Take this Quiz: A-Level Computer Science: Security, Data and Consequences | Zestly

Question 1

Two parties, a client and a remote server, need to establish a secure connection but have never met and cannot share a secret key beforehand. Which method allows them to exchange a key safely, and why?

Accepted Answer

Asymmetric encryption, because it allows the client to encrypt data with a public key that only the server can decrypt with its private key.

Answer

Asymmetric encryption, because it is simply a stronger, more modern version of symmetric encryption that requires no key exchange.

Answer

Symmetric encryption, because it is faster than asymmetric methods and therefore inherently more secure for initial handshake protocols.

Answer

Symmetric encryption, because it uses a single key that is mathematically impossible to intercept during the initial exchange.

Question 2

A developer is designing the login module of a new application. Rather than storing each password, the system stores the result of putting the password through a one-way function. What property of that function makes this the right choice?

Accepted Answer

It is computationally infeasible to reverse, so the stored value cannot be turned back into the password, and a copy of the database does not hand anybody the passwords themselves.

Answer

It shortens every password to a fixed length, which saves space in the table and is the main reason it is preferred.

Answer

It produces a different value every time the same password is processed, so a stolen value is of no use to anyone.

Answer

It is encryption with the key thrown away, so the original password could still be recovered if the key were ever found again.

Question 3

A database stores user credentials. Two users, Alice and Bob, both choose the password 'Password123'. The system stores different values for each user. What is the primary purpose of the salt added to these passwords?

Accepted Answer

It ensures that identical passwords result in unique stored values, preventing the use of precomputed tables to identify common passwords.

Answer

It ensures that the password is changed automatically by the system every time the user logs in.

Answer

It increases the length of the password to ensure it meets modern complexity requirements for system security.

Answer

It acts as a secondary encryption layer that requires a unique key for every single user in the database.

Question 4

A user visits a website and their browser displays a digital certificate. What does this certificate actually establish, and what is a common misconception about it?

Answer

It proves that the organisation behind the website is legally compliant and has been vetted for ethical business practices by a third party.

Answer

It guarantees that the website is free from malware and that all data transmitted will be completely immune to interception.

Answer

It confirms that the website is the most popular or reliable source for the information provided, as verified by the certificate authority.

Answer

It establishes that the website's public key belongs to the entity named in the certificate, but it does not prove the organisation is honest or trustworthy.

Question 5

A web application takes a username from a form and inserts it into a database query. The developer switches to using parameterised queries. How does this change the way the input is treated?

Answer

It forces the database to check the input against a list of known malicious commands before executing the query.

Answer

It encrypts the user input before it reaches the database, ensuring that any malicious code is rendered unreadable.

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It ensures that the input is treated strictly as data and never as part of the executable command structure of the query.

Answer

It automatically removes all special characters from the input to prevent the database from misinterpreting the user's intent.