NTRU加密算法的一类弱密钥研究

Research on weak key of NTRU encryption scheme

分析了NTRU公钥加密算法的一类弱密钥。根据NTRU所涉及的CS格与循环码的生成矩阵结构相似的特点,指出当NTRU的公钥与(xn-1)的最大公因式的次数大于零时,CS格的生成矩阵不可逆,此时可用类似于循环码译码的方法和格基归约算法破解NTRU。最后给出了能使NTRU避免生成此类弱密钥的方法。

This paper analyzed a class of weak keys of NTRU. According to the similarity between the structures of the CS lat- tice in NTRU and the generation matrix of cyclic code, when the degree of the greatest common divisor of NTRU public key and （xn - 1 ） was great than zero, generation matrix of CS lattice was not reversible and NTRU could be broken by the deco- ding technique of cyclic code and lattice reduction algorithm. Finally it proposed a method to protect NTRU against this flaw.