Abstract:
A personal communication apparatus is presented for generating a verifiable recording of a transaction, the transaction comprising an exchange of information. The apparatus includes a receiving component, a protection component, a memory and a recording component. The receiving component receives a transaction between a user of the apparatus and a remote person, and of receiving biometric data (BIOKY) of the remote person. The protection component protects the voice conversation with the biometric data (BIOKY). The recording component records the transaction protected with the biometric data on the memory. A communication apparatus is also presented that includes a memory and an authentication component. The authentication component provides access to a protected transaction stored on the memory.

Description:
FIELD OF THE INVENTION 
     The invention relates to a personal communication apparatus for generating verifiable data files. The invention also relates to a personal communication apparatus for verifying authenticity of data files. The invention further relates to software executable on a computing means to make the computing means capable of functioning as a personal communication apparatus for generating verifiable data files and/or for verifying authenticity of data files. 
     BACKGROUND OF THE INVENTION 
     Authentication of data files and data transfer processes is well known and of crucial importance in commerce, for example, with regard to transactions in electronic banking systems. In these banking systems, it is important to know whether or not a request to transfer money from one bank account to another is fraudulent. These transactions can potentially take the form of agreements which are often legally binding on parties involved. Similar considerations also pertain to agreements made by e-mail communication and increasingly also oral agreements. When oral agreements are made via electronic communication media, for example, via mobile telephones, authentication of the person speaking is of importance. If a given speaker can be identified unambiguously, a recording of the speaker can be potentially irrefutably verified as being authentic. 
     Published United States patent no. US2002/0107816 describes a method and system for securely recording an oral transaction. The method includes the steps of: 
     a) recording an offer and acceptance of the transaction as a digital audio file; 
     b) generating a voice security token from the recorded digital audio file; and 
     c) providing the generated voice security token to buyer and seller. 
     The voice security token has the benefit that it provides authentication of the transaction. 
     OBJECT AND SUMMARY OF THE INVENTION 
     The inventors have appreciated that voice/audio recordings can be very personal and private entities. For example, a voice recording pertaining to private matters potentially falling in the hands of a blackmailer can be used to extract money from a person generating the voice recording. However, the inventors have also envisaged that portable communication devices, for example, mobile handset telephones, will in future be equipped with considerable amounts of data storage capacity, for example, in the form of miniature optical data storage media and associated read/write drives incorporated into such communication devices. In a manner akin to e-mail communication systems, where earlier e-mail messages are stored and archived for potential later reference, it is envisaged that similar modes of operation will pertain to future mobile telephones. Thus, future mobile telephones will potentially include relatively large capacity memories of, for example, 1 Gbyte or more, including removable data carriers; for example, in future applications, mobile telephone users can potentially build complete libraries of past telephone conversations, in a manner similar to collections of written correspondence, letters and so forth. A personal communication device capable of recording a voice conversation is known from patent US2003/0032448 (‘logbook emulet’), incorporated herein by reference. Authenticity and security of past-recorded conversations recorded on data carriers is thus desirable and therefore addressed by the present invention. 
     It is an object of the invention to provide a personal communication apparatus for authenticating transactions, for example, voice conversations. 
     According to a first aspect of the invention, a personal communication apparatus is provided for generating a verifiable recording of a transaction, the transaction comprising an exchange of information, the apparatus including: 
     a) a receiving component for receiving a transaction between a user of the apparatus and a remote person, and for receiving biometric data of the remote person; 
     b) a protection component for protecting the transaction with the biometric data; 
     c) a memory for storing the protected transaction; and 
     d) a recording component for recording the transaction protected with the biometric data on the memory. 
     The invention is advantageous in that unauthorized third parties having incompatible biometric data are not able to decrypt the transaction and therefore do not have access to its content. In addition, if a third party is able to decrypt the transaction, it is proof that this party was a participant in the transaction. Biometric data cannot be easily forged and/or lost. A transaction may be, for example, a voice conversation, a video communication, or a written message. The personal communication apparatus may be, for example, a mobile phone or an add-on for a mobile phone. An add-on for a mobile phone may be physically attached to the mobile phone or may communicate with the mobile phone by using wireless technology, e.g. Bluetooth. 
     In the personal communication apparatus, the protection component is preferably capable of protecting the transaction with the biometric data by generating one or more access keys (RANKY), encrypting the transaction with the one or more access keys (RANKY), protecting the one or more access keys with the biometric data, and storing the protected one or more access keys in the memory. In this case, multiple persons can be allowed access to a single transaction without requiring the transaction to be encrypted more than once. This is especially advantageous if a transaction consists of a large data file, e.g. a voice conversation or a video communication. 
     In the personal communication apparatus, the memory preferably comprises a keylocker and the protection component is capable of storing the protected one or more access keys in the memory by storing the one or more access keys (RANKY) together with the biometric data in the keylocker. Digital rights management (DRM) systems often use a keylocker to store keys, i.e. digital rights. In these systems, a keylocker is also known as a (digital) rights locker. Only trusted DRM applications are allowed access to the keys stored in the keylocker. 
     In the personal communication apparatus, the protection component is preferably capable of protecting the one or more access keys with the biometric data by encrypting the one or more access keys (RANKY), using a biometric key (BIOKY) to generate one or more security keys (ENCKY) for use in accessing the protected voice conversation, the biometric key (BIOKY) corresponding to or being generated from the biometric data. 
     In the personal communication apparatus, the receiving component is preferably capable of receiving biometric data from a biometric measuring means which includes one or more from: fingerprint imaging of one or more digits of a human hand, analysis of phonetic content of a vocal utterance, facial imaging followed by image analysis, human iris image analysis, dental imaging, or ear contour analysis. 
     According to a second aspect of the invention, a personal communication apparatus is provided, which is operable to support authentication of a transaction therein, the transaction comprising an exchange of information, and characterized in that the apparatus includes: 
     a) a memory for storing a transaction protected with earlier biometric data; and 
     b) an authentication component for providing access to the protected transaction if biometric data measured by a biometric measuring means corresponds to the earlier biometric data. 
     In the personal communication apparatus, the authentication component is preferably capable of providing one or more access keys (RANKY) for decrypting the protected transaction, provided that the biometric data correspond to the earlier biometric data, and the personal communication apparatus preferably further includes a decrypting component for using the one or more access keys (RANKY) to decrypt at least part of the protected transaction. 
     In the personal communication apparatus, the authentication component is preferably capable of obtaining the one or more verified access keys (RANKY) by decrypting one or more security keys (ENCKY) with one or more measured biometric keys (BIOKY). 
     In the personal communication apparatus, the one or more access keys are preferably maintained in a keylocker associated therein with earlier biometric data, such that presentation of the measured biometric data to the keylocker enables access, subject to the earlier biometric data in the keylocker corresponding to the measured biometric data, to the one or more access keys (RANKY). 
     In the personal communication apparatus, the authentication component is preferably capable of receiving biometric data from a biometric measuring means which includes one or more from: fingerprint imaging of one or more digits of a human hand, analysis of phonetic content of a vocal utterance, facial imaging followed by image analysis, human iris image analysis, dental imaging, or ear contour analysis. 
     It will be appreciated that features of the invention are susceptible to any combination without departing from the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example only, with reference to the following drawings, wherein: 
         FIG. 1  is a schematic diagram of a personal communication apparatus according to the invention; 
         FIG. 2  is a flow chart relating to a method of encrypting data content (DCON) by applying a trusted component (TRCOM) utilizing a random key (RANKY) having one or more associated biometric keys (BIOKY) to generate encrypted data (ENCDCON) for storage as a data file (DFIL) on a data carrier (CAR) in a memory device (MEM); 
         FIG. 3  is a representation of a first procedure for use in the method depicted in  FIG. 2 ; 
         FIG. 4  is a representation of a second procedure for use in the method depicted in  FIG. 2 ; and 
         FIG. 5  is a flow chart of steps for recording a conversation within the apparatus of  FIG. 1 ; 
         FIG. 6  is an illustration of a key hierarchy for conversation recording in a memory of the apparatus of  FIG. 1  utilizing the first procedure (PROC 1 ) shown graphically in  FIG. 3 ; and 
         FIG. 7  is a flow chart of steps executable to decrypt an encrypted voice recording using biometric parameters in the apparatus of  FIG. 1 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An overview of the invention will be provided with reference to  FIG. 1 . In  FIG. 1 , a personal communication apparatus, for example, a mobile telephone, is denoted generally by the reference numeral  10 . The apparatus  10  includes a data-processing unit (DPU)  20  coupled to a data memory (MEM)  30 ; the processing unit  20  comprises one or more computing devices for executing software. The apparatus  10  further comprises a display device (DISP)  40 , for example, a miniature thin-film-transistor (TFT) liquid crystal display (LCD), coupled to the processing unit  20 . Moreover, the apparatus  10  comprises a radio transceiver (RX/TX)  50  connected to the processing unit  20  for transmitting and receiving wireless communications  60 . Furthermore, the apparatus  10  includes an audio interface (AINT)  70  coupled to the processing unit  20 ; the interface  70  comprises a microphone  80  and also a miniature loudspeaker or piezo-electric element  90 . The microphone  80  and loudspeaker/element  90  are used for sensing speech of a user  100  and also for generating sound for the user  100  to hear, respectively. A keypad (KY)  110  for data entry to the processing unit  20  is also included. The memory  30  is preferably implemented with a removable data carrier, most preferably at least one of a read/writable magnetic data carrier and an optical data carrier such as a SFFO optical disc as employed in Philips&#39; proprietary optical memory system “Portable Blue”. The processing unit  20  is also preferably coupled to a local memory, for example, a non-volatile read-only-memory (ROM) for storing a software operating system and one or more specific software applications for execution on the processing unit  20 . The one or more specific software applications may perform the following functions: 
     a receiving function of using the radio transceiver  50  to receive a voice conversation between a user  100  of the apparatus and a remote person, and to receive biometric data of the remote person; 
     a protection function of protecting the voice conversation with the biometric data; 
     a recording function of recording the voice conversation  240  protected with the biometric data on the memory  30 . 
     Alternatively or additionally, the one or more specific software applications may perform an authentication function of providing access to the voice conversation  240  protected with earlier biometric data and stored on the memory  30  if biometric data measured by a biometric measuring means  80  corresponds to the earlier biometric data. One of these software applications is preferably a trusted component whose operation will be described in more detail hereinafter. Alternatively to implementing the trusted component as an executable software application, it can be implemented at least in part as specific processing hardware, for example, in the form of an application specific integrated circuit (ASIC) incorporated into the apparatus  10 , the ASIC providing functionality which is extremely difficult for third parties to copy 
     Operation of the apparatus  10  will now be described with reference to  FIGS. 1 and 2 . The trusted component (TRCOM), denoted by  200  in  FIG. 2 , is used as a protection component to encrypt data content (DCON)  210  corresponding to a conversation or oral transaction by processing the data content  210 , using a random encryption key (RANKY)  220  to generate corresponding encrypted data content (ENCDCON)  230 . Subsequently, the encrypted data content (ENCDCON)  230  is stored as a data file (DFIL)  240  on a data carrier (CAR)  250  of the memory  30  by the recording component. The trusted component (TRCOM)  200  is employed to associate (ASSOC) one or more biometric keys (BIOKY)  260  of each participant involved in the conversation or oral transaction with the random key (RANKY)  220 . Such an association (ASSOC) can be implemented by means of first or second procedures, as will now be described. 
     In the first procedure (PROC 1 ) depicted in  FIG. 3 , the trusted component (TRCOM)  200  securely receives the one or more biometric keys (BIOKY)  260 . The component (TRCOM)  200  is able to encrypt the aforementioned random key (RANKY)  220  to generate a corresponding encrypted random key (ENCKY)  300 , which encryption utilizes the one or more biometric keys (BIOKY)  260 . Moreover, the component (TRCOM)  200  is also able to act as an authentication component to decrypt the encrypted random key (ENCKY)  300  with any one of the one or more biometric keys (BIOKY)  260 . Only the encrypted random key (ENCKY)  300  is eventually stored in the memory (MEM)  30  shown in  FIG. 1 . The first procedure (PROC 1 ) has the benefit that it is not necessary for the encrypted random key (ENCKY)  300  to be stored in a secure memory, for example, in a “keylocker” for achieving enhanced security; namely, the encrypted random key (ENCKY)  300  can be stored in a standard memory (STNMEM), which is not necessarily designated as “keylocker” memory, while yet maintaining security. 
     In the second procedure (PROC 2 ) depicted in  FIG. 4 , the trusted component (TRCOM)  200 , acting as a protection component, securely receives the one or more biometric keys (BIOKY)  260  and then stores them securely in a keylocker (KYLCK)  330  together with the random key (RANKY)  220 . The keylocker (KYLCK)  330  is a secure storage facility for storing keys. Moreover, the trusted component (TRCOM)  200  is also capable of associating (ASSOC) the random key (RANKY)  220  with the one or more biometric keys (BIOKY)  260  stored in the keylocker (KYLCK)  330 . The trusted component (TRCOM)  200  is operable only to retrieve (RTR) a random key, for example, the random key (RANKY)  220 , from the keylocker (KYLCK)  330  if the component (TRCOM)  200  is able to supply to the keylocker (KYLCK)  330  any one of the one or more biometric keys (BIOKY)  260  corresponding to the random key (RANKY)  220  stored in the keylocker (KYLCK)  330 . 
     Recovery of the random key (RANKY)  220  enables the data file (DFIL)  240  to be authenticated, for example, by allowing the file (DFIL)  240  to be decrypted, using the random key (RANKY)  260 . 
     The inventors have appreciated that the use of biometric keys is important to implement the method of the invention for achieving authentication. “Biometric” is to be interpreted as “measurement of some biological feature”, for example, one or more of: 
     a) characteristic voice phonetic details; 
     b) facial spatial feature details, such as aspect ratio of nose, mouth to forehead; 
     c) fingerprint details; 
     d) iris details; 
     e) dental details, such as spatial aspect ratio of front incisor teeth; and 
     f) ear (pinna) spatial profile details, 
     but is not limited to these examples. The use of phonetic voice details is most preferred on account of the apparatus  10  already including a microphone  80  to transduce the user&#39;s  100  voice and processing capacity in the data-processing unit (DPU)  20  to execute necessary voice signal data processing to extract corresponding biometric parameters and thereby derive the biometric keys (BIOKY)  260  when the authentic user  100  is using the apparatus  10 . Beneficially, the apparatus  10  includes a miniature digital camera coupled to the data-processing unit (DPU)  20  for generating the biometric keys (BIOKY)  260 . Biometric keys have the advantage that they are an inseparable part of the user  100  and hence are not susceptible to being easily copied or lost. However, the current popularity of plastic surgery can render biometric authentication potentially less reliable, for example, facial details are susceptible to being modified by face lifts, lip implants, rhinoplasty, blepharoplasty and/or cranial orbital bone grind. Moreover, fingerprints are susceptible to being modified by scarring events (lesions), skin surface abrasion and skin grafts. However, problems associated with using such biometrics can be alleviated by using more than one biometric key for each user, for example, by using a fingerprint-derived key in combination with an iris-derived key. Measurement of each biometric key is not required whenever such a plurality of biometric keys is employed, because a keylocker can be configured to store associations of one biometric key with another. 
     The random key (RANKY)  220  is preferably dynamically altered from one sound recording to another so that not all recordings are compromised if one random key (RANKY)  220  relating to files stored in the memory (MEM)  30  is discovered by a third party. A temporal starting instance of a sound recording to be stored in the memory (MEM)  30  can be beneficially used as a random seed for generating the random key (RANKY)  220 . Alternatively, spatial location of the apparatus  10  when recording a conversation in the memory (MEM)  30 , for example, as determined by the apparatus  10  receiving geographical co-ordination references from the nearest mobile telephone radio mast, is also susceptible to being used as a seed for generating the random key (RANKY)  220 . As a further alternative, a combination of temporal and geographical input can be used to generate the random key (RANKY)  220 . 
     The random key (RANKY)  220  is preferably applied by the processing unit (DPU)  20  to encrypt a conversation from the user  100  in real time so that a partially unencrypted file is not inadvertently recorded in the memory (MEM)  30 . When completing a conversation using the apparatus  10 , the apparatus  10  preferably prompts the remote person, and optionally the user  100 , to input his unique access key, for example, the remote person&#39;s fingerprint, the remote person&#39;s utterance of a reference phrase for phonetic authentication, or a view of the remote person&#39;s face, for example, for purposes of generating the biometric key (BIOKY)  260 . 
     In a situation where a remote person wants to access one of the recordings stored in the memory (MEM)  30 , for example, by telephoning to the user  100  where the user  100  has recorded a transaction in the memory (MEM)  30 , the remote person can potentially access the recording, provided that the remote user has a biometric key included within the one or more biometric keys (BIOKY)  260 . The biometric key from the remote person can potentially be sent as an encrypted mobile telephone message from the remote person to the apparatus  10 . The apparatus  10  can be arranged to support several biometric keys for multiple remote persons for accessing conversations of the user  100  stored in the memory (MEM)  30 . 
     When the user  100  wants to refer back to an earlier conversation recorded by the apparatus  10  in its memory (MEM)  30 , the apparatus  10  is preferably programmed in such a way that its processing unit (DPU)  20  reminds the user  100  of presenting his biometric parameter, for example, by offering a finger to the apparatus for fingerprint reading, or by uttering a special phrase which the processing unit  20  is operable to analyze, for example, by way of temporal spectral analysis, the apparatus  10  thereby being able to derive a biometric parameter for generating a biometric key to allow the user  100  access to a data file stored in the memory (MEM)  30  corresponding to the conversation. 
       FIG. 5  is a flow chart of a method, proposed by the inventors, for recording conversation onto a mobile data medium. Mnemonics and method steps are to be interpreted with reference to Table 1. 
     
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Step 
                 Mnemonic 
                 Interpretation 
               
               
                   
               
             
             
               
                 400 
                 CllPtThru 
                 Call is put through 
               
               
                 410 
                 GetTimLocInfmNet 
                 Get time/location information from network 
               
               
                 420 
                 GenEncKy1frmTimLocInfm 
                 Generate encryption key Key 1 from the time/location information 
               
               
                 430 
                 EncConwthEncKy1 
                 Encrypt the conversation with the encryption key Key 1 
               
               
                 440 
                 WllConEnd? 
                 Will the conversation end? 
               
               
                 450 
                 SavEncConBdDat 
                 Save end encrypted conversation body data to memory (MEM) 30 
               
               
                 460 
                 GetFng/Vce 
                 Get fingerprint via embedded fingerprint scanner in the apparatus 10 or 
               
               
                   
                   
                 voice fingerprint via the apparatus 10 itself; if required, a remote speaker can 
               
               
                   
                   
                 also send his scanned fingerprint/voice fingerprint via a wireless network 
               
               
                 470 
                 HashFngVceGenEncKy2 
                 Hash the fingerprint/voice fingerprint to generate an encryption key Key 2 
               
               
                 480 
                 EncKy1wthKy2GenFng/Vce 
                 Encrypt the Key 1 using the Key 2 to generate corresponding encrypted Key 1 
               
               
                 490 
                 StEncKy1inMem 
                 Store the encrypted Key 1 in the memory (MEM) 30 
               
               
                   
               
             
          
         
       
     
     In a step  400 , a telephone call is connected through from the apparatus  10  to a communication network. Thereafter, in a step  410 , the apparatus  10  is supplied from the communication network with at least one of time-of-call information and geographical location information to act as a seed for generating the random encryption key (RANKY)  220 . Subsequently, in a step  420 , the processing unit (DPU)  20  generates the random key (RANKY)  220 , namely Key  1 , from at least one of the time-of-call and the location information. In a step  430 , the apparatus  10  assimilates the call while the user  100  is generating it and encrypts it in real time. Thereafter, in a step  440 , the apparatus  10  checks whether or not the call has ended. If the call has not yet ended, the apparatus  10  continues executing the step  430 . Conversely, if the call is found to have ended in step  440 , the apparatus  10  progresses to a step  450  wherein the processing unit (DPU)  20  is operable to save an encrypted body of the conversation onto the data carrier (CAR)  250  in the memory (MEM)  30 . In a step  460 , the apparatus  10  obtains a biometric fingerprint, for example, an image of an actual fingerprint derived via an embedded fingerprint scanner included within the apparatus  10  and connected to the processing unit (DPU)  20 , or a biometric analysis “fingerprint” of an acoustic voice signal obtained, using the microphone  80 . Additionally, or alternatively, the apparatus  10  receives one or more remote fingerprints from a remote speaker via the communication network. Moreover, in a step  470 , the fingerprint is processed to generate the one or more biometric keys (BIOKY)  260 , namely Key  2 . Furthermore, in a subsequent step  480 , the random key (RANKY)  220 , namely key  1 , is encrypted with the one or more biometric keys (BIOKY)  260  to generate a corresponding encrypted key (ENCKY)  300 . Finally, in a step  490 , the apparatus  10  stores its encrypted key (ENCKY)  300  in the memory (MEM)  30 . The flow chart in  FIG. 5  thus utilizes the aforementioned first procedure (PROC 1 ). 
       FIG. 6  illustrates a key hierarchy for conversation recording in the memory (MEM)  30  in accordance with the first procedure (PROC 1 ) shown graphically in  FIG. 3 . Mnemonics used in  FIG. 6  have the same meanings as in Table 2. 
     
       
         
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Step 
                 Mnemonic 
                 Interpretation 
               
               
                   
               
             
             
               
                 500 
                 RlTimConDat 
                 Real time conversation data 
               
               
                 510 
                 EncConKy1 
                 Encrypt the conversation with Key 1 
               
               
                   
                   
                 (RANKY) 
               
               
                 520 
                 Tim/LocInRnKy 
                 Time/Location Information/Random Key 
               
               
                 530 
                 GenEncKy1 
                 Generate encryption key Key 1 (RANKY) 
               
               
                 540 
                 EncConDatSc 
                 Encrypted conversation data sector 
               
               
                 550 
                 InptFng/Vce 
                 Input fingerprint/voice “fingerprint” 
               
               
                 560 
                 Hsh 
                 Hash function 
               
               
                 570 
                 GenKy2forKy1Enc 
                 Generate biometric key (BIOKY), namely 
               
               
                   
                   
                 Key 2 
               
               
                 580 
                 EncKy1wthKy2 
                 Encrypt Key 1 with Key 2 
               
               
                 590 
                 EncKy1inKyLck 
                 Encrypted Key 1 stored (for example, in 
               
               
                   
                   
                 keylocker) 
               
               
                   
               
             
          
         
       
     
     Moreover,  FIG. 7  shows a flow chart of a method of retrieving a conversation recorded within the apparatus  10 . Mnemonics employed in  FIG. 7  have the same meanings as in Table 3. 
     
       
         
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 Step 
                 Mnemonic 
                 Interpretation 
               
               
                   
               
             
             
               
                 600 
                 InpFing/Vce 
                 Input Fingerprint/Voice 
               
               
                   
                   
                 “fingerprint” 
               
               
                 610 
                 Hsh 
                 Hash function 
               
               
                 620 
                 GenCanKy2 
                 Generate candidate key Key 2 
               
               
                 630 
                 DecKy1byKy2forCanKy1 
                 Decrypt encrypted Key 1 
               
               
                   
                   
                 (ENCKY) using Key 2 (BIOKY) 
               
               
                   
                   
                 for generating candidate Key 1 
               
               
                 640 
                 DecVceDatawthCanKy1 
                 Decode voice data stored in the 
               
               
                   
                   
                 memory (MEM) 30 using the 
               
               
                   
                   
                 candidate decryption Key 1 to 
               
               
                   
                   
                 generate decrypted data 
               
               
                 650 
                 CckDecDataPlybyFone 
                 Check whether or not the 
               
               
                   
                   
                 decrypted data can be played 
               
               
                   
                   
                 on the apparatus 10 
               
               
                 660 
                 Cont 
                 Continue 
               
               
                 670 
                 NoVldUse/stp 
                 Not a valid user, stop 
               
               
                   
               
             
          
         
       
     
     In  FIG. 7 , biometric parameters are measured in a step  600  and then processed by a hash function in a step  610  to generate a candidate Key  2 , namely a candidate biometric key (BIOKY), in a step  620 . Subsequently, in a step  630 , the processing unit (DPU)  20  attempts to apply the candidate Key  2  to decrypt the encrypted Key  1  (ENCKY) to generate a corresponding candidate Key  1  (candidate RANKY). Thereafter, in a step  640 , the processing unit (DPU)  20  attempts to decode encrypted voice data stored in the memory (MEM)  30  using the candidate Key  1 . The apparatus  10  checks, in a step  650 , at the processing unit (DPU)  20  that the voice data is susceptible to being decrypted, using the candidate Key  1 . If the decryption of the data is unsuccessful, the apparatus  10  interprets this as incorrect biometric data gathered in the step  600 , for example, an unauthorized third party trying to gain access to the data. In such a situation, the processor unit (DPU)  20  proceeds to a step  670 . Conversely, if the data can be successfully decoded, using the candidate Key  1 , the processing unit (DPU)  20  continues its data decoding operation in step  640  until a desired portion of the data has been decoded. 
     Numerals and symbols within parentheses in the accompanying claims are solely intended to aid understanding of the claims and are not intended in any way to affect their scope. 
     It will be appreciated that embodiments of the invention described in the foregoing can be modified without departing from the scope of the invention as defined by the accompanying claims. 
     The use of verbs such as “comprise”, “include”, “incorporate”, “contain”, “be” and “have” and their conjugations is to be construed in a non-exclusive manner when interpreting the description and its associated claims, namely to allow presence of other items or components which are not explicitly defined. Reference to singular use is also to be construed to be reference to plural use, and vice versa. 
     ‘Software executable’ is to be understood to mean any software product stored on a computer-readable medium, such as a floppy disk, downloadable via a network, such as the Internet, or marketable in any other manner.