will recognise that server means may be implemented on a single computer or a cluster of computers. In an alternative embodiment, the server means comprises a server which combines the functions of the messaging server and the secure server. The system comprises at least one personal electronic device 10 which is in communication with the server means via a second communication network 12, such as a cellular mobile telecommunications network. The server means communicates with the or each personal electronic device in internet protocol (IP) over the cellular mobile telecommunications network.

The personal electronic device includes a microprocessor 14 (functioning as the first microprocessor) which is in communication with a memory 16 (and optionally additional types of storage) and one or more output devices in the form of a display 18 and/or a loudspeaker 19. The output devices and the software executed on the first microprocessor which drives the output devices constitute an output module. The microprocessor of the personal electronic device is also in electronic communication with a secure media card (SMC) 20 (functioning as a removable memory device) which is located in a removable memory card slot of the personal electronic device. The SMC includes a microprocessor 22 (functioning as the second microprocessor) and integrated secure memory 24. Access to the data stored in the integrated secure memory is controlled by the second microprocessor 22. This arrangement of integrated secure memory in a removable non-volatile solid-state memory device, access to which is controlled by a built-in microprocessor, is generally known in the art as tamper-proof silicon. The SMC also includes a section of memory which is readable on demand by the first microprocessor 26. Some of this section of memory which is readable on demand may be used as secure memory under the control of the second microprocessor by storing data in the section of memory which is readable on demand in an encrypted format wherein the decryption key or other data required to decrypt the data is stored in the integrated secure memory.

The integrated secure memory stores an encryption key which is complementary to the encryption key stored by the server means, or shared secret data which is shared with the server means, so that the server means can encrypt an electronic message such that the encryption key or shared secret data stored in the secure memory is required for the electronic message to be decrypted.

The secure media card is typically a card according to the ISO/IEC 7816 specification, or a Secure Digital (SD), miniSD or microSD memory cards according to standards published by the SD Association (www.sdcard.org) or a SecureMMC card according to standards published by the MultiMediaCard Association (www.mmca.org). (SD is a trade mark of Toshiba Corporation, miniSD is a trademark of SD association, microSD is a trade mark of SanDisk Corporation, SecureMMC is a trade mark of the MultiMediaCard Association).

The personal electronic device may include one or more additional removable memory devices, such as a SIM card for use in authentication when a cellular mobile telecommunications network functions as the second communications network.

Figure 2 is a flow chart of the procedure carried out by the server means responsive to the receipt 100 of an electronic message by the messaging server. Each received message has at least one addressee to whom the message is ultimately addressed. In the case of an email message, the addressee could be identified by an email address. In the case of an SMS, MMS, IMS or another type of message sent through a telephone network, the addressee could be identified by a telephone number. The server means determines to which personal electronic device the electronic message should be sent 102 from the addressee details of the electronic message. The server means comprises a data store (such as a look up table or database) which can be used to relate address details (such as a telephone number or email address) to an address (such as an internet protocol address or telephone number) to which the electronic message should be sent. The address to which the electronic message should be sent may be an address (such as an internet protocol address or telephone number) of a personal electronic device. However, it may be an address (such as an internet protocol address) of an application which is executed on the personal electronic device or an address (such as an internet protocol address) of an SMC associated with a personal electronic device.

The messaging server determines whether the received electronic message is to be transmitted securely 104. This may be achieved by looking for tags within the received email message. If the electronic message is not to be transmitted securely, it is then transmitted 106 to the personal electronic device(s) of the addressee(s) of the electronic message without further encryption. If the electronic message is to be transmitted securely, it is relayed 108 to the secure server which encrypts 110 the electronic message using the stored key and then transmits 112 the resulting encrypted message to the personal electronic device including a security marker to indicate that it is a secure message. One skilled in the art will also recognise that the electronic message could be encrypted and relayed to the personal electronic device by other means. For example, a secure session could be established between the secure server and the personal electronic device, or a specific software application executed on the personal electronic device, or the second microprocessor of the personal electronic device. In this case, a shared secret, stored in both the secure server and the integrated secure memory of the SMC associated with a personal electronic device, can be used in a protocol for encrypting and transmitting the electronic message.

The result should be that the electronic message is sent in an encrypted format such that a key, or shared secret, stored in the integrated secure memory of the SMC of the user to which the electronic message is addressed, is required in order for the electronic message to be decrypted. Thus, a secure context is established between the secure server and the integrated secure memory of the SMC of the device of the addressee.

The encrypted electronic message which is sent to the personal electronic device may include further security markers which determine the functionality which will be available to a recipient of the encrypted security message, for example whether they can view, save, delete or print the electronic message. The security markers may depend on one or more rules or profiles allocated to an addresses, or group or class of addressees.

Whether or not they are encrypted, electronic messages in different formats, such as email messages, SMS messages, MMS messages, IMS messages and video messages, are preferably all sent across the second communications network as IP messages. Where the messages are encrypted, this allows the secure transmission of different types of message in a unified fashion.

Figure 3 is a flow chart of procedures carried out by the personal electronic device responsive to receipt 120 of an electronic message through the second communications network from the secure server/messaging server. Middleware software originally loaded from the SMC and installed on the personal electronic device and executed by the microprocessor of the personal electronic device determines whether the received electronic message is a secure message (i.e. an electronic message which has been encrypted by the secure server) from the security markers included in the received electronic message. If the received message is not a secure message, it is passed 124 to the electronic message handler of open message handling software installed on the personal electronic device, for example, a conventional email application or SMS message handling application which enables a user to select and then view or play 126 unencrypted messages. The conventional email application (which will typically be preinstalled on the personal electronic device by the manufacturer or an OEM distributor) will then typically provide conventional messaging handling features, such as a user interface allowing a user to select, view, edit, compose and send electronic messages.

If, however, the received electronic message is determined to be a secure message, it will require to be decrypted by a procedure requiring a key or secret data stored in the secure memory before it can be displayed, played or otherwise output to a user. A secure message handling application (functioning as the electronic message handling software application) is then loaded from the built-in memory of the personal electronic device or from the section of memory of the SMC which is readable on demand, and executed.

The secure message handling application presents a user interface requesting that the user inputs identification data 126, such as a PIN which can be input using a keyboard or touch screen, or biometrical information, such as a fingerprint, which can be input using a fingerprint reader. The portion of the secure message handling application which controls input of identification data and input devices constitutes at least part of an input module.

The input identification data is sent by the personal electronic device microprocessor to the microprocessor of the SMC where it is compared with identity verification data (which constitutes second secure data) stored in the integrated secure memory. If, following comparison of the input identification data with the identity verification data, the microprocessor determines 134 that the user has identified themselves, the microprocessor allows decryption 136 and display 138 of the received electronic message, or at least part thereof.

Decryption requires data (first secure data) which is stored in the integrated secure memory in the form of a key or shared secret data which is shared with the secure server This means that decryption is under the control of the microprocessor of the SMC. Typically, the microprocessor of the SMC decrypts the received electronic message and transmits the corresponding plain text / decrypted data to the microprocessor of the personal electronic device which displays the electronic όό

message. In an alternative embodiment, the microprocessor of the personal electronic device decrypts the received electronic message using a decryption key provided by the microprocessor of the SMC by a procedure requiring the first secure data.

The user is then provided with the option 140 of replying to/forwarding or storing the electronic message securely. If the user chooses to store the message securely, the electronic message is stored in encrypted form on the SMC, for example, in the section of memory on the SMC which is readable on demand. The electronic message may be stored in the encrypted form in which it was received or may be reencrypted. In either case, a key or secret data stored in the secure memory will be required to decrypt the electronic message.

If the user chooses to reply to the electronic message or forward the electronic message, a new electronic message is created 142, using input devices such as a keyboard, camera etc., encrypted 144 and transmitted 146 to the secure server for onward transmission to an addressee. The electronic message will be encrypted using secret data which is shared with the secure server or an encryption key which is complementary to a decryption key stored on the secure server. If the created message is stored 148 on the personal electronic device, it will be stored along with the received electronic messages, in encrypted form, such that a key or secret data stored in the integrated secure memory is required for it to be decrypted.

The user may be presented with the option of storing the received electronic message in a non-encrypted open form. If they wish to do this, the personal electronic device determines 150 whether they have permission to do this. This will be determined by the permission data included in the received electronic message by the secure server. If they have permission to do this, the message will be transferred 152 in a non-encrypted open form to the open message handling software.

The middleware software, the secure message handling application, and stored encrypted electronic messages are stored in section of memory which is readable on demand of the SMC. If the SMC is removed, the secure message handling application terminates. The user may insert the SMC into another personal electronic device. They will then need to identify themselves before the encrypted messages can be decrypted and viewed. Thus, they can securely carry around the encrypted messages on the SMC and transfer them to another personal electronic device. At least the middleware software is typically configured to be automatically loaded onto the personal electronic device from the section of memory which is readable on demand when the SMC is inserted into a personal electronic device. The middleware software then loads up any missing device drivers from the section of memory which is readable on demand. The middleware software controls entry by a user of an identifier, and the relay of that identifier to the second microprocessor where it is compared against the stored identity verification data. Once the user has identified themselves, the middleware software causes the secure message handling software to be executed by the personal electronic device microprocessor. The secure message handling software application is stored in encrypted form in the section of memory of the SMC which is readable on demand and is decrypted by the SMC microprocessor using a key stored in the integrated secure memory, following authentication.

The middleware software provides an API which can be used by the secure message handling software to instruct the microprocessor of the SMC to encrypt or decrypt an electronic message using a specific key which is stored in the integrated secure memory. The middleware software typically includes functionality to authenticate with the secure server and can issue a request to the secure server to initiate a secure transaction of data with the secure server, or react to a challenge from the secure server. Where the secure message handling software needs to communicate securely with the secure server (e.g. to receive an encrypted electronic message or to send an encrypted electronic message), it does so through the middleware software. There may be multiple layers of authentication between the middleware software and the secure server.

Preferably, the data stored in the integrated secure memory (such as one or more keys or secret data shared with the secure server) is sufficient to enable decryption of the received electronic messages, so there is no need for the personal electronic device to communicate with the secure server, or to be in communication with the secure server, in order to allow the decryption and viewing of received electronic messages.

Figures 4 and 5 illustrate two alternative approaches for secure communication between users 200 of a personal electronic device and a trusted server 218 in a message system, such as a corporate email and/or messaging system, which is considered to be secure. The user creates 202 a message using a messaging application 204, such as Microsoft Outlook (Outlook and Microsoft are trade marks of Microsoft Corporation). When they wish to send the message, the messaging program invokes 206 middleware 208 which intercepts the message and requires the user to authenticate (e.g, by entering a PIN) if they have not already done so. The message is then digitally signed and encrypted under the control of the second microprocessor, on the SMC card, following a request 210 for a session key to be generated and transmitted 212 to the middleware, along with an encryption key for securing and locally storing the message. The message is then transmitted 214 to a secure mail receiving application 216 on the trusted server 218 after a secure link is formed between the middleware and the secure mail receiving application using the session key. The address of the mail server to which the messaging program would otherwise have sent the message is appended to the message so that the encrypted message can be routed via that server, if appropriate.

As well as creating the outgoing encrypted message, the middleware is also operable to output 220 the encrypted message back to the messaging program for storage. Thus, the encrypted message can be stored by the messaging program in its usual file structure, but cannot be read except under the control of the second microprocessor, with reference to the encryption key which was previously generated. The middleware can be conveniently implemented as part of an SMTP server application.

Once the message has been securely relayed to the trusted server, the trusted server determines whether to transmit the message to a user securely, with reference to permission data, in the form of one or more policies. If the trusted server determines that the message should be sent without encryption, for example if it is addressed to a recipient who is not part of a group of users who communicate securely, it relays it to the mail server at the address which is appended to the message. If the message should be sent securely, it is relayed securely to a second trusted server 221.

In order to receive an electronic message, the messaging program periodically checks for emails with the second trusted server, for example using a pull email transfer protocol, such as POP3. Typically, the messaging program is also operable to downloaded non-secure emails periodically from a non-secure server. However, requests to receive secure emails through the secure messaging system are intercepted by the middleware program which creates a secure session with a secure mail sending application 222 on the second trusted server. Alternatively, emails may be delivered automatically to the personal electronic device by a push email forwarding protocol, from the second trusted server. Encrypted messages are received from the second trusted server 224 and transferred to the middleware of the personal electronic device. The middleware requires a user to authenticate themselves if they have not already done so, under the control of the SMC, decrypts the received encrypted message, re-encrypts it using a storage key obtained 226 from the SMC card, and transmits the resulting encrypted message to the messaging program which stores it in its filing system. In order for a user to view the encrypted message, it must first be decrypted by the middleware using a key obtained from the SMC card. The middleware may also function to restrict security-related action which can be carried out by a particular user or on a particular personal electronic device, according to permission data (such as a policy). For example, the middleware may block the receipt of non-secure messages.

In the embodiment illustrated in Figure 5, end-to-end security is provided for sending electronic messages, such as email, text messages and instant messages, between personal electronic devices, perhaps over non-secure communications networks. A client key management module 228 is operable to store public keys belonging to third parties and to obtain any public keys which are not already stored from an external key management server 230 where required. As before, a user interacts with a messaging application. The messaging application requests a symmetric key from the SMC. When the message is ready for sending, it is encrypted by a middleware application using the received symmetric key. The symmetric key is encrypted using the public keys of both the recipient and the sender and sent with the resulting encrypted message via a non-secure email server 232. The electronic message is encrypted as before so that decryption is under the control of the second microprocessor and returned to the messaging application in encrypted form for storage with other messages. The electronic message is also digitally signed using the private key of the sender (which forms a key pair with their published public key) for the purpose of non-repudiation.

A messaging application of the personal electronic device which receives the electronic message requires a user to authenticate before enabling decryption and viewing of the received electronic message. A plug-in to the messaging application, functioning as a message decryption module, looks up the public key of the sender (again obtaining a copy from a key management server where required), decrypts the O /

received encrypted key using the recipient's private key (which forms a key pair with their published public key), which is stored in their SMC card secure memory, retrieves the symmetric key and decrypts the electronic message to enable it to be viewed by the user. The signature of the received electronic message is checked to verify the identity of the party that transmitted the electronic message. The electronic message may be re-encrypted under the control of the SMC card and stored by the messaging application.

Although the examples described above relate to discrete messages, individual sections of streaming data (e.g. packets) can be encrypted, transmitted and decrypted in the same way as electronic messages. Thus, the system can be used to provide secure voice communications by encrypting parts of voice data (e.g. packets of Voice over IP data) at a first personal electronic device for periodic transmission to a second electronic device, decryption and reconstitution to provide a continuous voice output.

Example 2 SIM Activation/De-activation using the SMC (or another secure token)

Many personal electronic devices include mobile telephone functionality and include a mobile telephone SIM card which performs an authentication role when the mobile telephone transceiver connects to a mobile telephone network, such as a GSM network. Normally, a user must enter the SIM PIN to in order to gain access to the network and/or access the SIM internal file structure. If an incorrect value is entered for three consecutive attempts the PIN is blocked and access to the SIM denied, thereby disabling voice and data connections using the mobile telephone network.

A SIM with a blocked PIN can be recovered using the Pin Unblock Key (PUK) which can be obtained from the relevant network operator. This allows the PIN to be changed to a new value.

PIN entry offers comparatively weak security as the PUK can be obtained from the network operator with little or no control, thus allowing a malicious user to unblock the SIM PIN at will. Furthermore, with knowledge of the PIN, a user can disable the requirement of entering the PIN each time, reducing security.

In this example, the security-related function provides improved control of the SIM and the SIM PIN mechanism, through the use of a SIM control software agent and an OO

SMC to provide an alternative user authentication mechanism. The SIM control agent will take control of the PIN (i.e. amend the PIN to a value which is kept confidential from the user.) The new PIN is stored in the integrated section of memory of the SMC.

Figure 4 illustrates a personal electronic device 200 having a mobile telephone transceiver 202 (such as a GSM interface) which requires a SIM card 204, a secure media card 206 (functioning as a removable memory device) interfaced with a memory interface of the personal electronic device, and a microprocessor 214 of the personal electronic device (functioning as the first microprocessor). The SMC comprises a microprocessor 208 which regulates access to secure memory including an integrated section of memory 210. The SMC comprises memory which is readable on demand 212 by the microprocessor of the personal electronic device through a memory card interface.

Access to the SIM is controlled by using the SMC to generate and issue the PIN to the SIM each time the SMC is inserted and/or the handset is reset. Initially, the SMC is configured with the original SIM Integrated Circuit Card Identifier (lccld) PIN and PUK, which are stored in the integrated section of memory of the SMC (as first secure data). The memory which is readable on demand comprises software which is uploaded to the personal electronic device and executed by the personal electronic device microprocessor in use and which includes middleware software comprising a SIM control agent.

Before the SIM card is activated, an authentication step is carried out. The authentication step may be the input of a PIN or biometric identifier from a user which is compared with identity verification data (functioning as the second secure data) stored in the integrated section of memory of the SMC. The SIM control agent then verifies that the SIM present in the device is the specific device that is to be controlled by comparing the lccld stored in the integrated section of memory of the SMC with that of the SIM. If the lccld matches, the SIM control agent ensures that:

a) the SIM PIN verification is enabled and b) the PIN stored in the integrated section of memory of the SMC can be verified with the SIM. If both a) and b) are satisfied, the SIM control agent then commands the SMC to generate a new PIN. The SIM control agent then changes the value of the PIN for the SIM and the new value is stored in the integrated section of memory of the SMC.

If either a) or b) are not satisfied, the SIM PIN mechanism is deemed to have been tampered with. The SIM control agent logs that an access violation has occurred and a message is sent to an appropriate remote server. The SMC then uses the PUK of the SIM to regain control of the SIM PIN by changing the SIM PIN and ensuring that the SIM is set to require a PIN.

Upon removal of the SMC, the SIM control agent resets the SIM so that it does not function to allow a telecommunications link to be created until the current PIN has been supplied. The SIM card can be reset by the SIM control agent causing the mobile telephone transceiver to be reset. For example this can be achieved on a Windows Mobile 5.0 device via a standard TAPI call as shown in the following line of code:

hres = lineSetEquipmentState( hLine, LINEEQUIPMENTSTATE_NOTXRX) ;

As the PIN is generated by the microprocessor of the SMC and remains stored in the integrated section of memory, the PIN number remains secret and unavailable to the user. Thus, the SMC is required in order to access the SIM or for a telecommunication link to be created which requires the SIM for authentication.

This is still vulnerable in that the user may obtain the PUK from the network operator and change the SIM PIN directly thus gaining access to the SIM, either on the same device or in a different handset entirely. This can however be detected by the SIM control agent when the SMC card is next inserted or when the device is next reset as the SIM PIN will be different to the one stored in the SMC. Should such a case arise the error will be logged for subsequent reporting to a server side component and the SIM PIN secured again by changing the current PIN using the PUK. This procedure is shown in the message sequence chart depicted in Figure 6.

Example Three

In a third example embodiment, the middleware software loaded from the SMC onto the personal electronic device and executed by the personal electronic device microprocessor comprises or consists of a file system filter (functioning as the file system filter module). File system filters are driver modules which intercept and modify communications between software applications and a filing system. The file system filter is operable to intercept attempts to save or modify documents such as a word processor documents, spreadsheets, graphics files, or other application records, from applications executed by the personal electronic device microprocessor, and to cause these documents to be encrypted such that first secure data is required for their subsequent decryption. The documents are considered to be electronic messages and the resulting encrypted electronic messages are typically stored on the SMC, along with any encrypted electronic messages received from the server means. They can therefore be ported from one personal electronic device to another by transferring the SMC.

Following activation, the file system filter may enable applications to open the stored encrypted files by causing the encrypted document files to be decrypted, under the control of the SMC microprocessor, with reference to the first secure data, and output to applications executed on the personal electronic device which can work with those documents. Thus, locally created and edited content may be stored securely with activation required before securely stored documents can be opened. If the SMC is removed from the personal electronic device, the stored messages are removed from the personal electronic device with the SMC. If the SMC is interfaced with another personal electronic device, activation is required before the encrypted messages can be opened using the new personal electronic device.

Example Four

In order to provide improved control of security-related functions, policies (functioning as permission data) may be provided which determine the functionality available to a particular user, or by any user in relation to a particular message, or by any user of a personal electronic device with specific properties. Policies can be distributed to individual personal electronic devices, where they are typically stored in the secure memory, or as part of encrypted electronic messages. Functionality which may be determined by policies includes whether a user may decrypt and read an electronic message, whether they may save an electronic message in decrypted form, whether they can use a specific communications interface of the personal electronic device (e.g. a GSM, GPRS or Wi-Fi interface), the maximum size of message that they may send, where they may send messages to, the types of messages they can send, and whether they can make specific types of communication (e.g. international telephone calls).

Policies may also determine the circumstances under which authentication can occur. For example, policies may determine when users in general, or one or more specific users, can authenticate.

Policies may determine functionality which is available on personal electronics devices with specific properties, such as specific operating systems, specific installed software applications and/or specific hardware features. Policies may take the form of data specifying access rules.

Further modifications and variations may be made within the scope of the invention herein disclosed.

Claims

1. A personal electronic device comprising:

a first microprocessor which controls the personal electronic device;

secure memory which stores (i) first secure data which is required for a security-related function of the personal electronic device to be carried out, and (ii) second secure data which is required for an authentication procedure;

a second microprocessor which is in communication with the first microprocessor and the secure memory and which controls access to the data stored in the secure memory;

2. A personal electronic device according to claim 1 , wherein the second microprocessor and the secure memory is part of a removable memory device which is in removable electronic communication with the first microprocessor through an interface of the personal electronic device.

3. A personal electronic device according to claim 2, wherein the removable memory device is in removable electronic communication with a memory card interface of the personal electronic device.

4. A personal electronic device according to any one preceding claim, wherein the authentication procedure comprises providing an identifier to a remote server, wherein the identifier is, or is derived from, the second secure data.

5. A personal electronic device according to any one preceding claim, wherein the authentication procedure comprises exchanging information with a remote server using a wireless communications interface.

6. A personal electronic device according to any one preceding claim, which comprises an input module for receiving an identifier, wherein the second secure data comprises identity verification data, and wherein the authentication procedure is an identity verification procedure which verifies an identity using the received identifier and the identity verification data.

7. A personal electronic device according to claim 6, wherein the input module comprises an input device for inputting an identifier received from a user of the personal electronic device.

8. A personal electronic device according to claim 6, wherein the input module is operable to receive a identifier from a device which is connected to the personal electronic device.

9. A personal electronic device according to claim 8, wherein the input module is operable to receive an identifier from a SIM card removably attached to the personal electronic device.

10. A personal electronic device according to any one preceding claim, wherein the security-related function which requires the first secure data is the creation of a secure context between a software application executed on the personal electronic device and a remote server.

11. A personal electronic device according to any one of claims 1 to 9, wherein the security-related function which requires the first secure data is the activation of a secure token which has an authentication role in the creation of a wireless communications link using the first secure data.

12. A personal electronic device according to claim 11 , wherein the secure token is a SIM card, the first secure data comprises the PIN number of a SIM card and the security-related function comprises activating the SIM card by providing the PIN number to the SIM card.

13. A personal electronic device according to any one of claims 1 to 9, further comprising: a message receiving module for receiving encrypted electronic messages,

14. A personal electronic device according to claim 13, wherein the message receiving module is operable to receive encrypted electronic messages formatted according to internet protocol.

15. A personal electronic device according to claim 13 or claim 14, wherein received encrypted electronic messages are stored on the personal electronic device.

16. A personal electronic device according to any one of claims 13 to 15, wherein received encrypted electronic messages are stored on a removable memory card interfaced with a memory card interface of the personal electronic device, wherein the removable memory card comprises the secure memory and second microprocessor.

17. A personal electronic device according to any one of claims 1 to 9, further comprising:

a message encrypting module which is operable to receive data from a software application executed by the first microprocessor and to encrypt the received data to create an encrypted electronic message, wherein the resulting encrypted electronic message is decryptable under the control of the second microprocessor, with reference to the first secure data;

a message communication module for communicating a decrypted electronic message which was encrypted by the message encrypting module;

an output control module which is operable, following the completion of the authentication procedure, to cause at least part of an encrypted electronic message which has been encrypted by the message encrypting module, to be decrypted and communicated by the message communication module;

wherein the first secure data is required for the decryption of an encrypted electronic message and the security-related function comprises the decryption of an encrypted electronic message.

18. A personal electronic device according to any one of claims 13 to 17, wherein the message communication module comprises an output device for displaying an electronic message which has been decrypted.

19. A personal electronic device according to any one of claims 13 to 18, wherein the message communication module comprises a functional part of a software application which is executed on the first microprocessor in use and which outputs the decrypted electronic message to another software application which is executed on the first microprocessor.

20. A personal electronic device according to any one preceding Claim, operable to receive and store permission data which determines whether a user can cause the security-related function to occur and/or can carry out the authentication procedure.

21. A system comprising server means and a plurality of personal electronic devices according to any one preceding claim.

22. A computer readable storage medium storing computer program code which, when executed on a personal electronic device, causes the personal electronic device to function as a personal electronic device according to any one of Claims 1 to 20.

23. A memory device for removable communication with a memory interface of a personal electronic device, the memory device comprising secure memory which stores (i) first secure data which is required for a security-related function of a personal electronic device to be carried out, and (ii) second secure data which is required for an authentication procedure, wherein the memory device further comprises a microprocessor ("the second microprocessor") which controls access to the data stored in the secure memory, wherein the memory device further comprises program code which is readable on demand by a personal electronic device to which the memory device is interfaced and which, when the memory device is interfaced with a personal electronic device having a personal electronic device microprocessor ("the first microprocessor") causes the personal electronic device to function as the personal electronic device of any one of claims 1 to 20.

24. A method of regulating a security-related function of a personal electronic device which comprises a first microprocessor which controls the personal electronic device, secure memory which stores (i) first secure data which is required for a security-related function of the personal electronic device to be carried out, and (ii) second secure data which is required for an authentication procedure; and a second microprocessor which is in communication with the first microprocessor and the secure memory and which controls access to the data stored in the secure memory; the method comprising carrying out a security-related function of the personal electronic device which requires the first secure data only after the completion of an authentication procedure which requires the second secure data.

25. A computer readable storage medium storing computer program code which, when executed on a personal electronic device, causes the personal electronic device to carry out a method according to Claim 24.