Handshake retransmission is the DTLS mechanism that resends handshake messages when packets are lost, delayed, or reordered. Because DTLS runs over unreliable datagram networks such as UDP, this recovery logic is essential for completing a secure session without TCP-style delivery guarantees.
In cyber security, retransmission matters because it sits at the boundary between protocol resilience and memory safety. Attackers may try to trigger unusual resend states, interrupted writes, or boundary errors in the code that tracks handshake progress. If that logic is flawed, a peer may receive unintended bytes, or the process may crash, creating data leakage or denial-of-service risk. Defenders focus on patching affected libraries, testing DTLS state machines under packet loss, and validating that retransmit handling correctly preserves buffer boundaries and offsets.