Security services and mechanisms

This presentation describes about security goals, security services, security mechanisms and techniques

1. CRYPTOGRAPHY AND NETWORK SECURITY S.Rajapriya , Assistant Professor of IT

2. Security Services The International Telecommunication Union – Telecommunication Standardization Sector provides some security services and mechanisms to implement the security services . There are 5 services related to the security goals and attacks.

3. Data Confidentiality : It is designed to protect data from disclosure attack. The service defined by X.800 is very broad an encompasses confidentiality of the whole message. It is designed to prevent snooping an traffic analysis attack. Data Integrity : It is designed to protect data from modification, insertion, deletion and replaying by an adversary.

4. Authentication : This service provides authentication to the party on the other of the line. If it is a connection oriented communication, it provides authentication during the connection establishment. For connectionless communication, it authenticates the source of the data. Nonrepudiation : This service protects against repudiation by either the sender or receiver of the data. The receiver – with the proof of origin, prove the identity of the sender if denied. The sender – with the proof of delivery, prove the data was delivered

5. Access Control : This service provides protection against unauthorized access to data which involves reading, writing, modifying executing the programs etc.,

6. Security Mechanisms ITU-T (X.800) defined some mechanisms to provide security services.

7. Encipherment : Hiding or covering the data. Two techniques : Cryptography and Steganography Data Integrity : This mechanism appends to the data a check value created by a specific process from the data itself. The receiver receives the data and the check value – creates a new check value from the received data and compares with the received one. If they are same then the integrity of the data is preserved.

8. Digital Signature : It is a means by which the sender can electronically sign the data and the receiver can electronically verify the data. Authentication Exchange : Two entities exchange some messages to prove their identity to each other. Traffic Padding: It means inserting some bogus data into the data traffic to thwart the adversary’s attempt to use the traffic analysis.

9. Routing Control: It means selecting and changing different available routes between the sender and the receiver. Notarization : Notarization means selecting a trusted third party to control the communication between the two entities. Access Control: It uses methods to prove that a user has access rights to the data. Example : Passwords, PINs

10. Relationship between services and mechanisms

11. Techniques Cryptography : Cryptography is an important aspect when we deal with network security. ‘Crypto’ means secret or hidden. Cryptography is the science of secret writing with the intention of keeping the data secret.  Cryptography is classified into symmetric cryptography, asymmetric cryptography and hashing.

12. Symmetric-key encipherment : It involves usage of one secret key along with encryption and decryption algorithms which help in securing the contents of the message. The strength of symmetric key cryptography depends upon the number of key bits. It is relatively faster than asymmetric key cryptography. There arises a key distribution problem as the key has to be transferred from the sender to receiver through a secure channel.

13. Asymmetric-key encipherment : It is also known as public key cryptography because it involves usage of a public key along with secret key. It solves the problem of key distribution as both parties uses different keys for encryption/decryption. It is not feasible to use for decrypting bulk messages as it is very slow compared to symmetric key cryptography.

14. Hashing: It involves taking the plain-text and converting it to a hash value of fixed size by a hash function. This process ensures integrity of the message as the hash value on both, sender\’s and receiver\’s side should match if the message is unaltered.

15. Steganography : The word  Steganography  is derived from two Greek words- ‘ stegos ’ meaning ‘to cover’ and ‘ grayfia ’, meaning ‘writing’, thus translating to ‘covered writing’, or ‘hidden writing’.  Steganography  is a method of hiding secret data, by embedding it into an audio, video, image, or text file. It is one of the methods employed to protect secret or sensitive data from malicious attacks.  Cryptography makes the data unreadable, or hides the  meaning  of the data, while steganography hides the  existence  of the data. 

16. Historical use: In china, war messages were written on silk cloth and rolled into a small ball and swallowed by the messenger. In Rome and Greece, messages were carved on pieces of wood and dipped into wax to cover the writing. Invisible inks were also used. Null cipers were used to hide a secret message inside a message. Secret messages were photographed and reduced to a size of a dot.

17. Modern use: Today, any form of data can be digitized. Possible to insert secret binary information into the data during digitization process. It can also be used to protect copyright, prevent tampering. Text Cover: The cover of secret data can be text. We can use a single space for binary 0,two space for binary 1.

18. Image Cover: The cover of secret data can be under a color image. Other Cover: The cover of secret data can be covered under audio, video. It can also be compressed.

19. THANKYOU