Why is merkle-Damgard needed? s The need for collision-resistant hashing has been a long-time goal of modern cryptography. .The problem: find a hash function that has S An input of variable length x An output of fixed length 2020 ❖The need for collision-resistant hashing has been a long-time goal of modern cryptography. ❖The problem: find a hash function that has: ❖An input of variable length; ❖An output of fixed length. Why is Merkle-Damgard needed?