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Security- Hash Functions

Here we go again bloggers !!

It's time to learn some security basics with HASH Functions.

It's not what you think It's something good more than HASH.

No more jokes!
Dive in


A "hash function" is a function that converts the data it's given into an irregular value of fixed length.
A hash Function might be easier to understand if we imagine it as blender




                                             When we input data into a hash function..

                                                        It outputs an irregular value
If we imagine a hash function as a machine that blends up data,it's easier to understand.The irregular output from a hash is called a "hash value". Hash values are numbers, but are often written in hexadecimal.



Computers manage all data in binary which uses 0s and 1s.


Hash values are also data, and are manged in binary.

What a hash function is actually doing is performing some value calculations inside the computer.
Let's look at some features of hash functions from this premise



Their 1st characteristic is that the data values they output are of fixed length
The length of their output data varies according to the hash function.In the case of SHA-1, for example,it's fixed at 20 bytes.


Even when extremely large amounts of data are input, the output hash value data doesnt vary in length

Even when extremely large amounts of data are input, the output hash value data doesn't vary in length.



Likewise, no matter how small the input the length of the hash value data is the same.






A 2nd characteristic is that if given the same input, they will invariably produce the same output.







A 3rd characteristic is that if similar data is input, even if different by only 1 bit, their output greatly differs.









It is not the case that if similar data is input, the hash values will be similar, too.



A 4th characteristic is that even if completely different data is input, it does happen that identical hash values are produced ,low as the chances may be.





This called a "hash collision".





A 5th characteristic is that converting hash values back into their original data is,in reality, impossible.




Impossible

The flow of input and output is one way which is a big difference from "encryption".



One final characteristic that can be given is that their calculations are relatively simple.




There are a number of hash function algorithms, but currently it is most common to use "SHA-2".



hash functions can be said to output a summary of the data input, and are used in many situations.

Examples of hash function usage are explained in detail in the "Message Authentication Codes" and "Hash Tables" entries of this article.


That's it for this article 
Hope you find something useful 


-ThilanJR10-















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