针对目前RFID(Radio Frequency Identification,射频识别技术)系统安全分析中忽略攻击事件对系统安全状态动态影响的问题,为了有效实现RFID系统的安全风险评估,文章提出了一种基于贝叶斯攻击图的RFID系统安全评估模型。该模型首先通过对...针对目前RFID(Radio Frequency Identification,射频识别技术)系统安全分析中忽略攻击事件对系统安全状态动态影响的问题,为了有效实现RFID系统的安全风险评估,文章提出了一种基于贝叶斯攻击图的RFID系统安全评估模型。该模型首先通过对RFID系统结构、所用协议进行分析确定系统的脆弱性漏洞及其依赖关系,建立攻击图。针对攻击图模型只能进行定性分析的问题,构建出相应的攻击图模型结构后可以结合贝叶斯理论对其进行量化。依据漏洞的利用难易度和影响程度建立RFID漏洞量化评价指标,计算出对应的原子攻击概率,然后以条件转移概率的形式将攻击节点与RFID系统的安全属性节点联系在一起,不仅能推断攻击者能够成功到达各个属性节点的风险概率,而且能够依据攻击者的不同行为动态展示系统风险状况的变化,实现评估不同状态下目标RFID系统的整体风险状况。实验表明,所提模型可以有效地计算出RFID系统整体的风险概率,为后续实施对应的安全策略提供理论依据。展开更多
λ-Carrageenan is a highly sulfated polysaccharide alternating of 1,4-O-α-D-galactopyranose-2,6-sulfate(D2S,6S)and 1,3-O-β-D-galactopyranose-2-sulfate(G2S).λ-Carrageenases are desirable tools forλ-carrageenan degr...λ-Carrageenan is a highly sulfated polysaccharide alternating of 1,4-O-α-D-galactopyranose-2,6-sulfate(D2S,6S)and 1,3-O-β-D-galactopyranose-2-sulfate(G2S).λ-Carrageenases are desirable tools forλ-carrageenan degradation.Based on the genome mining,a novelλ-carrageenase Cgl150A_Wa was cloned from the bacterium Wenyingzhuangia aestuarii and expressed in Escherichia coli.Cgl150A_Wa was an endo-acting enzyme and exhibited its maximum activity at 30℃and pH 8.0.By employing a glycomics strategy that combined ultra-performance liquid chromatography-mass spectrometry analysis and glycoinformatics,Cgl150A_Wa was proven to degradeλ-carrageenan octaose and hexaose,and the major hydrolysis product of Cgl150A_Wa wasλ-carrageenan tetrose.In addition to the typicalλ-carrageenan motifs,the active center of Cgl150A_Wa might tolerate desulfatedλ-carrageenan motifs.Cgl150A_Wa is a potential biotechnological tool for preparingλ-carrageenan oligosaccharides and structural investigation.展开更多
文摘针对目前RFID(Radio Frequency Identification,射频识别技术)系统安全分析中忽略攻击事件对系统安全状态动态影响的问题,为了有效实现RFID系统的安全风险评估,文章提出了一种基于贝叶斯攻击图的RFID系统安全评估模型。该模型首先通过对RFID系统结构、所用协议进行分析确定系统的脆弱性漏洞及其依赖关系,建立攻击图。针对攻击图模型只能进行定性分析的问题,构建出相应的攻击图模型结构后可以结合贝叶斯理论对其进行量化。依据漏洞的利用难易度和影响程度建立RFID漏洞量化评价指标,计算出对应的原子攻击概率,然后以条件转移概率的形式将攻击节点与RFID系统的安全属性节点联系在一起,不仅能推断攻击者能够成功到达各个属性节点的风险概率,而且能够依据攻击者的不同行为动态展示系统风险状况的变化,实现评估不同状态下目标RFID系统的整体风险状况。实验表明,所提模型可以有效地计算出RFID系统整体的风险概率,为后续实施对应的安全策略提供理论依据。
基金supported by the Fundamental Research Funds for the Central Universities(No.202012020)the National Key R&D Program of China(No.2018YFC 0311203).
文摘λ-Carrageenan is a highly sulfated polysaccharide alternating of 1,4-O-α-D-galactopyranose-2,6-sulfate(D2S,6S)and 1,3-O-β-D-galactopyranose-2-sulfate(G2S).λ-Carrageenases are desirable tools forλ-carrageenan degradation.Based on the genome mining,a novelλ-carrageenase Cgl150A_Wa was cloned from the bacterium Wenyingzhuangia aestuarii and expressed in Escherichia coli.Cgl150A_Wa was an endo-acting enzyme and exhibited its maximum activity at 30℃and pH 8.0.By employing a glycomics strategy that combined ultra-performance liquid chromatography-mass spectrometry analysis and glycoinformatics,Cgl150A_Wa was proven to degradeλ-carrageenan octaose and hexaose,and the major hydrolysis product of Cgl150A_Wa wasλ-carrageenan tetrose.In addition to the typicalλ-carrageenan motifs,the active center of Cgl150A_Wa might tolerate desulfatedλ-carrageenan motifs.Cgl150A_Wa is a potential biotechnological tool for preparingλ-carrageenan oligosaccharides and structural investigation.
