A basic overview of what blockchain is with step-by-step easy to follow explanation of its core concepts. It should be easy for anyone with zero knowledge of blockchain to follow through the slides

1. Blockchain
Presented by Rakib
References:
https://anders.com/blockchain/
https://anders.com/blockchain/blockchain.html
https://blockchaindemo.io/

2. Myth-Busters
● Blockchain doesn’t mean crypto-currency
● Crypto-currency doesn’t mean BitCoin or Ethereum
--------------------------------
● Blockchain is just a technology. ex: database | cache | etc
● Crypto-currency uses an implementation of blockchains
● BitCoin, Ethereum these are all different kinds of
crypto-currencies which use different ways of
implementing the Blockchain

3. A chain is only as strong as its weakest link

4. A block
Index
Data
Hash
Nonce
Previous Hash
Difficulty Level Miner

5. What is a hash?
A scrambled representation of a value which is hard to
reverse to determine the original value that it represents.
h = f(x)
Popular hashing functions:
sha1 | sha256 | md5 | AES | bcrypt | many more

6. “hello world”
sha1
sha256
md5

7. “hello world”
sha1 2aae6c35c94fcfb415dbe95f408b9ce91ee846ed
sha256
b94d27b9934d3e08a52e52d7da7dabfac484efe3
7a5380ee9088f7ace2efcde9
md5 5eb63bbbe01eeed093cb22bb8f5acdc3

8. “hello world” “Hello world”
sha1 2aae6c35c94fcfb415dbe95f408b9ce91ee846ed 7b502c3a1f48c8609ae212cdfb639dee39673f5e
sha256
b94d27b9934d3e08a52e52d7da7dabfac484efe3
7a5380ee9088f7ace2efcde9
64ec88ca00b268e5ba1a35678a1b5316d212f4f3
66b2477232534a8aeca37f3c
md5 5eb63bbbe01eeed093cb22bb8f5acdc3 3e25960a79dbc69b674cd4ec67a72c62

9. Back to the chain

10. It always starts with
a block
-
the GENESIS block
● index = 0
● no previous hash

11. The Data
The data can be any
data representing
any event or any
information that
happened in the
world

12. the hash is
produced by
hashing the data
and the nonce
hash = f(data+nonce)
The Hash
Disclaimer: The hash is actually computed from a
combination of several fields like:
(data + nonce + index + previous hash + timestamp).
But for the simplicity of these slides, we will only consider
(data + nonce).

13. The nonce is
determined by
the miner ,
incrementally until
the hash meets a
pre-defined.
difficulty level .
The Nonce

14. hash = f(data + nonce)
Difficulty Level: ‘$0000’
f(‘hello world’ + 1) = 7b502c3a1f48c8609ae212cdfb639de……
f(‘hello world’ + 2) = 2aae6c35c94fcfb415dbe95f408b9ce……
f(‘hello world’ + 3) = b94d27b9934d3e08a52e52d7da7dab……
f(‘hello world’ + 245) = 3e25960a79dbc69b674cd4ec67a7……
f(‘hello world’ + 9436) = 5eb63bbbe01eeed093cb22bb8f……
f(‘hello world’ + 85460) = 0000a51677b3cc64056c498c1d……

15. ● the data contains any new
information / event
● increments the index by 1
● determines a new nonce
to validate a new hash for
the new data
● previous hash refers to
the hash of the previous
block - which 1 index less
Enter next block

17. ● There is one genesis block
● Every other block follows the genesis block sequentially
● Every block knows the hash of its previous block
● Modify the data in one block:
○ it changes its own hash
○ which invalidates the value of ‘previous hash’ in the
next block
○ which invalidates the next block’s own hash
○ the whole chain collapses following that one block
One chain of many blocks

18. A chain is only as strong as its weakest link

19. Demo
https://anders.com/blockchain/blockchain.html

20. Some pointers
An immutable record of the past
Historical events cannot be changed easily
Democratically determine problematic peers
Can use public-private keypair-signing to further
reinforce integrity of the blockchain

21. Further illustrated video tutorials
https://anders.com/blockchain/

22. Thanks
Syed Rakib Al Hasan
Software Engineer
fave Malaysia
github.com/syedrakib
linkedin.com/in/syedrakib
twitter.com/syedrakib