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.