## Continuing our series of Research and Study over the Bitcoin Blockchain
#
Today we'll start delving deep into the realm of hashing algorithms. We'll cover the hashing algorithm used in Bitcoin, i. e. SHA256 as well as X11, a chained hashing solution of 11 different hashing algorithm and finally X17, the longest hashing algorithm so far.

![sat.png](https://steemitimages.com/DQmcPkWmKNAb17h863rsi4msiBWAaqAkunJYzehJTSQtPFc/sat.png)

## First, let's understand what is a Hash Function
It is any function used to map data into data. It's a serialization of overlapping signatures for a very large sum of descriptions. A hash function is a way to provide valid signatures for any given initial set of data.

### Here are a few resources to help understand the concept

- #### Simple Simple and Fast Explanation
https://youtu.be/yXmNmckX4sI

- #### MIT Lecture with full advanced concepts
https://youtu.be/KqqOXndnvic

From this we point out:

- A hash function is a map of data  to a fixed length output (usually a hexadecimal number: e. g. d68e72c200e82c2c200e82c)
- It is deterministic, public and as "random" as it gets
- Not linear. Not O(1)

### X11 and X17
X11 is a chain of eleven hash functions and X17 uses, (guess how many?)  seventeen hashes chained: blake, bmw, groestl, jh, keccak, skein, luffa, cubehash, shavite, simd, and echo.

## This is part of a series of deep study over the bitcoin blockchain

For interested parties, here is the first article of this series: https://steemit.com/bitcoin/@bitworkers/deep-study-of-bitcoin-code-series-the-times-03-jan-2009-chancellor-on-brink-of-second-bailout-for-banks

#### References
- https://en.wikipedia.org/wiki/Hash_function

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EDUARDO CAPANEMA
@bitworkers