关键词: 序列密码, 密钥流的指标, 上下文随机性, 序列随机性

Abstract: Sequence Key（SK） which is a significant cryptography has attracted a lot of attention.Sequence Key specifications，Context Randomicity（CR）and Sequence Randomicity（SR），etc，are proposed to define stochastic property of sequence key，after the principle of sequence encryption being researched，and evaluation architecture is referred and proved.Weak context encryption relationship is required for sequence encryption according to CR，and CR is the intrinsic property of one time pad.SR requires weak relationship between keys from the same sequence to keep an enough huge key space.In the end，the paper concludes with an evaluation and comparison between two algorithms based on chaos and used to produce sequence key.

Key words: Sequence Key（SK）, sequence key specifications, Context Randomicity（CR）, Sequence Randomicity（SR）