Exam 312-50v11 topic 1 question 55 discussion

Meet-in-the-Middle Attack on Digital Signature SchemesA meet-in-the-middle attack is the best attack method for cryptographic algorithms using multiple keys for encryption.This enables the attacker to gain access to the data easily compared with double DES. (P.3119/3103)

In a meet-in-the-middle attack against DES, an attacker tries to find a pair of keys that produce a specific known plaintext-ciphertext pair. The attacker encrypts the plaintext with all possible keys and stores the results in a table. Then, they decrypt the ciphertext with all possible keys and match the results from both processes to find a pair of keys that yield the desired known plaintext-ciphertext pair. This attack shows that using two separate keys for encrypting and then decrypting a message is not significantly more secure than using a single key, as the attacker can find a pair of keys that achieves the same result as a single key.

Meet-in-the-middle attack is attack on Digital encryption standard, breaking the encryption process into simpler, separate steps instead of one long, complex chain. It is executed to decode multiple DES.

Answer :- B keyword is 'Plainext'

The meet-in-the-middle attack (MITM), a known plaintext attack, is a generic space–time tradeoff cryptographic attack against encryption schemes that rely on performing multiple encryption operations in sequence. The MITM attack is the primary reason why Double DES is not used and why a Triple DES key (168-bit) can be brute-forced by an attacker with 256 space and 2112 operations

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