Embodiments of the invention provide methods and apparatus for monitoring the routing configuration within an electronic device such that a biometric authentication process can be carried out without interference from other components of the device, such as may occur when the device has become infected with malware for example. The invention may provide a codec or speaker recognition processor, coupled to receive biometric input data, comprising a security module that determines whether a routing configuration complies with one or more rules. The security module may be implemented to prevent genuine biometric data from being output from the speaker recognition processor, and/or to prevent spoof biometric data from being inserted into the authentication module.