  Direct-sequence spread spectrum (DSSS) has been recognized as an effective
jamming resilient technique. However, the effectiveness of DSSS relies on the
use of either pre-shared unique secret keys or a bank of public codes, which
can be prohibitively expensive in future large-scale decentralized wireless
networks, e.g., the Internet of Things. To tackle this problem, in this work we
develop a new framework for self-controlled physical-layer-security-based
spreading sequence generation. Specifically, we exploit the shared randomness
inherent in wireless channels to generate and refresh secret seeds at each
communicating node using shared randomness extraction, entropy pooling and
random seed generation. The generated secret seeds are then utilized to perform
DSSS. To evaluate the performance, we implement our framework on software
defined radio platform and examine the successful transmission probability of
the system under various models of broadband jamming along with an special case
wherein adversary is assumed to have leaked information on key rate. Both our
analysis and real-world measurements confirm that communication systems based
on our framework can achieve jamming-resilient communications without requiring
pre-shared sequences.
