Which attack method uses known plaintext to determine the key of ciphertext?

The attack method that uses known plaintext to determine the key of ciphertext is a Known Plaintext Attack. This type of attack occurs when an attacker has access to both the plaintext (the original unencrypted data) and the corresponding ciphertext (the encrypted data). By analyzing the relationship between the known plaintext and its ciphertext, the attacker can deduce information about the encryption key or the encryption algorithm itself.

In a Known Plaintext Attack, the attacker typically seeks to exploit any patterns or weaknesses within the encryption algorithm. This can involve comparing the known plaintext to the ciphertext to find similarities or regularities that may reveal clues about the key. Such attacks are particularly effective against certain encryption methods that may not be robust against this type of analytical approach.

The other attack methods listed, while they relate to cryptographic attacks, do not specifically rely on the knowledge of both plaintext and ciphertext in the same manner as a Known Plaintext Attack. For example, frequency analysis focuses on the frequency of letter occurrences in the ciphertext without relying directly on known plaintext. A dictionary attack works by leveraging a predefined list of likely passwords or phrases, generally without regard to how they relate to specific ciphertext. Lastly, a brute force attack involves systematically trying every possible key until the correct one is found, rather