New Encryption Method with Very Long Keys for QKD and RKD

Source abstract

Established symmetric encryption schemes rely on short key lengths, typically between 128 and 256 bits. However, well-known physical key exchange schemes such as QKD (Quantum Key Distribution) and RKD (Radio Signal Key Distribution) generate megabits of new key material on a daily, weekly, or other basis. This article presents a new encryption scheme, called OTPH, which was specifically designed for these megabits of regularly generated new key material. In this scheme, the key material is treated as an extremely long key, and the key’s enormous entropy is fully exploited. OTPH first uses a bit-selection procedure that randomly selects bits from the circularly arranged key, thereby extending the key many times over. From this, a HKDF (Hash Key Derivation Function) derives many new keys, and the result is a bit sequence that serves as the key for encryption using an XOR operation. OTPH uses only the XOR operation and hash function, which are also used in QKD and RKD during postprocessing (albeit a different hash function). An initial cryptanalysis has also been performed for OTPH. OTPH operates in a manner entirely contrary to established methods. It requires a completely new perspective. OTPH will not compete with AES, ChaCha20 etc., but will instead be used primarily in the context of QKD and RKD.