The ubiquity of wireless devices has created security concerns on the information being transferred. It is critical to protect the secret information in every layer of wireless communication to thwart any type of attacks. A dynamic reconfigurable puncturing based security mechanism, named RePunc, is proposed in this paper to provide an extra level of security at the physical layer. RePunc utilizes the puncturing feature of Forward Error Correction (FEC) to insert the secure information in the punctured positions of the standard information encoded data. The punctured patterns are dynamically changed and passed as a secret key from the sender to the receiver. An eavesdropper will not be able to detect the transmission of the secure information since the inserted secure information will be processed as channel noise by the eavesdropper's receiver. However, the rightful receiver will be able to successfully decode the secure packets by knowingly differentiating the secure information and the standard information before the FEC decoding. A case study of RePunc implementation for WiFi communication is presented in this paper, showing the extreme high security complexity with low hardware overhead.