We design and implement a cryptographic biometric authentication system using a microcoded architecture. The secure properties of the biometric matching process are obtained by means of a fuzzy vault scheme. The algorithm is implemented in a reprogrammable, microcoded coprocessor called FV16. We present the micro-architecture of FV16 as well as a dedicated assembler for this architecture. Our coprocessor can be attached to an ARM processor, and offers a 83-fold cycle count improvement when the fuzzy vault algorithm is migrated from embedded ARM software (13.8 million cycles) to the FV16 coprocessor (166 thousand cycles). Categories and Subject Descriptors