With the intent of efficient occupying under-utilized spectrum, radio environment map (REM) based cognitive radio (CR) networking is proposed to facilitate the distributed spectrum sensing. Although the operational aspects of REM-enabled CR network are being studied actively, its security aspects have attracted very little attention. In this paper, we identify the security threats and propose generally distributed authentication architecture for REM-enabled CR networks. Furthermore, an adaptive authentication protocol (AAP) is presented. Employing channel encoding techniques and chaos sequence, authentication data is embedded into channel data as random noise. The error of host data caused by secret data can be corrected via error correcting encoding technique. The receiver can then use the secret information extracted from channel data to authenticate if the received data is sent by the user claimed. To the best of our knowledge, that is the first attempt to provide authentication me...