Question

3-DES (with three different keys) provides 168 bits of security strength. True or False

Answer 1

False. 3-DES provides a security strength of 112 bits, not 168 bits.

Step-by-step explanation:

False.

3-DES, or Triple Data Encryption Standard, provides a security strength of 112 bits, not 168 bits. Each key in 3-DES is 56 bits long, but due to the meet-in-the-middle attack, the effective security strength is reduced to 112 bits.

For example, if an attacker knows the plaintext and the corresponding ciphertext for a specific encryption using 3-DES, they can exhaustively run through all possible keys to find a pair of keys that produce the same intermediate ciphertext. This attack reduces the effective security strength by half.