Information Security policies

Question 1

What is cryptography?

Answer 1

Enabling technology that turns an insecure communication facility into a secure one by guarantees one or more of the following information security policies, confidentiality, integrity, availability, nonrepudiation, authentication, anonymity and unobservability

also the science of secret writing

Question 2

What is steganography?

Answer 2

the science of hiding messages inside other messages

Question 3

What is cryptanalysis?

Answer 3

science of recovering the plaintext from the ciphertext

Question 4

What are the CIA properties?

Answer 4

Confidentiality (Secrecy): No improper disclosure of information.
Integrity: No improper modification of information.
Availability: No improper impairment of functionality/service.

Confidentiality: No unauthorized access to information.
Integrity: No unauthorized modification of information.
Availability: No unauthorized impairment of functionality

Question 5

What is confidentiality?

Answer 5

information is not learnt by unauthorised principals
Attack against confidentiality - passive attack( listen or read )

Confidentiality is guaranteed when Charlie, who is not authorised to read the message Alice is sending to Bob, is not able to read the message

Confidentiality presumes a notion of authorized party, or more generally, a security policy saying who or what can access our data. The security policy is used for access control

Question 6

Example of confidentiality

Answer 6

Confidentiality can be achieved if you send a letter from A to B rather than an email (email is over the internet so everyone along the way can read it). To prevent this, encryption, access control and network security.

Email is not a letter but a postcard!

Question 7

What is privacy?

Answer 7

1. You choose what information you want other people to know
2. Confidentiality of information that you don’t want to share
   (confidentiality for individuals)

Question 8

What is anonymity?

Answer 8

1. a condition where your true identity is not known.
2. Confidentiality of your identity
3. Hiding your activity amongst other similar activities.
4. Charlie does not know the identity of the sender or the receiver.

Question 9

Privacy and anonymity on public networks

Answer 9

1. internet is designed on a public network
   - machines on your LAN can see your traffic
2. Routing info is public
   - a passive observer can see who is talking to who
   - IP packet header - shows source and destination
   - packet route can be tracked (traffic analysis)
3. Encryption
   - does not hide identities of sender and receiver
   - hides payload but not routing info

Question 10

What is an anonymity set?

Answer 10

a group in which your actions (sending, receiving, communication and relationships) cannot be distinguished from the actions of anyone else in the group - bigger the group, better

YOU CANNOT BE ANONYMOUS BY YOURSELF

Question 11

What are the attacks on anonymity?

Answer 11

1. Passive traffic analysis:
   - observing packet route to identify the sender and receiver
2. Active traffic analysis:
   - injecting packets or putting a timing signature on packet flow
3. Compromise of routers:
   - it is not obvious about what nodes have been compromised
   - assuming that some fraction of the nodes are good but not sure which ones (do not trust just one individual node only)

Question 12

What is unlinkability?

Answer 12

1. This is the unlinkability of action (sending the email) and identity (identity of the sender)
2. sender and his email are no more related after
   observing communication than they were before - once the sender sends the email, they are no longer related to each other.

Question 13

What is unobservability?

Answer 13

HARD TO ACHIEVE

an observer cannot tell if a certain action took place or not.

Question 14

What is integrity?

Answer 14

data has not been (maliciously) altered
Attack against integrity - active attack where Charlie modifies the message between Alice and Bob

Alice -> Charlie( modifies it) -> Bob
Integrity is guaranteed whenever Charlie, who is not authorised to alter the message, is not able to modify the message.

Question 15

What is availability?

Answer 15

data or services cannot be accessed by unauthorised principals
attack against availability - Charlie disrupts the communication between Alice and Bob (disrupts the service)

Question 16

Threats to availability

Answer 16

1. External environmental events
   - fire
   - pulling a server plug
2. Accidental or malicious attacks in software
   - infecting a system with a debilitating virus
3. DoS attacks or break-ins
   - prevent the Denial of Service attacks by using fire-walls, redundant hardware, backups, virus scanners…
   - difficult to cover all the threats and still have a usable system.

Question 17

What is accountability?

Answer 17

actions are recorded and therefore can traced to the responsible principals.
If Alice sends a message to Bob, then Bob can track who the message was from.

keeping a secure audit trail is important so that actions
affecting security can be traced back to the responsible party - however, the violation is that the audit trail can be modified or tampered.

Question 18

What is non-repudiation?

Answer 18

STRONGER FORM OF ACCOUNTABILITY
actions that have been done cannot be denied.

If Alice sends a message to Bob, then Alice cannot deny that she sent the message and Bob cannot deny that he received the message.

Question 19

What is authentication?

Answer 19

principals or data origin can be identified accurately.
data or services are only available to authorised identities.

attack against authentication: Masquerades - Charlie pretends to be Alice and communicates with Bob

Question 20

More on authentication - verification and methods

Answer 20

Authentication is verification of the identity of a person or a system (says that you are who you are claiming to be)

Methods for authentication are often characterised as:

1. something you have, e.g. an entry card,
2. something you know, e.g. a password or secret key, or
3. something you are, e.g. a fingerprint, signature, biometric.

Question 21

Security is a whole system issue

Answer 21

protect the software, hardware, physical environment, personnel, corporate and legal structures

Question 22

What are the security mechanisms/ countermeasures?

Answer 22

Need to consider how different mechanisms can be used to achieve goals in the face of threats, and what some of the challenges are.

Challenge: employing adequate mechanisms and demonstrating that the resulting system is secure BUT Designing adequate mechanisms is challenging and careful “screening” is not enough.

Question 23

What are the protection countermeasures?

Answer 23

1. Prevention - prevent security breaches by system design and employing appropriate security technologies as defences. For example, using a firewall to prevent external access to corporate
   intranets.

Prevention is the most important protection measure.

2. Detection - In the event of a security breach, we try to ensure that it will be detected. Logging and MACs (file hashes to detect alteration) are
   primary methods of detection, although intrusion detection systems which actively watch for intruders are becoming more common.
3. Response - In the event of a security breach, we should have some arrangement in place to respond or recover the assets. Responses range from restoring backups through to informing appropriate concerned parties or law-enforcement agencies.

Question 24

Key points on security

Answer 24

enabling technology
power
multi-disciplinary