Security has long been a challenging problem in wireless networks mainly due to its broadcast nature of the communication. It opens up simple and yet effective measures to thwart useful communications between legitimate radios. Spread spectrum technologies such as direct sequence spread spectrum (DSSS) have been developed as effective countermeasures against, for example, jamming attacks. This paper surveys previous research on securing a DSSS channel even further using physical layer attributes - Keyless DSSS mechanisms and Watermarked DSSS (WDSSS) schemes. The former has been motivated by the fact that it is still an open question to establish and share the secret spread sequence between the transmitter and the receiver without being noticed by adversaries. The basic idea of the latter is to exploit the redundancy inherent in DSSS’s spreading process to embed watermark information. It can be considered a counter measure (authentication) for an intelligent attacker who obtains the spread sequence to generate fake messages. This paper also presents and evaluates an adaptive DSSS scheme that takes both jam resistance and communication efficiency into account