Question

Discuss double DES? What is the idea behind meet in the middle attack?

Answer 1

The meet-in-the-middle attack (MITM) is a generic space–time tradeoff cryptographic attack against encryption schemes which 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 bruteforced by an attacker with 256 space and 2112 operations.