Question

Demonstrate how you can construct an Iterative Hash h function using the Merkle- Damgard Design. Use as your compression function f:{0, 1}^v times {0, 1}^b rightarrow {0, 1}^v, AES with 512-bit keys. Explain what the values of v and b will be in your compression function and where in the block cipher (AES) are you using the blocks of the message you want to hash. Using the iterative hash function you just create above, show how a digest for a 1536-bit long message will be produced. Finally explain how you can use the Hash function h you created above in order to generate a MAC. What is the name of the main security property we care about in MACs and how is it defined? Explain whether and why the following construction for a MAC is good: H_k(m) = h(k||m) where: H_k(m) the MAC of message m using secret key k and h the Hash function you create in the first step of this question. (||is the symbol for string concatenation).

Answer 1

Answer: Explain what is the value of v and b in block cipher (AES): . To send the single 512 bits message to another users at the some points in the process . So v and b is 512 value for the block cipher in AES Iterative hash function: Let us consider message digest(MD): » The MD family comprises of hash functions MD2, MD4, MD5 and MD6. It was adopted as Internet Standard RFC 1321 o o It is a 512-bit hash function. o MD5 digests take generally used in the software creation to provide word about integrity of relocated file o Usually the block sizes are from 128 bits to 512 bits The Mac of message m using secret key kand h: * o In the mac of messag, the data blocks are connect to the mathematical or exact hash function to the main hash value operates o The hashing algorithm are rounds in the hash function process like block cipher system o Separately round takes the inputs secure size normally of the most current message block and production of the last round process