抄録
We improve our former implementation of key generation for a cryptosystem OTU2000 with resistance to quantum computers. First, we give a polynomial time algorithm to determine a prime number satisfying a secret key condition. Next, on another secret key condition to guarantee the uniqueness of decoding, we prove a weaker sufficient condition than that in original OTU2000 and give an algorithm by this new condition. These allow us to choose secret keys from more combinations than before. Experimental results including our improvements are also shown. This will lead us to use OTU2000 without quantum computers.
