A public key cryptosystem based on a new principle that is difficult to decipher even with a quantum computer was developed through joint research by Hokkaido Kyoiku University, Kyushu University, Industrial Technology Research Institute, and Toshiba Corporation.It is a configuration based on the minimum solution problem of nonlinear indefinite equations, which is expected to be difficult to calculate even with a quantum computer, and it is expected to be as secure and computationally efficient as the lattice-based cryptography that has been considered to be influential in this area. ..
Currently, the development of quantum computers is progressing at a rapid pace due to the large-scale investment of major IT companies and the government.When a quantum computer is developed, the prime factorization and discrete logarithm problems that the current public key cryptography is based on are solved in a short time, and the cipher is broken, so it is difficult to break even with a quantum computer. Research and development of quantum public key cryptography has been actively carried out in recent years.However, anti-quantum public key cryptography has the drawback of having a large public key size, and has not been put into practical use until now.
What was developed this time is a new method that seeks the basis of security for the problem of solving nonlinear equations, which is more difficult to calculate than the problem of solving linear equations that the conventional anti-quantum public key cryptography has used as the basis of security. method.As a result, the powerful solution that could be applied to the linear equation can no longer be directly applied, and improvement in safety can be expected.In addition, the public key size, which has been an issue, can be secured at the same level as the improved lattice-based cryptography (about 2KB).
Toshiba says that it will continue to improve with the aim of proposing the international standardization of this public key cryptography while receiving security evaluations at international conferences and the like.If security can be realized with a public key as short as the current public key cryptography by future improvements, it will be possible to pave the way for practical use and realize a long-term secure network that can withstand the emergence of quantum computers.