IBDP Computer Science A2.4 Network security HL Paper 2 - New Syllabus

(a)
For the correct answer:

• The data record can be locked as soon as one officer opens it in edit mode or begins a transaction.
• The second officer would have read-only access and would not be allowed to edit the record until the first officer has completed the update.
• The lock can be removed when the edit is complete, or after a specified timeout period.
• Locks may also be applied and removed in two phases to ensure that transactions occur in a serial sequence, known as two-phase locking.

Explanation: Data locking prevents two users from modifying the same record simultaneously, avoiding conflicting updates and maintaining data consistency.

(b)
For the correct answer:

Advantages:

• Eliminates duplicate data and reduces update anomalies.
• Improves the integrity and consistency of crime data.
• Allows quick access to and sharing of data between different law enforcement agencies.
• There is no need to search multiple independent sources, reducing the time required to investigate crimes.
• Crimes committed in different regions can be cross-referenced, improving the accuracy of investigations.
• A centralized database can contain a larger amount of historical data, providing greater insight for data analysis.

Disadvantages:

• A single central database can be targeted by hackers, potentially causing major data loss or privacy breaches.
• The central computer is a single point of failure, so system failure could cause downtime and hinder crime investigations.
• Increased bureaucracy and security clearance requirements may prevent timely access to crime data.
• Data transmitted to and from the central database could be intercepted, potentially compromising investigations and privacy.
• Development and maintenance costs can be high because of the hardware, security and transmission infrastructure required.

Conclusion: A centralized crime database can significantly improve data sharing, consistency and the ability to cross-reference crimes, but this must be balanced against the security risks, potential system failure and high infrastructure costs.

(c) (i)
For the correct answer:

Data mining uses pattern-recognition techniques to identify trends, relationships and useful information within a large dataset.

• It can identify hidden patterns and correlations within crime data.
• Historical crime data can be analysed to reveal trends in crime type, location or time.
• Relationships and associations between different entities can be identified using techniques such as link analysis.
• Data mining can identify anomalies or outliers in crime data.
• Predictive models can be developed from historical crime data to help predict future crime patterns.

Example: A police database could be analysed to identify a pattern showing that particular types of crime frequently occur in a specific location at a particular time. This information could then be used to predict where and when similar crimes may occur.

(c) (ii)
For the correct answer:

Data matching compares different sets of data to identify records or entities that correspond to each other or share similarities.

• It can identify records referring to the same entity, such as a suspect, vehicle or location.
• Data can be matched across multiple databases to identify relationships between records.
• Apparently unrelated crimes can be grouped together when they contain matching information.
• The results can be used to reveal connections between past and present crimes.

Example: CCTV data could show the same vehicle being present at the locations of several different crimes. Matching the vehicle registration information could link the separate investigations and help police identify a possible connection.

Other valid examples include matching physical characteristics of a suspect to several crimes, detecting aliases used by the same criminal, or linking individuals together to identify a possible crime syndicate.

(d) (i)
For the correct answer:

• A password can be vulnerable to a dictionary or brute-force attack, particularly if users choose weak passwords containing common words, letters or numbers.
• Users may reuse the same password for multiple systems, so a password obtained from one compromised system could be used to access the police database.
• A leaked, written-down or obvious password could be obtained by an attacker.
• Keylogging could be used to capture the password as it is entered.
• A password may be vulnerable to a man-in-the-middle attack if the communication is not encrypted.
• Without two-factor or multi-factor authentication, obtaining the password alone may be sufficient to gain access.

(d) (ii)
For the correct answer:

• Legislation provides a framework requiring organizations to store and process personal data fairly and lawfully.
• Organizations may be required to register with or comply with requirements established by a data protection authority.
• Financial penalties can be imposed on organizations that fail to comply with data protection requirements.
• Personal data should be retained only for the period of time that is necessary.
• Data should be used only for the intended purpose for which it was collected.
• Personal data should not be shared with other organizations or countries without appropriate permission or legal justification.
• Individuals can be given the right to view the data held about them.
• Organizations should store data that is adequate, relevant and not excessive.
• Organizations should ensure that stored personal data is accurate and kept up to date.