*CSS Chapter 1*Cryptography and Network SecurityChapter 1 Introduction

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Background*CSS Chapter 1*Information security requirements have changed in recent timesTraditionally provided by physical and administrative mechanismsComputer use requires automated tools to protect files and other stored informationUse of networks and communications links requires measures to protect data during transmission

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Definitions*CSS Chapter 1*Computer Security - generic name for the collection of tools designed to protect data and to thwart hackersNetwork Security - measures to protect data during their transmissionInternet Security - measures to protect data during their transmission over a collection of interconnected networks

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Aim of Course*CSS Chapter 1*Our focus is on internet securityWhich consists of measures to deter, prevent, detect, and correct security violations that involve the transmission & storage of information

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Security Trends*CSS Chapter 1*

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OSI Security Architecture*CSS Chapter 1*Itu-t x.800 security architecture for OSIDefines a systematic way of defining and providing security requirementsFor us it provides a useful, if abstract, overview of concepts we will study

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Aspects of Security*CSS Chapter 1*Consider 3 aspects of information security:Security attackSecurity mechanismSecurity service

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Security Attack*CSS Chapter 1*Any action that compromises the security of information owned by an organizationInformation security is about how to prevent attacks, or failing that, to detect attacks on information-based systemsOften threat & attack used to mean same thingHave a wide range of attacksCan focus of generic types of attacksPassiveActive

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Passive Attacks*CSS Chapter 1*

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Active Attacks*CSS Chapter 1*

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Security Service*CSS Chapter 1*Enhance security of data processing systems and information transfers of an organizationIntended to counter security attacksUsing one or more security mechanisms Often replicates functions normally associated with physical documentsWhich, for example, have signatures, dates; need protection from disclosure, tampering, or destruction; be notarized or witnessed; be recorded or licensed

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Security Services*CSS Chapter 1*X.800:a service provided by a protocol layer of communicating open systems, which ensures adequate security of the systems or of data transfers

RFC 2828:a processing or communication service provided by a system to give a specific kind of protection to system resources

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Security Services (X.800)*CSS Chapter 1*Authentication - assurance that the communicating entity is the one claimedAccess Control - prevention of the unauthorized use of a resourceData Confidentiality protection of data from unauthorized disclosureData Integrity - assurance that data received is as sent by an authorized entityNon-Repudiation - protection against denial by one of the parties in a communication

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Security Mechanism*CSS Chapter 1*Feature designed to detect, prevent, or recover from a security attackNo single mechanism that will support all services requiredHowever one particular element underlies many of the security mechanisms in use:Cryptographic techniquesHence our focus on this topic

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Security Mechanisms (X.800)*CSS Chapter 1*Specific security mechanisms:Encipherment, Digital Signatures, Access Controls, Data Integrity, Authentication Exchange, Traffic Padding, Routing Control, NotarizationPervasive security mechanisms:Trusted Functionality, Security Labels, Event Detection, Security Audit Trails, Security Recovery

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Model for Network Security*CSS Chapter 1*

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Model for Network Security*CSS Chapter 1*Using this model requires us to: Design a suitable algorithm for the security transformation Generate the secret information (keys) used by the algorithm Develop methods to distribute and share the secret information Specify a protocol enabling the principals to use the transformation and secret information for a security service

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Model for Network Access Security*CSS Chapter 1*

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Model for Network Access Security*CSS Chapter 1*Using this model requires us to: Select appropriate gatekeeper functions to identify users Implement security controls to ensure only authorised users access designated information or resources Trusted computer systems may be useful to help implement this model

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Summary*CSS Chapter 1*Have considered:Definitions for: Computer, network, internet securityX.800 standardSecurity attacks, services, mechanismsModels for network (access) security

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