Text encryption using Sosemanuk and Harris Hawks optimization by laser communication.

The growth of the Internet of Things and embedded devices requires increasing the secure and energy-efficient communication protocols, whereas conventional cryptographic algorithms usually tend to be out of the computational capability of these resource-constrained devices. This paper suggests a lightweight encryption combining cryptographic security and physical layer encoding using the Sosemanuk stream cipher, which is statistically optimized session-dependent key candidates produced by the Harris Hawks Optimization algorithm. The ensuing encrypted message is then encoded to International Morse code that is used to modulate a laser diode to facilitate optical wireless communications. The optical Morse signal is decoded by a complementary receiver with a light-dependent resistor, which verifies the message's authenticity by a Hash-based Message Authentication Code. The analysis of security indicates that the system has a high level of randomness, and the avalanche effect is 50.35% with a low bit dependency criterion correlation of 0.0366 using selected NIST SP 800 - 22 statistical tests. The metrics of performance indicate the efficiency of the computational ability of the system, with an encryption throughput of 82.78 KB/s, which is feasible and provides a secure solution to low-power devices.