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The Fall of One, the Rise of Many: A Survey on Multi-Biometric Fusion Methods

Increasing operational and security demands changed biometrics by shifting the focus from single to multi-biometrics. Multi-biometrics are mandatory in the current context of large international biometric databases and to accommodate new emerging security demands. Our paper is a comprehensive survey on multi-biometrics, covering two important topics related to the multi-biometric field: fusion methods and security. Fusion is a core requirement in multi-biometric systems, being the method used to combine multiple biometric methods into a single system. The fusion section surveys recent multi-biometric schemes categorized from the perspective of fusion method. The security section is a comprehensive review of current issues, such as sensor spoofing, template security, and biometric encryption. New research trends and open challenges are discussed, such as soft, adaptive contextual-based biometrics. Finally, an implementation blueprint for a multi-biometric system is presented in the form of a list of questions to be answered when designing the system.