Which type of attack tries every possible key until intelligible plaintext is obtained?

• A. Brute-force attack
• B. Man-in-the-middle attack
• C. Phishing attack
• D. DDoS attack

Answer: (A)

A brute-force attack is a method used to gain unauthorized access to encrypted data by systematically checking all possible keys until the correct one is found, allowing the attacker to decrypt the information. This type of attack is exhaustive and can be very time-consuming, especially with strong encryption methods that use long keys. The fundamental principle behind a brute-force attack involves trial and error; the attacker does not rely on any weaknesses in the encryption algorithm itself but rather on the sheer computational power to test combinations until they achieve success.

In contrast, other options focus on different attack methodologies. A man-in-the-middle attack involves intercepting and possibly altering the communication between two parties without their knowledge. Phishing attacks are aimed at deceiving individuals into providing their sensitive information, often via fraudulent emails or websites. Distributed Denial of Service (DDoS) attacks aim to overwhelm a system with traffic to make it unavailable, rather than trying to decrypt data.

The distinction lies in the mechanics of the brute-force approach, which relies purely on persistence rather than exploiting vulnerabilities, making it a key topic in information security discussions around data protection and encryption integrity.