CONSTRUCTION 5.3 Let (Gen, h) be a fixed-length hash function for inputs of length 2n and with output length n. Construct hash function (Gen, H) as follows: e Gen: remains unchanged H: on input a key s and a string x E {0, 1}* of length L ? 2", do the following: 1. Set BL 1.e e number O zeros so its length is a multiple of n. Parse the padded result as the sequence of n-bit blocks x1, where L is encoded as an n-bit string. ... ,XB. Set xB+1-L, 2. Set zo:-0n. (This is also called the IV 3. For i-1,... , B +1, compute zih*(2i-1|Ixi,) 4. Output zB+1 The Merkle-Damgrd transform CONSTRUCTION 5.3 Let (Gen, h) be a fixed-length hash function for inputs of length 2n and with output length n. Construct hash function (Gen, H) as follows: e Gen: remains unchanged H: on input a key s and a string x E {0, 1}* of length L ? 2", do the following: 1. Set BL 1.e e number O zeros so its length is a multiple of n. Parse the padded result as the sequence of n-bit blocks x1, where L is encoded as an n-bit string. ... ,XB. Set xB+1-L, 2. Set zo:-0n. (This is also called the IV 3. For i-1,... , B +1, compute zih*(2i-1|Ixi,) 4. Output zB+1 The Merkle-Damgrd transform