Blockchain Technology What is Blockchain?? what is Block? what is chain? What is hash? Blockchain Concept Blockchain futures

1. BLOCKCHAIN TECHNOLOGY
Presenter
Delwar Alam
Security Researcher, Bugsbd Ltd.
Founder ,SQLiWiki

2. Agenda
 Block
 Blockchain Concept
 Blockchain Futures
 Hash
 Digital Signature
 Example

3. Block
A block is the current part of a blockchain which records some or all
of the recent transactions goes into blockchain as permanent database.
Figure 1.0 : Block
DATA
HASH
PREVIOUS
HASH

4. Block
3 PARTS
SENDER RECEIVER
DIGITAL
SIGNATURE
Hi Hi
Figure 1.1 : Block

5. Block
A
DATA
HASH
P.HASH
Hi Hello How are you ?
0x00253111 0x00253112 0x00253113
0x0000000 0x00253111 0x00253112
B CGenesis
Block
Figure 1.2 : Block

6. Blockchain
A blockchain is a decentralized and distributed digital ledger that is
used to record transactions across many computers .
First described in 1991 by Stuart Haber and W. Scott Stornetta.
Conceptualised by Satoshi Nakamoto in 2008
Figure 2.0 : Blockchain

7. Hash Vs Previous Hash
?
What about the
HASH &
PREVIOUS HASH ?
Figure 2.1 : Hash and Previous Hash

8. Hash
Input data, applying some algorithm to it, and generating a fixed-size
output data called the hash. The input can be any number of bits that could
represent a single character, an MP3 file, a spreadsheet of your banking
history or even the entire Internet.
Figure 2.2 : Hashing
Input Data
Hashing
Algorithm
Output
Hash
256 bit
‘D’ ∞

9. Digital Signature
Digital signatures provide a means of associating a message with an
entity from which the message has been originated. Digital signatures are
used to provide data origin authentication and nonrepudiation.
Message Encrypt
Message by
Private Key
Message
+
Signature
Hashing
Function
256 bit
Sender Receiver
Figure 2.3 : Digital Signature

10. Types of blockchain
It can be divided into multiple types
Public
Private
Semi Private
Shared

11. Types of blockchain
 Public
These blockchains are open to
the public and anyone can participate
as a node in the decision-making
process. Users may or may not be
rewarded for their participation.
These ledgers are not owned by
anyone and are publicly open for
anyone to participate in.
Figure 3.0 : Public Blockchain

12. Types of blockchain
 Private
Private blockchains as the
name implies are private and are
open only to a consortium or group
of individuals or organizations that
has decided to share the ledger
among themselves.
Figure 3.1 : Private Blockchain

13. Types of blockchain
 Semi Private
Here part of the blockchain is
private and part of it is public. The
private part is controlled by a group
of individuals where as the public
part is open for participation by
anyone.
Figure 3.2: Semi - Private Blockchain

14. Types of blockchain
 Shared
This is generic term that is
used to describe any application or
database that is shared by the
public or a consortium.
Company A Company B
Figure 3.3 : Shared blockchain

15. Network Diagram
It can be divided into Three types
 Centralized
 Decentralized
 Distributed

16. Network Diagram
 Centralized
This is a core concept and benefit
of blockchain. There is no need for
a trusted third party or
intermediary to validate
transactions; instead a consensus
mechanism is used to agree on the
validity of transactions.
Figure 4.0 : Centralized network

17. Network Diagram
 Decentralized
This is a core concept and benefit
of blockchain. There is no need for
a trusted third party or
intermediary to validate
transactions; instead a consensus
mechanism is used to agree on the
validity of transactions.
Figure 4.1 : Decentralized network

18. Network Diagram
 Distributed
This ledger is distributed
among its participants and spread
across multiple sites or
organizations. This type can either
be private or public.
Figure 4.2 : Distributed network

19. 5 $
3 $
1 $
10 $
A B
CD
10$

20. Blockchain Future
The blockchain is radically changing the future of transaction based industries.
Figure 5.0 : Blockchain Future

21. Example
Bitcoin
 Bitcoin is an online cryptocurrency
 It’s not a technology
 It’s depend on Blockchain technology
Figure 6.0 :Bitcoin

22. Example
BITCOINBLOCKCHAIN

23. Bitcoin Concept
Figure 6.1 : Bitcoin Transaction
Someone requests a
transaction Transaction broadcasted to
P2P computers (Nodes)
Miners verify the
transaction
Transaction combined to
form a data block
New block added to existing
BlockchainTransaction Complete

24. http://fintechnews.sg/9981/blockchain/blockchain-use-cases-financial-services/

25. Rafarence
• “Blockchain 101 – A Visual Demo” - https://www.youtube.com/watch?v=_160oMzblY8
• “The Truth About Blockchain”, Harvard Business Review, https://hbr.org/2017/01/the-truth-about-blockchain
• “Blockchain Basics: A Primer”, Pillsbury Winthrop Shaw Pittman LLP,
https://www.pillsburylaw.com/images/content/1/0/v2/104160/AdvisoryMay2016CSTechBlockchainBasicsAPrimer.pdf
• “Blockchain: The Invisible Technology That’s Changing the World”, PC Magazine, Feb 6, 2017,
http://www.pcmag.com/article/351486/blockchain-the-invisible-technology-thats-changing-the-wor
• “Bits on Blocks”, Blog by Antony Lewis, https://bitsonblocks.net/
• “Blockchain and Smart Contract Automation”, PwC Technology Forecast, http://www.pwc.com/us/en/technology-
forecast/blockchain.html

26. Any Question??

27. Thank You