What is a brute-force attack?

A brute-force attack is a method used in cryptography to gain unauthorized access to encrypted data or systems by systematically trying every possible key combination until the correct one is found. This attack exploits the fact that, despite the strength of encryption algorithms, the keyspace (total number of possible keys) can be exhaustive. Therefore, given enough time and computational power, an attacker can eventually discover the key that unlocks the encrypted data.

In essence, this method does not rely on any insight into the algorithm itself or any weaknesses within it; rather, it assumes that each key is equally likely. The main challenge lies in the time and resources required, as the larger the key size, the longer it would take to successfully perform a brute-force attack.

The other options do not accurately capture the essence of a brute-force attack. Enhancing encryption algorithms relates to improving security measures rather than attacking them. Phishing attacks are social engineering tactics aimed at tricking users into providing sensitive information, which is unrelated to the mechanics of brute-force attacks. Lastly, data backup security focuses on protecting data copies rather than attempting to compromise encryption directly. Therefore, the definition that highlights the exhaustive key-trying approach is indeed the correct one.