Capability-based security in Operating Systems - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the primary purpose of capability-based security?

Capability-based security is a model used in operating systems and software design. What is its main goal?

A To control access by associating unforgeable tokens with permissions

B To encrypt all data stored on a device

C To authenticate users using passwords only

D To monitor network traffic for suspicious activity

💡 Hint

Think about how access rights are given and checked in capability systems.

Capability-based security uses tokens called capabilities that are unforgeable and specify what actions are allowed. This controls access directly.

📋 Factual

intermediate

Which of the following best describes a capability in capability-based security?

Choose the option that correctly defines a capability.

A A password used to log into a system

B A list of all users in a system

C A firewall rule blocking unauthorized access

D A key or token that grants specific access rights to an object

💡 Hint

Capabilities are related to permissions and access control.

A capability is a key or token that grants specific access rights to an object, allowing the holder to perform certain operations.

🔍 Analysis

advanced

How does capability-based security differ from traditional access control lists (ACLs)?

Consider the differences between capability-based security and ACLs. Which statement correctly highlights a key difference?

A Capabilities are stored with the object, while ACLs are stored with the user

B Capabilities are unforgeable tokens held by users, while ACLs list permissions attached to objects

C ACLs allow delegation of rights easily, capabilities do not

D ACLs require encryption, capabilities do not

💡 Hint

Think about where permissions are stored and how they are checked.

In capability-based security, the user holds unforgeable tokens (capabilities) granting access. In ACLs, the object stores a list of users and their permissions.

❓ Reasoning

advanced

Why are capabilities considered unforgeable in capability-based security systems?

What makes capabilities unforgeable, ensuring security in capability-based systems?

A They are stored in a public database accessible to all users

B They are simple strings that users can copy freely

C They are encrypted with a secret key only the system knows

D They are printed on paper and physically handed out

💡 Hint

Consider how the system prevents users from creating fake capabilities.

Capabilities are often implemented as tokens encrypted or protected by the system so users cannot create or alter them without authorization.

🚀 Application

expert

In a capability-based system, if a user wants to delegate access to a file to another user, what must they do?

Given a capability-based security model, how does a user safely delegate access rights to another user?

A They must copy and securely transfer the capability token to the other user

B They must add the other user to the file's access control list

C They must share their password with the other user

D They must request the system administrator to grant access

💡 Hint

Think about how capabilities represent access and how they can be passed.

Delegation in capability systems happens by passing the capability token itself, which grants the rights to the recipient.