Assignment 19

Sections 8.1 and 8.2 introduced the concepts of has functions, which luckily I'd already encountered in PIC 10a so the concept was familiar. The cryptographic applications of hash functions were determined to be based on 3 principles, the third of which, that two messages that produce the same hash output is hard to find, is by far the hardest to verify as was seen by the example in section 8.2, where it was scarcely done. The most difficult part of these sections was visualizing a function that releagates a message of any length into a hash output of fixed length that gives meaning information. The example of a digital signature was the application that stuck out to me the most, but as far as cryptography is concerned, it seems infeasible to take a message m, send it to h(m) and then get m back out (which is the point) so as a cryptosystem hash functions seem unavailable.

As previously mentioned, one of the prominent uses of hash functions for cryptographic purposes, is in the form of a digital signature. If the 3rd principle is indeed satisfied, the hash function works as signature verification and error checking, both of which are paramount in cryptosystems sincce eve can presumably tamper with a message or possibly create her own.