Merkle-Damgard hash function Transforms a collision resistant compression function compress 0,1ym+t→10,1ym to a collision resistant hash function U=m+1{0,1y→0,1m19 Merkle - Damgard hash function Transforms a collision resistant compression function: – compress: {0,1}m+t → {0,1}m to a collision resistant hash function. – Ui = m+t+1 {0,1}i → {0,1}m