关键词: 密码学, 密钥协商, 三角矩阵, 密码分析, 非阿贝尔群

Abstract: Key agreement is an important mean to realize the secure communication between participants under the open and fair environment. Recently, Alvarez et al proposes a novel key agreement protocol, the session key in this protocol is generated by multiplying powers of block triangular matrices. The research in this paper finds that the original protocol is insecure since that the security parameter in Alvarez’s scheme can be obtained by solving a set of linear equations, it analyzes this protocol carefully and proposes a novel practical attack method. It is worth mentioning that this attack method can be used in the similar key agreement protocols based on the block triangular matrices technology.

Key words: cryptography, key agreement, triangular matrix, cryptanalysis, non-Abelian group