Complex sentence: Many of the most commonly used cryptography systems are based on the idea that the discrete log is extremely difficult to compute, and the harder it is the more secure the it is to transfer data over the internet or any other medium susceptible to interceptions of signals.
Split into simpler sentences: Many of the most commonly used cryptography systems are based on the assumption that the discrete log is extremely difficult to compute. Clearly, the more difficult it is, the more secure it is to transfer data over the internet or any other medium susceptible to interceptions of signals.