A method of authenticating a user using an electronic device (100, 100'), the electronic device comprising: - a first control unit adapted to provide a processing environment having a first security level, and - a second control unit adapted to provide a processing environment having a second security level, wherein the second security level is higher than the first security level, wherein the method comprises: - receiving a candidate biometric representation; - determining, using the first control unit, a first set of biometric elements based on the candidate biometric representation; - determining, using the first control unit, a first matching level between at least a portion of the first set of biometric elements and a first biometric template stored in association with the first control unit; - forming a second set of biometric elements, wherein the second set of biometric elements comprises a selection of the first set of biometric elements, wherein the selection of the first set of biometric elements each has a first matching level above a first threshold; - determining, using the first control unit, mapping information for the second set of biometric elements, wherein the mapping information comprise geometric information relating to the second set of biometric elements; - receiving, at the second control unit, the second set of biometric elements and the mapping information; - determining, using the second control unit, a second matching level between at least a portion of the second set of biometric elements and a second biometric template stored in association with the second control unit, wherein the determination is further based on the mapping information; and - authenticating the user if the second matching level for a predetermined selection of the second set of biometric elements is above a second threshold, wherein the first biometric template comprises a first partial description of biometric features for the user, the second biometric template comprises a second partial description of corresponding biometric features for the user, the first partial description is at least partly different from the second partial description, wherein the first biometric template is a public template (Tr) and the second biometric template is a private template (Ts) and the private template comprises additional entropy as compared to the public template. - a first control unit adapted to provide a processing environment having a first security level, and - a second control unit adapted to provide a processing environment having a second security level, wherein the second security level is higher than the first security level, - receiving a candidate biometric representation; - determining, using the first control unit, a first set of biometric elements based on the candidate biometric representation; - determining, using the first control unit, a first matching level between at least a portion of the first set of biometric elements and a first biometric template stored in association with the first control unit; - forming a second set of biometric elements, wherein the second set of biometric elements comprises a selection of the first set of biometric elements, wherein the selection of the first set of biometric elements each has a first matching level above a first threshold; - determining, using the first control unit, mapping information for the second set of biometric elements, wherein the mapping information comprise geometric information relating to the second set of biometric elements; - receiving, at the second control unit, the second set of biometric elements and the mapping information; - determining, using the second control unit, a second matching level between at least a portion of the second set of biometric elements and a second biometric template stored in association with the second control unit, wherein the determination is further based on the mapping information; and - authenticating the user if the second matching level for a predetermined selection of the second set of biometric elements is above a second threshold, wherein the first biometric template comprises a first partial description of biometric features for the user, the second biometric template comprises a second partial description of corresponding biometric features for the user, the first partial description is at least partly different from the second partial description, wherein the first biometric template is a public template (Tr) and the second biometric template is a private template (Ts) and the private template comprises additional entropy as compared to the public template.