1

P.S.R.ENGINEERING COLLEGE

SIVAKASI – 626 140.

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING

TWO MARK QUESTIONS AND ANSWERS

SUBJECT NAME : INFORMATION SECURITY

SUBJECT CODE : CS9224

CLASS / SEM : ME / I YEAR CSE / II

Prepared by Approved by

K.SELVAMURUGAN AP/CSE HOD / CSE

2 INFORMATION SECURITY (CS9224)

TWO MARK QUESTIONS AND ANSWERS UNIT: I

1. Define information Security? It is a well-informed sense of assurance that the information risks and controls are in balance. 2. What is Security? Security is “the quality or state of being secure-to be free from danger”. 3. What are the basic components of computer Security?

a. Confidentiality - Keeping data and resources hidden b. Integrity - Data integrity (integrity)

- Origin integrity (authentication) c. Availability - Enabling access to data and resources

4. What is confidentiality? Confidentiality is the concealment of information or resources. The need for keeping information secret arises from the use of computers in sensitive fields such as government and industry. For example. Military and civilian institutions in the government often restrict access to information to those who need that information. 5. What is Integrity? àIntegrity refers to the trustworthiness of data or resources, and it is usually phrased in terms of preventing or unauthorized change. àIntegrity includes data integrity (the content of the information) and origin integrity (the Source of the data, often called Authentication). For example A newspaper – The information is printed as received (preserving data integrity) But its source is incorrect (corrupting origin integrity). 6. What is Availability? Availability refers to the ability to use the information or resource desired. Availability is an Important aspect of reliability as well as of system design because an unavailable system is at all. For example. Bank’s secondary system server 7. What is a threat? A threat is a potential violation of security. The violation need not actually occur for there to be a threat. 8. What is an attack? The fact that the violation might occur means that those actions that could cause it to occur must be guarded against. Those actions are called attacks. 9. What are the different broad classes of threats?

1. Disclosure - Snooping 2. Deception - Modification, spoofing, repudiation of origin, denial of receipt 3. Disruption - Modification

4. Usurpation - Modification, spoofing, delay, denial of service

3 10. What do mean by snooping? Snooping, the unauthorized interception of information is a form of disclosure. It is a technique used to gain unauthorized access to computers. It is passive, suggesting simply that some entity is listening to communications. 11. Distinguish between policy and mechanism Policy: It is a statement of what is, and what is not allowed Mechanism: It is a method, tool or procedure for enforcing a security policy. 12. What are the goals of security? 1. Prevention: It means that an attack will fail 2. Detection: It is most useful when an attack cannot be prevented, but it can also indicate the effectiveness of preventative measures. 3. Recovery: To stop an attack and to assess and repair any damage caused by that attack, the system continuous to function correctly while an attack is underway. 13. Define Assurance System specification, design, and implementation can provide a basis for determining “how much” to trust a system. This aspect of trust is called assurance. 14. What are the operational issues?

1. Cost-Benefit Analysis 2. Risk Analysis 3. Laws and customs

15. What is cost-benefit analysis? If the data or resource is cost less, or are of less value, then their protection, adding security mechanisms and procedures is not cost effective, because the data or resources can be reconstructed more cheaply than the protection themselves. 16. What are the human issues? 1. Organizational Problems 2. People Problems 17. What is protection state? The state of the system is the collection of the current values of all memory locations, all secondary storage and all registers and other components of the system. The subset of this collection that deals with protection is the protection state of the system. 18. What is an access control matrix model? The simplest framework for describing a protection system is the access control matrix model, which describes the rights of users over files in a matrix. 19. What is copyright with an example? The copyright allows the possessor to grant rights to another. This right is often considering a flag attached to other rights, it is known as copy flag. Eg: In Windows NT, the copy flag corresponds to the “P” (change permission) right. 20. What is own right with an example? The own right is a special right that enables possessors to add or delete privileges for themselves. It also allows the possessors to grant rights to others, although to whom they can be granted may be systems or implementation dependent. 21. What is security policy? Security policy is a statement that partitions the states of the system into a set of authorized ,or secure, states and a set of unauthorized, or non secure, states.

4 22. What is secure system? Secure system is a system that starts in an authorized state and cannot enter an unauthorized state. 23. What are the types of security policies? 1. Military security policy 2. Commercial security policy 3. Transaction oriented integrity security policy 4. Confidentiality security policy 5. Integrity policy 24. What are the types of access control? 1. Identity based access control 2. Mandatory access control 3. Originator controlled access control 25. What is an identity based access control? If an individual user can set an access control mechanism to allow or deny access to an object, that mechanism is a discretionary access control also called an identity based access control. 26. What is a mandatory access control? When a system mechanism controls access to an object and an individual user can not alter that access, the control is a mandatory access control, occasionally called as rule-based access control. 27. What is ORCON or ORGCON? An Originator controlled access control (ORCON or ORGCON) bases access on the creator of an object. 28. What is policy language? What are the different types of policy languages? A policy language is a language for representing a security policy. Types:

1. High-level policy languages 2. Low level policy languages

29. What is a high – level policy language? A policy is independent of the mechanisms. It describes constraints placed on entities and actions in a system. A high-level policy language is an unambiguous expression of policy. Such precision requires a mathematical or programmatic formulation of policy. 30. What is a low-level policy language? A low –level policy language is simply a set of inputs or arguments to commands that set, or check, constraints on a system. For example The UNIX-based windowing system X11 provides a language for controlling access to the console. 31. What are the examples of Academic computer security? 1. General University Policy 2. Electronic Mail policy 32. Explain in terms of security and precision? Definition of the Security and precision in terms of states of systems. It can devise a generic procedure for developing a mechanism that is both secure and precise. 33. What is a confidentiality policy? A Confidentiality policy, also called an information flow policy, prevents the unauthorized disclosure of information. Unauthorized alteration of information is secondary. For example

5 The navy must keep confidential the date on which a troop ship will sail. If the date is changed, the redundancy in the system and paperwork should catch that change. But if the enemy knows the date of sailing, the ship could be sunk. Because of extensive redundancy in military communications channels, availability is also less of a problem. 34. What is Bell-LaPadula Model? The Bell-LaPadula Model corresponds to military style classifications. It has influenced the development of many other models and indeed much of the development of computer security technologies. 35. What is tranquility? The principle of tranquility states that subjects may not change their security levels once they have been instantiated. 36. What are the types of tranquility? 1. Strong tranquility: The security levels do not change during the life time of the system. 2. Weak tranquility: The security levels do not change in a way that violates the rules of a given security policy. 37. What is an integrity policy? Integrity policies focus on integrity rather than confidentiality, because most commercial and industrial firms are more concerned with accuracy than disclosure. 38. What are the goals of integrity policies? 1. Users will not write their own programs, but will use existing production programs and databases. 2. Programmers will develop and test programs on a non production system: 3. A special process must be followed to install a program from the development system onto the production system. 4. The special process in requirement 3 must be controlled and audited. 5. The managers and auditors must have access to both the system state and the system logs those are generated. 39. What is Biba Integrity Model? Biba studied the nature of the integrity of systems. He proposed three policies, one of which was the mathematical dual of the Bell-LaPadula Model. 40. What is Ring policy? The ring policy ignores the issue of indirect and focuses on direct modification only. This solves the problems described above. The rules are as follows.

1. Any subject may read any object, regardless of integrity levels. 2. If s € S can reads o € O, then i(s)=min(i(s),i(o)),where i `(s) is the subject’s integrity level after the read. 3. s1 € S can execute s2 € S if and only if i(s2) ≤ i(s1).

41. What is Biba’s Model or Strict integrity policy? This model is the dual of the Bell-LaPadulla model, and is most commonly called “Biba’s model.” Its rules are as follows.

1. s € S can read o € O if and only if i(o). 2. s € S can write to o € O if and only if i(o) ≤ i(s). 3. s1 € S can execute s2 € S if and only if i(s2) ≤ i(s1).

42. What is Lipner’s integrity Matrix Model? Lipners returned to the Bell-LaPadula Model and combined it with the Biba model to create a model that conformed more accurately to the requirements of a commercial policy.

6 43. What is Clark-Wilson Integrity model? David Clark and David Wilson developed an integrity model radically different from previous models. This model uses transactions as the basic operation, which models many commercial systems realistically than precious models. 44. What are Lipner’s uses of the Bell-LaPadula Model? Lipner provides two security levels, in the following order à Audit Manager (AM): system audit and management functions are at this level. à System Low (SL): any process can read information at this level. 45. What is Lipner’s defined the five categories? àDevelopment (D): Production programs under development and testing but not yet in Production àProduction Code (PC): Production processes and programs àProduction Data (PD): data covered by the integrity policy àSystem Development (SD): system programs under development, but not yet in production use àSoftware Tools (T): programs provided on the production system not related to the sensitive or protected data 46. What is Chinese wall model? à The Chinese wall model is a model of a security policy that refers equally to confidentiality and integrity. àIt describes policies that involve a conflict of interest in business, and is as important to those situations as the Bell-LaPadula Model is to the military. For example British law requires the use of a policy similar to this, and correct implementation of portions of the model provides a defense in cases involving certain criminal charges. 47. What is a patient? A patient is the subject of medical records, or an agent for that person who can give consent for the person to be treated. 48. What is personal health information? Personal health information is information about a patient‘s health or treatment enabling that patient to be identified. 49. What is originator controlled access control? With an example. Graubert developed a policy called ORGCON (for” Originator CONtrolled”) in which a subject can give another subject rights to an object only with the approval of the creator of that object. For example The secretary of Defense of the United States drafts a proposed policy document and distributes it to her aides for comment. The aids are not allowed to distribute the document any further with out permission from the secretary .The secretary control dissemination; hence, the policy is ORCON. The trust in this policy is that the aides will not release the document illicitly- that is, without the permission of the secretary. 50. What is Role – based access control? With an example. The ability, or need, to access information may depend on one’s job functions. For example Allison is the bookkeeper for the Department of Mathematics. She is responsible for balancing the books and keeping track of all accounting for that department. She has access to all departmental accounts. She moves to the university’s office of Admission to become the head accountant (with a substantial raise). Because she is no longer the bookkeeper for the Department of Mathematics, she no longer has access to those accounts. When that department hires sally as its new bookkeeper, she will acquire full access to all those accounts. Access to the accounts is a function of the job of bookkeeper, and is not tied to any particular individual.

7 UNIT: II

1. What is Cryptography? Cryptography means Secret writing. Definition: A cryptosystem is a 5 tuple (E, D, M, K, and C) M-> set of plain text. C-> set of Enciphering functions. K->set of Keys. D : C*k -> M set of deciphering functions.

2. What is Classical Crypto system? • Also Called single key/ symmetric key • Is a Cryptosystem that use the same key for Decipherment Decipherment. • In this system Ek Є C and k Є K . • two types of classical cipher

i) Transposition cipher ii) Substitution cipher

3. Explain Substitution cipher with example?

è It changes character in the plain text to produce the cipher text. è Is susceptible to a statistical cipher text only attack. Example: The Caesar cipher had a key 3 means, altering each letter in the plain text by mapping it into the letter 3 characters later in the alphabet.

4. Explain Transposition cipher with example? è It rearranges the character in the plaintext to form the cipher text. è The Letters are not changed.

Example: The rail fence cipher is composed by writing the plaintext in 2 rows, proceeding down, then across, and reading the cipher text across, then down. HLOOL ELWRD result of cipher text HLOOLELWRD Result: HE LL OW OR LD

5. Define VIGENERE cipher with example? It chooses a sequence of keys, represented by a string. The key letters are applied to successive plaintext characters, when the end of the key is reached, the key starts over. è The length of the key called PERIODS of the cipher.

Example: The 1st line of the limerick is enciphered using the key “BENCH” as follows: Key B ENCHBENC HBENC HBENCH BENCHBENCH Plain text A LIMERICK PACKS LAUGHs ANATOMICAL Cipher text B PVOLSMPM WBGXU SBYTJZ BRNVVNMPCS Weakness: The primary weakness of the Vigenère cipher is the repeating nature of its key.

6. What is onetime pad? Is a variant of the Vigenere cipher? The key string is chosen at random and is at least as long as message so it does not repeat. è Technically it is a threshold scheme and is provably impossible to break

8 ISSUES: The implementation issues of the pad including random generation of the key and key distribution.

7. What is Data Encryption Standard (DES)? -> It was designed to encipher sensitive but Non classified data. It is Bit Oriented. -> Also called as Product cipher (use both Transposition and Substitution). -> Input, Output, Key is each 64 bit Long. The set of 64 bit called BLOCK. -> Cipher consists of 16 rounds. -> Each round uses a separate key of 48 bits. -> These rounds are generated from the key block by dropping the PARITY BITS (reducing key size to 48 bits), permuting the bits, and extracting 48 bits.

8. Why not always use a onetime pad?

è One of two possibilities:

a. A new key is exchanged each time a message is sent, but then how is key exchange made secure?

b. A very long key is kept by both sender and receiver (a code book), but code books can be captured.

è Some version of option 2 is viable for some circumstances.

9. What is the weakness of 1 time pad? None in theory. Two in practice. Ø Key not truly random: For example, if it is known that the key is a piece of English text,

guessing space is reduced. Brute force reopened as a possibility. Ø Plain text not random. Known or guessable plain text. But note: Even if the possibilities are

reduced to one of two messages of equal length, unless the key is nonrandom, there is no way of choosing between them.

10. Explain in terms of private key give example? Ø In cryptography, a private or secret key is an encryption/decryption key known only to the party

or parties that exchange secret messages. Ø In traditional secret key cryptography, a key would be shared by the communicators so that

each could encrypt and decrypt messages. Ø The risk in this system is that if either party loses the key or it is stolen, the system is broken. A

more recent alternative is to use a combination of public and private keys. In this system, a public key is used together with a private key.

11. Explain in terms of public key?

Ø In cryptography, a public key is a value provided by some designated authority as an encryption key that, combined with a private key derived from the public key, can be used to effectively encrypt messages and digital signatures.

Ø The use of combined public and private keys is known as asymmetric cryptography. A system for using public keys is called a public key infrastructure (PKI).

12. What are the 3 condition for public key cryptography?

Ø It must be computationally easy to encipher/ decipher a message given the appropriate key. Ø It must be computationally infeasible to derive the private key from the public key. Ø It must be computationally infeasible to determine the private key from a chosen plaintext

attack.

9 • 1st ciphers meet the above then generate a shared session key. • 2nd provides secrecy and authentication.

13. Define Diffe Hellman with example?

It was the 1st public key crypto system.Both sender and receiver use ithis same alg t generate a common key. It is based on descrete logarithmic problem.

Ø To find a value of key use n=gk mod p for a given n,g,p. Ø In this crupto system all users share a common modulous p &g other than 0,1/p-1.

Example:

P=53, g=70 , kalice=5, kbob=7.

To find public key: K alice=175mod53 = 40 , K bob=177mod53 = 6

To find secret key: S bob, alice=KalicekBobmod p = 407 mod53 = 38

S alice ,bob=KBobkAlicemod p = 65 mod53 = 38

Ø Diffie Hellman is an example of Symmetric key exchange protocol.

14. Define the term of RSA?

Ø RSA is an Internet encryption and authentication system that uses an algorithm developed by Ron Rivest, Adi Shamir, and Leonard Adleman.

Ø The RSA algorithm is the most commonly used encryption and authentication algorithm. Ø The encryption system is owned by RSA Security. The company licenses the algorithm

technologies and also sells development kits Ø Is a type of Exponentiation cipher?

Formula:

i) To evaluate encrypted msg : c= me mod n where m=message ii) To evaluate original msg : m=c d mod n

15. What is a cryptography checksum function?

Ø It is also called Strong Hash function or a strong 1 way function. Ø h : A -> B is a function that has following properties;

i) For any x Є A , h(x) is easy to compute. ii) For any y Є B , it is computationally infeasible to find x ЄA such that h(x)=y. iii) It is computation all infeasible to find x,x’ ЄA such that x ≠ x’ and h(x)=h(x’) (such a pair

is called collision). iv) Given any xЄA it is computationally infeasible to find another x’ ЄA such that x≠ x’ and

h(x')=h(x).

16. What is pigeon hole principle?

It states if there are n containers for n+ 1 object, at least 1 container will hole 2 objects.

Example: consider a cryptographic check sum function that hashes of 3 bits and a set of files each of which contains 5 bits.

10 23=8 possible hashes for 25 = 32 files.

Hence an atleast 4 different file corresponds to the same hash.

17. Difference b/w Cryptography and stegnography?

Cryptography Stegnography • Cryptography is the study of hiding

information. In Steganography, only the sender and the receiver know the existence of the message

• In cryptography the existence of the encrypted message is visible to the world.

• Cryptographic methods try to protect the content of a message.

• By combining Steganography and Cryptography one can achieve better security.

• Steganography deals with composing hidden messages so that only the sender and the receiver know that the message even exists.

• In Steganography, only the sender and the receiver know the existence of the message

• Steganography removes the unwanted attention coming to the hidden message.

• Steganography uses methods that would hide both the message as well as the content.

18. Explain the term of HMAC?

è Is a generic term for algorithm that uses a key less hash function and cryptographic key to produce a keyed hash function?

è The need for HMAC arose because keyed hash funs are derived from cryptographic function. è HMAC builds on a keyless hash function using a cryptographic key to create a keyed hah

function.

19. What are the goals of Key exchange?

i) Enable the communication to takes place secret key using a shared cryptographic key. ii) Solution: To this problem must meet following criteria

è The key that Alice and bob are to share cannot be transmitted in the clear either it must be in enciphered form or key must not be derived by 3rd party.

è Decide to trust 3rd party. è The crypt system and protocols are publicly known.

20. Difference between a session key and an interchange key?

Session key Interchange key • A session key is a cryptographic

key associated with the communication itself.

• It prevents forward search. • A forward search attack when the

set of plain text message is small.

• An interchange key is a cryptographic key associated with a principal to a communication. the message even exists.

• Limits the amount of data encipher by a single key and reduces the

11 • The advertisory enciphers all plain text using the target’s public key.

• A randomly generated session key would prevent the above attack.

likelihood of Eavesdropper being able to break the cipher.

• It hinders the effectiveness of reply attacks

21. What is classical cryptographic key exchange?

è Sharing of common key b/w sender and receiver before communication has takes place. è How to share a common key as follows

i) Alice->cache:{request for session key to BOB}Kalice ii) cache ->Alice:{ksession}kalice{ksession}kbob. iii) Alice->Bob{ksession}kbob.

22. Explain the terms of Kerberos?

Kerberos is designed to enable two parties to exchange private information across an otherwise open network. It works by assigning a unique key, called a ticket, to each user that logs on to the network. The ticket is then embedded in messages to identify the sender of the message.

23. What is key generation?

è A sequence of cryptographically random numbers is a sequence of numbers n1, n2….. Such that for any positive integers an observer cannot predict nk.Even if n1,…nk-1 are known.

è A random number generator requires a physical source of randomness such as background radiation or some other quantifiable physical phenomenon.

24. What is cryptographic key infrastructure?

è TO bind an identity to a key. è Creating a message containing a representation of identity, the corresponding public key and a

timestamp and having a tested authority sign it. è Calice={ealice|| alice || T}dCathy è This type of structure is called a certificate. A certificate is a token that binds an identity to a

cryptographic key.

25. What is X.509 certificate signature chains?

è It defines a certificate formats and certification validation in a generic context è The components of x.509 certificate are i) version ii) serial no iii) signature alg identifier, iv)

Issuers distinguished name v) validity interrupt vi) subjects distinguished name vii) issuers unique identifier viii) sub public key information ix) Extension x) signature

26. What is Digital signature?

è A Ds is construct that authenticates both the orgin and the contents of a message that is provable to a dis interested 3rd party.

è A DS provides a service of non repudiation. è A digital signature is an electronic equivalent of an individual's signature. It authenticates the

message to which it is attached and validates the authenticity of the sender. In addition, it also

12 provides confirmation that the contents of the message to which it is attached, have not been tampered with, en route from the sender to the receiver.

27. What are the algorithms in Digital signature?

3 Algorithm

• A key generation algorithm that selects a private key uniformly at random from a set of possible private keys. The algorithm outputs the private key and a corresponding public key.

• A signing algorithm that, given a message and a private key, produces a signature. • signature verifying algorithm that, given a message, public key and a signature, either accepts

or rejects the message's claim to authenticity

UNIT: III 1. What are design principles? Specific design principles underline the design and implementation mechanism for supporting security policies. The principles build on ideas of the simplicity and restriction. 2. What is identity? Simply computer’s representation of an entity. Principal is a unique identity. An identity specifies the principal. 3. What are file and object?

13 • Identity of a file or other entity depends on system containing object.

• If the object resides on a different system, the name must encode the location of the objects.

4. Explain in terms of user. • Exact representation tied to system

• Example: UNIX systems

Login name: used to log in to system. Logging usually uses this name User identification number (UID): unique integer assigned to user, Kernel uses UID to identify users. 5. Explain in terms of Groups and Roles. Groups:

• Used to share access privileges

• First model: alias for set of principals

Ø Processes assigned to groups Ø Processes stay in those groups for their lifetime

• Second model: principals can change groups

Ø Rights due to old group discarded; rights due to new group added. Role:

• Group with membership tied to function

Ø Rights given are consistent with rights needed to perform function • Uses second model of groups

• Example: DG/UX

6. Short notes on Naming and Certificate. • Certificates issued to a principal

Ø Principal uniquely identified to avoid confusion • Problem: names may be ambiguous

Ø Does the name “Matt Bishop” refer to: • The author of this book?

7. What is an identity on the web? • Host identity

• State and Cookies

• Anonymity

Ø Anonymous email

Ø Anonymity: good or bad?

8. What are static and dynamic identifiers? Ø Static identifiers: do not change over time Ø Dynamic identifiers: changes as a result of an event or the passing of time

9. What is host identity? • Bound up to networking

Ø Not connected: pick any name Ø Connected: one or more names depending on interfaces, network structure, context

14 • Name identifies principal.

• Address identifies location of principal. May be virtual location (network segment) as opposed to physical location

10. What is Anonymity on the Web? • Recipients can determine origin of incoming packet ,Sometimes not desirable

• Anonymizer: a site that hides origins of connections

• Usually a proxy server

• Destination host sees only anonymizer

11. What do we need an access control Mechanism? Ø Its variation of Access control matrix. Ø Insert, update, delete function are difficult in access control matrix, so we go for Access control

Mechanism. Ø ACL entries can add rights, but on deny, access is denied.

12. What are state and cookies? • Cookie: Token containing information about state of transaction on network

• Some of the fields in cookies:

(i) name, value (ii) expires (iii) domain (iv) secure

13. Which subjects can modify an object ACL? Ø Creator is given own right that allows this Ø System R provides a grant modifier (like a copy flag) allowing a right to be transferred, so

ownership not needed • Transferring right to another modifies ACL

14. Do the ACL apply to a privileged user? Ø Solaris: abbreviated lists do not, but full-blown ACL entries do Ø Other vendors: varies

15. Do the ACL support Groups and wildcard? • Classic form: no; in practice, usually AIX: base perms gave group sys read only

Permit -w- u:heidi, g=sys Line adds write permission for heidi when in that group

Ø UNICOS: • holly : gleep : r

• holly : * : r

• * : gleep : r

16. Define Conflicts? Deny access if any entry would deny access

Ø AIX: if any entry denies access, regardless or rights given so far, access is denied Ø Apply first entry matching subject , Cisco routers: run packet through access control rules (ACL

entries) in order; on a match, stop, and forward the packet; if no matches, deny.

17. Explain in terms of Revocation of Rights? Revocation or the prevention of a subject accessing an object requires that data subjects rights to be deleted from the objects ACL.

15 18. What is capability?

• Rows of access control matrix

• Each subjects is associated with it set of pairs. Each pair contains an objects and set of rights.

• It encapsulates the object identity.

19. What is the Mechanism used to protect capability? • Tagged architecture, Bits protect individual words

• Paging/segmentation protections

• Like tags, but put capabilities in a read-only segment or page

• Cryptography.

20. What is copying and amplifying capabilities? • Allows temporary increase of privileges

• Needed for modular programming

• A copy flag is associated with capabilities.

21. What is lock and key? • Associate information (lock) with object, information (key) with subject

Ø Latter controls what the subject can access and how Ø Subject presents key; if it corresponds to any of the locks on the object, access granted

• This can be dynamic.

22. What is type checking? Type checking restricts access on the basis of the types of the subject and object .it is a form of locks and keys access control, the pieces of information being the type system use type checking in areas other then security. 23. What is ring based Access control?

• Process (segment) accesses another segment

• Read

• Execute

• Gate is an entry point for calling segment

• Rights:

• r read,w write

• a append, e execute

24. What is PACLs? • Propagated Access Control List, Implements ORGON

• Creator kept with PACL, copies, Only owner can change PACL

Ø Subject reads object: object’s PACL associated with subject Ø Subject writes object: subject’s PACL associated with object

Notation: PACLs means s created object.

16 25. What are the examples for Information flow?

• Command is x := y + z; where:

– 0 ≤ y ≤ 7, equal probability

– z = 1 with prob. 1/2, z = 2 or 3 with prob. 1/4 each

• s state before command executed; t, after; so

– H(ys) = H(yt) = –8(1/8) lg (1/8) = 3

– H(zs) = H(zt) = –(1/2) lg (1/2) –2(1/4) lg (1/4) = 1.5

• If you know xt, ys can have at most 3 values, so H(ys | xt) = –3(1/3) lg (1/3) = lg 3

26. What is complier Base Mechanism? • Detect unauthorized information flows in a program during compilation

• Analysis not precise, but secure

Ø If a flow could violate policy (but may not), it is unauthorized, Ø No unauthorized path along which information could flow remains undetected • Set of statements certified with respect to information flow policy if flows in set of statements do

not violate that policy

27. What is Execution based Mechanism? • Detect and stop flows of information that violate policy

Ø Done at run time, not compile time • Obvious approach: check explicit flows, Problem: assume for security, x ≤ y

If x = 1 then y: = a; When x ≠ 1, x = High, y = Low, a = Low, appears okay—but implicit flow violates condition! 28. What are variable classes?

• Up to now, classes fixed and Check relationships on assignment, etc.

• Consider variable classes ,Fenton’s Data Mark Machine does this for PC and On assignment of form y := f(x1, …, xn), y changed to lub{ x1, …, xn }

29. What all are the impact of confinement problem? • Server balances bank accounts for clients

• Server security issues: (1)Record correctly who used it,(2)Send only balancing info to client

• Client security issues: (i)Log use correctly (ii)Do not save or retransmit data client sends

30. What is virtual machine?

• Program that simulates hardware of a machine .Machine may be an existing, physical one or an abstract one

• Existing OSes do not need to be modified

• Run under VMM, which enforces security policy

17 • Effectively, VMM is a security kernel.

31. What is isolation?

• Present process with environment that appears to be a computer running only those processes being isolated .Process cannot access underlying computer system

• Run process in environment that analyzes actions to determine if they leak information

UNIT: IV 1. What is malicious logic?

2. What is a Trojan horse?

3. What is computer virus?

4. What are Boot sector infectors?

18 5. What is an executable infector?

6. What is a multipartite virus?

7. What is a TSR virus?

8. What is a Stealth virus?

9. What is an Encrypted virus?

10. What is a polymorphic virus?

11. What is a macro virus?

12. What are Computer worms? with an example?

13. Explain in the term logic bonds?

14. What is a bacterium or rabbit?

15. What is an information flow metrics with an example?

16. Explain in term reducing the Rights.

17. Explain in term Sandboxing?

18. What is a TSR virus?

19. Explain in term reducing the Rights

20. Explain in term Sandboxing

21. What is flow hypothesis methodology?

22. What are the types of flow hypothesis methodology?

23. What is an information Gathenis and flow hypothesis?

24. What is flaw testing?

25. What is flaw Generalization?

26. What is flaw Elimination?

27. What is the classification of vulnerability?

28. What is an auditing system?

29. What are the components of anatomy of an auditing system?

30. What is Analyzers?

31. Explain in term log sanitization?

32. What is state – based auditing

33. What is transition – Based Auditing?

34. What is an Auditing mechanism?

35. What is an Audit browsing?

36. What are the principles of intrusion detection?

37. What is an Anomaly modeling?

38. What is misuse modeling?

39. What are the six phases of intrusion handling?

Big Question:

19 1. Explain the intrusion detection mechanism that helps in safe guarding the data

2. Write short note an the following

1. Vulnerability analysis

2. Auditing

3. Explain the following

I. Information gathering and flaw hypothesis

II . Flaw Testing

III. Flaw Generalization

IV. Flaw Elimination

4. What is an auditing System? List and discus the issues involved in designing an auditing system.

5. Explain in detail about malicious logic?

UNIT V

1. What are the goals of the Drib’s security policy?

2. What is a Data class?

3. What are the classifications of data classes?

4. What is user’s class?

20 5. What are the mechanisms provided for user classes?

6. What are the transformation rules for user classes?

7. Explain in the of consistency check?

8. What is mean by DMZ?

9. What is firewall?

10. What is proxy?

11. What is principle of fail-safe defaults?

12. What is principle of least privilege?

13. What are the steps of DMZ mail server?

14. What is host identity?

15. What is DMZ DNS server?

16. What is user security?

17. What are trusted hosts?

18. What is file deletion?

19. What are writable devices?

20. What are the writable devices?

21. What is a smart terminal?

22. Explain in terms sending unexpected content?

23. What is framework?

24. What is program security?

25. What are the access to roles and commands?

26. What is the access control record?

27. What are the devices in user security?

28. List the function performed by a firewall

29. Differentiate system security and network security

30. Why it is essential to prevent our network from hackers?

Big Question:

1. Explain the following:

(i) User Security

(ii) Program Security

21

2. Explain the stepwise procedure adopted in securing a network?

3. Discuss how analysis of the network infrastructure can be done using firewalls.

4. Present a tutorial on system security.

5. Explain in detail about Network Organization?

6. Discuss about files and devices of User security.

7. Explain in detail about processes of user security.

8. Discuss about design of the program security.

9. Explain in detail about Refinement and implementation?

10. Discuss about common security – Related programming problems.

P.S.R.ENGINEERING COLLEGE

SIVAKASI – 626 140.

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING

TEST-I

22

SUB NAME: INFORMATION SECURITY TME: 9 .00 am – 10.45 am SUB CODE: CS9224 DATE: 09.03.2012 CLASS / SEM: ME / I YEAR CSE / II Marks: 50

PART – A 7 x 2 =14

1.What is a threat? What are the different types of broad classes?

2.What is denial of service?

3.State the principle of attenuation of privilege?

4.What are the advantages of Access control matrix?

5.Give the significance of confidentiality policies?

6.What is Clark – Wilson integrity model?

7.What is Originator access control?

PART – B 3 x 12 = 36 8. (i). Explain in details about an overview of computer security? (12)

(OR) ii).(a).With relevant examples discuss access control by Boolean expression evaluation? (6) (b).Discuss how access can be controlled using history? (6) 9. (i) What is Security policy? List and discuss the different types of security policies? Give relevant examples? (12)

(OR) (ii) Explain in detail about Bell – Lapadula model? (12) 10. (i) Explain the following: (a). Biba integrity model (6) (b). Lipner’s integrity model (6) (OR) (ii) Discuss in detail about Chinese access control? (12) _____________________________________________________________________

P.S.R.ENGINEERING COLLEGE SIVAKASI – 626 140.

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING

TEST-II

23

SUB NAME: INFORMATION SECURITY TME: 9 .00 am – 10.45 am SUB CODE: CS9224 DATE: 05.04.2012 CLASS / SEM: ME / I YEAR CSE / II Marks: 50

PART – A 7 x 2 =14

8.Differentiate cryptography and stegnography.

9.With an example explain substitution cipher?

10. Explain in terms: public key; private key, give example for each?

11. Distinguish between a session key and an interchange key?

12. What is the speciality of digital signature?

13. With an example explain transposition cipher?

14. What are the goals of key exchange?

PART – B 3 x 12 = 36 8. (a). Diagrammatically illustrate and discuss key generation for the Data Encryption Standard (12) (OR) (b). With an example explain the Rivest – Shamir Adleman (RSA) algorithm for digital Signatures (12) 9. (a). Explain how key management is carried out in the cryptography process. (12)

(OR) (b). Explain in detail about cryptographic key infrastructures. 10. (a). Explain in detail about storing and revoking keys (12) (OR) (b). Explain any two cipher techniques used for providing security in a network. (12) ____________________________________________________________________

P.S.R.ENGINEERING COLLEGE SIVAKASI – 626 140.

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING

TEST-III

24

SUB NAME: INFORMATION SECURITY TME: 9 .00 am – 10.45 am SUB CODE: CS9224 DATE: 03.05.2012 CLASS / SEM: ME / I YEAR CSE / II Marks: 50

PART – A 7 x 2 =14

15. What are cookies?

16. What is ring based access control?

17. What do we need an access control mechanism?

18. Give the impact of confinement Problem.

19. What are the examples of information flow controls?

20. What is identity?

21. What are the uses of covert channels?

PART – B 3 x 12 = 36 8. (a). Explain in detail about the Design Principles (OR) (b).What is an Access control list? Discuss how access control lists can be created and maintained. (12)

9. (a). Explain in detail about Nonlattice information flow polices. (12) (OR)

(b). (i) What are static and dynamic identifiers? (6) (ii) List and discuss the security issues with the domain name service. (6)

10. (a). Explain in detail about the Confinement Problem (12) (OR) (b). Explain the following (i) Compiler - Based Mechanisms (6) (ii) Execution -Based Mechanisms (6)

P.S.R.ENGINEERING COLLEGE

SIVAKASI – 626 140.

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING

MODEL EXAMINATION SUB NAME: INFORMATION SECURITY

25 TME: 9 .30 am – 12.30 am SUB CODE: CS9224 DATE: 16.05.2012 CLASS / SEM: ME / I YEAR CSE / II Marks: 100

PART – A 10 x 2 = 20

1. What is denial of service?

2. State the principle of attenuation of privilege?

3. With an example explain substitution cipher?

4. Explain in terms: public key; private key, give example for each?

5. What do we need an access control mechanism?

6. Give the impact of confinement Problem.

7. What is malicious logic?

8. Explain the term vulnerability analysis.

9. List the functions performed by a firewall?

10. What are trusted hosts?

PART – B 5 x 16 = 80 8. (a). (i). With relevant examples discuss access control by Boolean expression evaluation? (8) (ii). Discuss how access can be controlled using history? (8)

(OR) (b). What is Security policy? List and discuss the different types of security policies? give relevant examples? (16)

9. (a). Diagrammatically illustrate and discuss key generation for the Data Encryption Standard (16) (OR)

(b). Explain any two cipher techniques used for providing security in a network. (16)

10. (a). Explain in detail about the Access Control Mechanism that supports network security. (16) (OR)

(b). (i) What are static and dynamic identifiers? (8) (ii) List and discuss the security issues with the domain name service. (8) 11. (a). What is an auditing system? List and discuss the issues involved in designing an auditing system. (16) (OR) (b). Explain the Intrusion Defection Mechanism that helps in safe guarding the data. (16)

26 12. (a). Explain the following (i) User Security (8) (ii) Program Security (8) (OR) (b). Explain the stepwise procedure adopted in securing a Network. (16)

ALL THE BEST