Abstract: Key extraction is the propitious technique to create a protected key between the users over the OFDM subcarrier. This study present a new perspective for extraction of key securely and efficiently with adaptive filtration for OFDM system. The efficiency is accomplished by the totally exploiting randomness from frequency and time domain and cross correlation of channel measurements. The system can be classified in terms of Key Generation Rate (KGR), Key Disagreement Rate (KDR) and key randomness. RLS adaptive filter is introduced for better noise reduction in OFDM sub carriers and improves convergence speed.