Why is 3DES stronger than DES?

• A. It uses three keys
• B. It uses a larger block size
• C. It uses a stronger random number generator
• D. It provides authentication

Answer: (A)

The key factor that makes 3DES stronger than DES is the expansion of the keyspace through triple encryption with multiple keys. DES uses a 56-bit key, so a brute-force search would have to try about 2^56 possibilities. Triple DES encrypts data three times, typically with three independent keys, which multiplies the number of possible key combinations dramatically. With three distinct keys, the effective key length can reach up to 168 bits, making exhaustive searching far more impractical. The block size remains the same, and 3DES does not inherently add authentication, so the strength gain comes from the much larger keyspace rather than changes to block size or authentication capabilities.