Chapter- I introduction
- 1. NETWORK SECURITY Name of the Staff : M.FLORENCE DAYANA M.C.A.,M.Phil.,(Ph.D)., Head, Dept. of CA Bon Secours College For Women Thanjavur. Class : II MSc., CS Semester : III Unit : I 2/15/2019 1
- 2. ELECTIVE III – NETWORK SECURITY Unit I Overview-Symmetric Ciphers: Classical Encryption Techniques Unit II Symmetric Ciphers: Block ciphers and the Data Encryption Standards Public key Encryption and Hash Functions: Public-Key Cryptography and RSA Unit III Network Security Practices: Authentication applications-Electronic Mail Security Unit IV Network Security Practices: IP Security-Web Security Unit V System Security: Intruders-Malicious Software-Firewalls Text Book(s) 1. William Stallings, Cryptography and Network Security- Principles and Practices, Prentice-Hall, Third edition, 2003 References 1. Johannes A. Buchaman , Introduction to cryptography, Springer-Verlag. 2. Atul kahate , Cryptography and Network Security, TMH
- 3. Definitions • Computer Security - also known as cyber security or IT security, is the protection of computer systems from the theft or damage to their hardware, software or information, as well as from disruption or misdirection of the services they provide. • Network Security - measures to protect data during their transmission
- 4. • Internet Security - measures to protect data during their transmission over a collection of interconnected networks. • which consists of measures to deter, prevent, detect, and correct security violations that involve the transmission & storage of information
- 5. 5 Goals of Computer Security
- 6. 1.CONFIDENTIALITY • Confidentiality refers to protecting information from being accessed by unauthorized parties. In other words, only the people who are authorized to do so can gain access to sensitive data. • Imagine your bank records. You should be able to access them, of course, and employees at the bank who are helping you with a transaction should be able to access them, but no one else should.
- 7. 2. INTEGRITY • The second goal of Network Security is "Integrity". Integrity aims at maintaining and assuring the accuracy and consistency of data. • The function of Integrity is to make sure that the data is accurate and reliable and is not changed by unauthorized persons or hackers. • The data received by the recipient must be exactly same as the data sent from the sender, without change in even single bit of data. • cryptography plays a very major role in ensuring data integrity.
- 8. 3. AVAILABILITY Availability: The third goal of network security is "Availability". Availability of information refers to ensuring that authorized parties are able to access the information when needed. Information only has value if the right people can access it at the right times. Denying access to information has become a very common attack nowadays. How does one ensure data availability? Backup is key. Regularly doing off-site backups can limit the damage caused by damage to hard drives or natural disasters.
- 9. Levels of Impact We can define 3 levels of impact from a security breach Low Moderate High
- 10. Low Impact • The loss could be expected to have a limited adverse effect on organizational operations, organizational assets, or individuals. • The loss of confidentiality, integrity, or availability might – (i) minor damage to organizational assets; – (ii) minor financial loss; or – (iii) minor harm to individuals.
- 11. Moderate Impact • The loss could be expected to have a serious adverse effect on organizational operations, organizational assets, or individuals. • A serious adverse effect means that, for example, the loss might – (i) the functions is significantly reduced; – (ii) result in significant damage to organizational assets; – (iii) result in significant financial loss; or – (iv) result in significant harm to individuals that does not involve loss of life or serious, life-threatening injuries.
- 12. High Impact • The loss could be expected to have a severe or catastrophic adverse effect on organizational operations, organizational assets, or individuals. • A severe or catastrophic adverse effect means that, for example, the loss might – (i) cause a severe degradation – (ii) result in major damage to organizational assets; – (iii) result in major financial loss; or – (iv) result in severe or catastrophic harm to individuals involving loss of life or serious life threatening injuries.
- 13. Challenges of Computer Security 1. Computer security is not simple 2. One must consider potential (unexpected) attacks 3. Procedures used are often counter-intuitive 4. Must decide where to deploy mechanisms 5. Involve algorithms and secret info (keys) 6. A battle of wits between attacker / admin 7. It is not perceived on benefit until fails 8. Requires constant monitoring 9. Too often an after-thought (not integral) 10. Regarded as impediment to using system
- 14. Aspects of Security The 3 aspects of information security: – Security Attack – Security Mechanism – Security Service • Security attack: Any action that compromises the security of information owned by an organization. • • Security mechanism: A process (or a device) that is designed to detect, prevent, or recover from a security attack. • • Security service: A processing or communication service that enhances the security of the data processing systems and the information transfers of an organization.
- 15. • Attack - An assault on system security that derives from an intelligent threat; that is, an intelligent act that is a deliberate attempt (especially in the sense of a method or technique) to evade security services and violate the security policy of a system. There are two types of attacks. • 1. Passive Attack 2. Active Attack
- 16. Handling Attacks • Passive attacks – A passive attack attempts to learn or make use of information from the system but does not affect system resources. • Passive attacks are in the nature of eavesdropping on, or monitoring of, transmissions. • These attacks are difficult to detect because they do not involve any alteration of the data.
- 17. Passive Attack - Interception release of message contents
- 18. Passive Attack: Traffic Analysis Observe traffic pattern Traffic analysis - monitor traffic flow to determine location and identity of communicating hosts and could observe the frequency and length of messages being exchanged
- 19. Active Attack Active attacks involve some modification of the data stream or the creation of a false stream It can be subdivided into four categories: masquerade, replay, modification of messages, and denial of service: • Masquerade of one entity as some other • Replay previous messages • Modify/alter (part of) messages in transit to produce an unauthorized effect • Denial of service - prevents or inhibits the normal use or management of communications facilities
- 20. Active Attack: Interruption Block delivery of message
- 21. Active Attack: Fabrication Fabricate message
- 23. Active Attack: Modification Modify message
- 24. Model for Network Security This general model shows that there are four basic tasks in designing a particular security service. 1. Design a suitable algorithm for the security transformation 2. Generate the secret information (keys) used by the algorithm 3. Develop methods to distribute and share the secret information 4. Specify a protocol enabling the principles to use the transformation and secret information for a security service
- 25. Model for Network Access Security using this model requires us to: 1. select appropriate gatekeeper functions to identify users 2. implement security controls to ensure only authorised users access designated information or resources