We propose a systematic concatenated coding scheme based on the combination of interleaving with powerful channel codes for wireless secrecy at a reduced energy cost. The basic idea lies in generating a short random key that is used to shuffle/interleave information at the source. This key is then sent to the legitimate receiver during a brief period of advantageous communication over the eavesdropper (e.g. due to more interference from a jammer). Finally, the key is decoded at the legitimate receiver to properly deinterleave the original information. Bob receives a better quality version of the interleaving key, therefore providing the needed advantage over the eavesdropper. A strong inner code provides reliability of data, while a shorter outer code provides extra error protection for the interleaving key. We propose a methodology for selection of the outer key code with reliability and security constraints. For that, we introduce a bit error complementary cumulative distribution function metric, that is suitable for security and reliability analysis of t-error correcting codes. Wireless secrecy comes from using interleaving for secrecy purposes rather than for reliability alone.