SHA

SHA stands for Secure Hash Algorithm. It is a way to encode data with an asymmetric data encoding function. There are many implementations of this class of algorithms, generally known as SHA-0,SHA-1,SHA-2,SHA-3.

A Shattered SHA-1 Function

It is public knowledge that Google had cracked SHA-1 and presented a website called:shattered.io to disclose their findings. You can even test if your document encoded using SHA-1 has name collisions or not. Name collision is a situation where names chosen by Secure Hash Algorithms (SHA) to represent a specific data object maybe shared by two different data objects. This name collision problem could allow one to submit a fake document or fake data object that has the same digital digest (the name), therefore confound the authenticity of information. An example of name collision can be found on shattered.io.

Particularly useful tutorial

It would be good to read up on this website.