MD5 produces how many possible hash values?

• A. 2^128
• B. 2^160
• C. 2^64
• D. 2^256

Answer: (A)

MD5 outputs a fixed 128-bit hash, so the hash space consists of 2^128 possible values. In practice, MD5 hashes are shown as 32 hexadecimal characters, because 32 hex digits × 4 bits each equals 128 bits. The other options correspond to other hash functions (SHA-1 is 160-bit, SHA-256 is 256-bit), or an unrealistically small size. So the number of possible hash values is 2^128.