Your manager is considering purchasing a message authenticat

Your manager is considering purchasing a message authentication system. She is considering 3 different systems. One system uses MD5 hashing, another uses SHA2 hashing and the other system uses a brand new hashing algorithm called VSH (Very Smooth Hash). You have been asked to prepare an executive summary (i.e. clear and concise) that describes the attributes of each algorithm and the pros and cons. You should consider reviewing each algorithm along the same primary dimensions and then focus on differentiating factors where appropriate.

What would your recommendation be and why?

Solution

All the three mentioned message authentication system are nothing but hashing techniques.Hashing is a technique to convert a range of key values into a range of indexes of an array so that retrival of elements from array or any data structure ( like tree, list etc.) can be done through indexs value instead of key beacuse key is the important data which we donot want to share with anyone specially to outerword.
i.e We cannot share the password over the network beacuse if we do so then anyone (hacker ) will easily trace the data packets over the network and find out the key or password. so the idea is to sent the encrpted value of the password instead of the actual one.

MD5 - The MD5 alogorith used hash function producing a 128-bit hash value. MD5 hashing algorithum intially solved the problem to share the useful information over the network or outer world but latter on found that MD5 hashing technique is suffering from extensive vulnerabilities i.e a collision attack. A collision attack on a cryptographic hash tries to find two inputs producing the same hash value so as an better alternative SHA (Secure Hash Algorithm) hashing technique came into the picture.

SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions. Cryptographic hash functions are mathematical operations run on digital data; by comparing the computed \"hash\" (the output from execution of the algorithm) to a known and expected hash value.

A key aspect of cryptographic hash functions is their collision resistance: nobody should be able to find two different input values that result in the same hash output.Collision resistance is a property of cryptographic hash functions: a hash function H is collision resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b such that H(a) = H(b), and a b.
This is big advantage the computer worl found over the MD5 alogoritum.

disadvatage of SHA-2 technique we need to understand first VHS ( Very Smooth Hash)

VSH - In cryptography, Very Smooth Hash (VSH) is a provably secure cryptographic hash function. Provably secure means that finding collisions is as difficult as some known hard mathematical problem.There are lots of advantage of VHS technique like

1. VSH can be useful in embedded environments where code space is limited.
2. The message length does not need to be known in advance.
3. Thus VSH is (strongly) collision-resistant,
4. VSH seems quite suitable in practice for constructing \"hash-then-sign\" RSA signatures for arbitrarily long messages. However, such a signature must be   designed carefully to ensure its security.