关键词: 公钥密码体制, 基于编码的密码体制, 后量子密码学

Abstract:

TCHo is short for “Trapdoor Cipher, Hardware Oriented” . It is a code-based public-key cryptosystem which is inspired by fast correlation attack. TCHo cryptosystem can resist the attacks from quantum computers which is a post-quantum cryptosystem. An early version was proposed in 2006 by Finiasz and Vaudenay with non-polynomial (though practical) decryption time. The later version came in 2007 with more co-authors. It reached competitive (heuristic) polynomial complexity and IND-CPA security. In 2013, Alexandre and Serge introduces the TCHo cryptosystem in Advances in Network Analysis and its Applications. The security of the cryptosystem relies on the hardness of finding a multiple polynomial with low weight and on the hardness of distinguishing between the out of the LFSR with noise and some random sources, hence, the parameter selection of this cryptosystem determines the security and reliability. This paper introduces the TCHo cryptosystem in detail and analyzes the parameter selection. This paper also points out the condition of achieving the only decoding and discusses the calculation formula for measuring the reliability level of the cryptosystem. At the same time, a method of parameter selection is presented so that the cryptosystem is more reliable.

Key words: public-key cryptosystem, code-based cryptosystem, post-quantum cryptography