The use of cryptographic algorithms is one of the most important elements nowadays in many computer security services and applications. a) A secure hash function is an important algorithm used for message authentication and digital signatures i. Describe the preimage resistance property(ies) necessary for such functions to be useful for message authentication. [10 marks] ii. Which level of effort is required to ensure collision resistance against brute-force attacks for a hash code of length b ? [5 marks]