fig1 shows an enrollment path of a principal prior art biometric system which will be described in the following . in this example , it is presumed that an individual wishes to enroll as a member of a chain of casinos that uses biometric identification ( using e . g . the iris 101 of an individual ) for access control . the biometric system that is employed is based on a helper data scheme ( hds ) as previously described . in order to become a member , the individual has to undergo an enrollment procedure by offering her iris to a sensor 102 arranged in an enrollment device 104 owned by the casino . although the system uses an hds by deriving enrollment data s and helper data w in an enrollment processing unit 103 and storing the data in the central storage unit 105 , and which system further does not store the biometric template of the individual , it is possible that the enrollment device has been tampered with such that the biometric template x may be eavesdropped . the individual has no way of verifying if the device 104 has been tampered with or not and although a hds is used , it is still possible that the biometric template leaks from the system , due to manipulation . although the enrollment procedure is , in many practical applications , undertaken in a controlled environment which is trusted by the individual , this is not necessarily true for the verification procedure . turning to fig2 , in order to gain access to a casino comprised in the casino chain after the enrollment is completed , the individual has to offer her biometric template y derived from her iris 201 via a sensor 202 arranged in a verification device 204 . a verification processing unit 203 fetches the helper data w stored in the central storage 205 and computes the verification data s ′ by employing a delta - contracting function . matching unit 206 compares s with s ′, and if there is a match , the identity of the individual has been verified , and the individual is given access to the casino . if there is no match , the individual is not given access to the casino . as in fig1 , the system may have been manipulated . the verification device 204 might have been tampered with such that the biometric template y is eavesdropped and again , the user has no way of controlling the verification procedure . fig3 shows a system for verification of an individual &# 39 ; s identity using biometric data associated with the individual , according to an embodiment of the present invention . the system comprises a user device 301 arranged with a sensor 302 for deriving a first biometric template x from a configuration of a specific physical feature 303 ( e . g . a fingerprint , an iris , an ear , a face etc .) of the individual , or even from a combination of physical features . the user device must be secure , tamper - proof and hence trusted by the individual . an enrollment authority 304 initially enrolls the individual in the system by storing enrollment data s in a central storage unit 305 , which enrollment data subsequently is used by a verifier 306 . the enrollment data s is secret ( to avoid identity - revealing attacks by analysis of s ) and derived , in the embodiment of fig3 at the user device 301 from the first biometric template x . at the time of verification , a second biometric template y , which typically is a noise - contaminated copy of the first biometric template x , is offered by the individual 403 to the user device 401 via the sensor 402 , see fig4 . the user device 401 generates secret verification data ( s ′) based on the second set y of biometric data and helper data w . the helper data w is based on the first set x of biometric data relates to and the enrollment data s . the helper data w is typically calculated such that s = g ( x , w ), where g is a delta - contracting function . hence , as w and s are calculated from the template x using a function or algorithm f g such that ( w , s )= f g ( x ). the verifier 406 authenticates or identifies the individual by means of the enrollment data s and verification data s ′ received from the user device 401 . noise - robustness is provided by calculating verification data s ′ at the user device 401 as s ′= g ( y , w ). the delta - contracting function has the characteristic that it allows the choice of an appropriate value of the helper data w such that s ′= s , if the second set y of biometric data sufficiently resembles the first set x of biometric data . hence , if s ′= s , verification is successful . in a practical situation , the enrollment authority may coincide with the verifier , but they may also be distributed . as an example , if the biometric system is used for banking applications , all larger offices of the bank will be allowed to enroll new individuals into the system , such that a distributed enrollment authority is created . if , after enrollment , the individual wishes to withdraw money from such an office while using her biometric data as authentication , this office will assume the role of verifier . on the other hand , if the user makes a payment in a convenience store using her biometric data as authentication , the store will assume the role of the verifier , but it is highly unlikely that the store ever will act as enrollment authority . in this sense , we will use the enrollment authority and the verifier as non - limiting abstract roles . as can be seen hereinabove , the individual has access to a device that contains a biometric sensor and is capable of computing s ′= g ( y , w ). in practice , the device could comprise a fingerprint sensor integrated in a smart card or a camera for iris or facial recognition in a mobile phone or a pda . the fact that the individual may own the user device makes it less likely that the device should be tampered with and is easier for the individual to trust . it is assumed that the individual has obtained the device from a trusted authority ( e . g . a bank , a national authority , a government ) and that she therefore trusts this device . in an embodiment of the invention , which is illustrated in fig5 , the helper data w is stored at the central storage 505 by the enrollment authority ( not shown ), fetched by the verifier 506 and sent to the user device 501 when verification is to be performed . the user device 501 then uses the helper data w received from the verifier 506 and the second template y ( which is received from the individual 503 via the sensor 502 ) to calculate the verification data s ′. thereafter , s ′ is compared with s at the verifier 506 to check for a match . in an alternative embodiment , the helper data is not stored at the central storage , but at the user device . in that case , it is not necessary that the verifier fetches the helper data and sends it to the user device , since the user device already is in possession of it . fig6 shows another embodiment of the present invention , in which embodiment the enrollment authority 604 is arranged with a sensor 602 to derive a first biometric template x from a configuration of a specific physical feature 603 of the individual . the enrollment authority 604 stores enrollment data s in a central storage unit 605 , which enrollment data subsequently is used by the verifier . the helper data w may be stored in the central storage 605 , or alternatively , as shown in fig6 , at the user device 601 . the verification is performed in the manner described hereinabove ; the verifier 606 authenticates or identifies the individual by means of the enrollment data s stored at the central storage 605 , and the verification data s ′ received from the user device 601 . if s ′= s , verification is successful . it should be noted that the secret enrollment data s and the helper data w is derived at the device with which the enrollment is effected . if the enrollment is effected at the used device as shown in fig3 , then the secret enrollment data s and the helper data w is generated at the user device . on the other hand , if the enrollment is effected at the enrollment authority as shown in fig6 , then the secret enrollment data s and the helper data w is generated at the enrollment authority . if an enrollment authority generates s and w , the individual will have to offer her template to the enrollment authority , which not necessarily is trustworthy . although the individual may trust her bank to destroy the electronic copy of the template after enrollment , she may not trust a nightclub or an internet gambling site to do the same . communication between devices may be established using any known appropriate communication channel , e . g . a wireless channel employing rf or ir transmission , or a cable employing , for example , a public switched telephone network ( pstn ). although the helper data w and the enrollment data s are generated either at the user device or the enrollment authority , and stored either at the user device or the verifier in the system described hereinabove , this is not necessarily the case . it is straightforward and obvious to a skilled person to modify the system in accordance with the present invention , such that the helper data w and the enrollment data s are generated partly at the user device and partly at the enrollment authority and may also partly be stored at the user device and partly at the verifier . it is trivial to combine some or all of the described embodiments of the present invention to arrive at such modifications . further , it is obvious to a skilled person that the data and the communications in the architectures above can be further protected using standard cryptographic techniques such as sha - 1 , md5 , aes , des or rsa . before any data is exchanged between devices ( during enrollment as well as during verification ) comprised in the system , a device might want some proof on the authenticity of another other device with which communication is established . for example , during the embodiment described in connection to fig3 , it is possible that the enrollment authority must be ensured that a trusted device did generate the enrollment data received . this can be achieved by using public key certificates or , depending on the actual setting , symmetric key techniques . moreover , in the embodiment of fig3 , it is possible that the enrollment authority must be ensured that the user device can be trusted and that it has not been tampered with . therefore , in many cases , the user device will contain mechanisms that allow the enrollment authority to detect tampering . for example , physical uncloneable functions ( pufs ) may be implemented in the system . a puf is a function that is realized by a physical system , such that the function is easy to evaluate but the physical system is hard to characterize . depending on the actual setting , communications between devices might have to be secret and authentic . standard cryptographic techniques that can be used are secure authenticated channels ( sacs ) based on public key techniques or similar symmetric techniques . also note that the enrollment data and the verification data may be cryptographically concealed by means of employing a one - way hash function , or any other appropriate cryptographic function that conceals the enrollment data and verification in a manner such that it is computationally infeasible to create a plain text copy of the enrollment / verification data from the cryptographically concealed copy of the enrollment / verification data . it is , for example possible to use a keyed one - way hash function , a trapdoor hash function , an asymmetric encryption function or even a symmetric encryption function . it is clear that the devices comprised in the system of the invention , i . e . the user device , the enrollment authority , the verifier and possibly also the central storage , is arranged with microprocessors or other similar electronic equipment having computing capabilities , for example programmable logic devices such as asics , fpgas cplds etc . further , the microprocessors executes appropriate software stored in memories , on discs or on other suitable media for accomplishing tasks of the present invention . even though the invention has been described with reference to specific exemplifying embodiments thereof , many different alterations , modifications and the like will become apparent for those skilled in the art . the described embodiments are therefore not intended to limit the scope of the invention , as defined by the appended claims .