A method comprising: receiving public values of a plurality of mobile devices (104, 220, 222, 224) within a proximity vicinity of an access device, and storing the public values of the plurality of mobile devices (104,220,222,224), wherein the plurality of mobile devices (104, 220, 222, 224) comprises a first mobile device; obtaining, by the access device, a first biometric sample of a user; generating a first biometric template from the first biometric sample; for each mobile device of the plurality of mobile devices (104, 220, 222, 224) within the proximate vicinity of the access device: retrieving a public value of the mobile device from the stored public values, wherein: the public value of the mobile device was generated by passing a biometric template of the mobile device to a first function of a fuzzy extractor; and the biometric template of the mobile device was generated from a biometric sample of the mobile device; generating a secret cryptographic key by passing the first biometric template and the public value of the mobile device to a second function of the fuzzy extractor; encrypting the first biometric template with the secret cryptographic key; and broadcasting the encrypted first biometric template to the plurality of mobile devices (104, 220, 222, 224); receiving, from the first mobile device, a confirmation of a match between the first biometric template and a biometric template of the first mobile device, wherein the biometric template of the first mobile device is generated from a biometric sample of the first mobile device; and responsive to the confirmation, conducting a transaction between the access device and the first mobile device. receiving public values of a plurality of mobile devices (104, 220, 222, 224) within a proximity vicinity of an access device, and storing the public values of the plurality of mobile devices (104,220,222,224), wherein the plurality of mobile devices (104, 220, 222, 224) comprises a first mobile device; obtaining, by the access device, a first biometric sample of a user; generating a first biometric template from the first biometric sample; for each mobile device of the plurality of mobile devices (104, 220, 222, 224) within the proximate vicinity of the access device: retrieving a public value of the mobile device from the stored public values, wherein: the public value of the mobile device was generated by passing a biometric template of the mobile device to a first function of a fuzzy extractor; and the biometric template of the mobile device was generated from a biometric sample of the mobile device; generating a secret cryptographic key by passing the first biometric template and the public value of the mobile device to a second function of the fuzzy extractor; encrypting the first biometric template with the secret cryptographic key; and broadcasting the encrypted first biometric template to the plurality of mobile devices (104, 220, 222, 224); retrieving a public value of the mobile device from the stored public values, wherein: the public value of the mobile device was generated by passing a biometric template of the mobile device to a first function of a fuzzy extractor; and the biometric template of the mobile device was generated from a biometric sample of the mobile device; the public value of the mobile device was generated by passing a biometric template of the mobile device to a first function of a fuzzy extractor; and the biometric template of the mobile device was generated from a biometric sample of the mobile device; generating a secret cryptographic key by passing the first biometric template and the public value of the mobile device to a second function of the fuzzy extractor; encrypting the first biometric template with the secret cryptographic key; and broadcasting the encrypted first biometric template to the plurality of mobile devices (104, 220, 222, 224); receiving, from the first mobile device, a confirmation of a match between the first biometric template and a biometric template of the first mobile device, wherein the biometric template of the first mobile device is generated from a biometric sample of the first mobile device; and responsive to the confirmation, conducting a transaction between the access device and the first mobile device.