Bitcoin is a cryptocurrency that uses blockchain technology to record transactions. Transactions are grouped into blocks and added to the blockchain through a process called proof-of-work that requires significant computing power. Miners who solve the proof-of-work puzzles and add blocks to the blockchain are rewarded with new bitcoins and transaction fees. The blockchain prevents double spending by ordering transactions and ensuring bitcoins cannot be spent twice. As more blocks are added, transactions are confirmed, though single transfers occur instantly. A maximum of 21 million bitcoins will ever be created through mining rewards.
Is cryptocurrency really the future of money? Bitcoin is the first and most famous cryptocurrency that exploded in late 2013 when the price per Bitcoin exceeded $1200. This is an explanation of what cryptocurrency is and how payments are processed
It was my first presentation on cryptocurrency during my sophomore year in college. This presentation covers the basic understanding of cryptocurrency, working of cryptocurrency, bitcoin, blockchain and it's the difference between normal currency and cryptocurrency.
This Presentation gives an Overview of the Bitcoin Technology used today to make online transactions possible which are very secure, fast and tax-free. This shows the future scope of the Bitcoins.
Is cryptocurrency really the future of money? Bitcoin is the first and most famous cryptocurrency that exploded in late 2013 when the price per Bitcoin exceeded $1200. This is an explanation of what cryptocurrency is and how payments are processed
It was my first presentation on cryptocurrency during my sophomore year in college. This presentation covers the basic understanding of cryptocurrency, working of cryptocurrency, bitcoin, blockchain and it's the difference between normal currency and cryptocurrency.
This Presentation gives an Overview of the Bitcoin Technology used today to make online transactions possible which are very secure, fast and tax-free. This shows the future scope of the Bitcoins.
This article contains information about history of Bitcoin cryptocurrency. What is Bitcoin? Whom was it created by? This article resumes the whole history of Bitcoin since 2008 to 2018.
Blockchain in Banking, Business and BeyondMichael Novak
An introduction to Blockchain, Smart Contracts, and use cases in industries such as Digital Identification, eCommerce, Healthcare, Government, and Finance.
Welcome to our channel,
A cryptocurrency (or cryptocurrency) is a digital asset designed to work as a medium of exchange that uses strong cryptography to secure financial transactions,
control the creation of additional units, and verify the transfer of assets. Cryptocurrencies use decentralized control as opposed to centralized digital currency and central banking systems. This channel was created to share news and opportunities related to crypto space.
Check our website: https://www.everythingcrypto.club/
Join our private channel group: http://bit.ly/2YoWzFr
Follow us on social media :
Youtube : https://bit.ly/3bkoeiE
Instagram: https://www.instagram.com/everythingincrypto
Telegram : https://t.me/everythingincrypto
vkontakte : https://vk.com/public184024328
Twitter : https://twitter.com/everythingcryp5
Medium : https://medium.com/everythingincrypto
Linkedin: https://www.linkedin.com/company/everythingcrypto
what's cryptocurrency all about?
What's cryptocurrency?
What does cryptocurrency mean?
What does crypto mean?
#everythingcrypto #whatscryptocurrency #cryptocurrency #bitcoin #crypto #ethereum #freecrypto #freebitcoin #earnfreetoken #earnfreebitcoin
An introductory presentation discussing the basics of technology behind blockchain, cryptocurrency mining, and an attempt to value a cryptocurrency. Further discussion on altcoins, and a preview on ICOs.
What is cryptocurrency?, Blockchain, Bitcoin, Bitcoin Mining, Facts about Bitcoin Different types of cryptocurrencies, Cryptocurrency in India, Supreme court on cryptocurrency. Advantages and disadvantages of cryptocurrencies, Do we Invest?, Conclusion.
This Edureka Blockchain technology tutorial will give you an understanding of how blockchain works and what are blockchain technologies. This tutorial helps you to learn following topics:
1. What are Blockchain & Bitcoin
2. Blockchain Technologies
3. Peer to Peer Network
4. Cryptography
5. Proof of Work & Blockchain Program
6. Ethereum & Smart Contracts
7. Blockchain Applications and Use Cases
Michael bowen | High risk specialist |Card not present transaction expert JayWigdore
In a day that more and more banks are shying away from the risk, Go Payment Pros has continued to fight for their clients to stay profitable. Go Payment Pros can place you High Risk Merchant Account with all the risk factors in mind. They don’t just place accounts, they help keep them alive. Call Go Payment Pros today and see the difference in true High Risk Payment Proces
This article contains information about history of Bitcoin cryptocurrency. What is Bitcoin? Whom was it created by? This article resumes the whole history of Bitcoin since 2008 to 2018.
Blockchain in Banking, Business and BeyondMichael Novak
An introduction to Blockchain, Smart Contracts, and use cases in industries such as Digital Identification, eCommerce, Healthcare, Government, and Finance.
Welcome to our channel,
A cryptocurrency (or cryptocurrency) is a digital asset designed to work as a medium of exchange that uses strong cryptography to secure financial transactions,
control the creation of additional units, and verify the transfer of assets. Cryptocurrencies use decentralized control as opposed to centralized digital currency and central banking systems. This channel was created to share news and opportunities related to crypto space.
Check our website: https://www.everythingcrypto.club/
Join our private channel group: http://bit.ly/2YoWzFr
Follow us on social media :
Youtube : https://bit.ly/3bkoeiE
Instagram: https://www.instagram.com/everythingincrypto
Telegram : https://t.me/everythingincrypto
vkontakte : https://vk.com/public184024328
Twitter : https://twitter.com/everythingcryp5
Medium : https://medium.com/everythingincrypto
Linkedin: https://www.linkedin.com/company/everythingcrypto
what's cryptocurrency all about?
What's cryptocurrency?
What does cryptocurrency mean?
What does crypto mean?
#everythingcrypto #whatscryptocurrency #cryptocurrency #bitcoin #crypto #ethereum #freecrypto #freebitcoin #earnfreetoken #earnfreebitcoin
An introductory presentation discussing the basics of technology behind blockchain, cryptocurrency mining, and an attempt to value a cryptocurrency. Further discussion on altcoins, and a preview on ICOs.
What is cryptocurrency?, Blockchain, Bitcoin, Bitcoin Mining, Facts about Bitcoin Different types of cryptocurrencies, Cryptocurrency in India, Supreme court on cryptocurrency. Advantages and disadvantages of cryptocurrencies, Do we Invest?, Conclusion.
This Edureka Blockchain technology tutorial will give you an understanding of how blockchain works and what are blockchain technologies. This tutorial helps you to learn following topics:
1. What are Blockchain & Bitcoin
2. Blockchain Technologies
3. Peer to Peer Network
4. Cryptography
5. Proof of Work & Blockchain Program
6. Ethereum & Smart Contracts
7. Blockchain Applications and Use Cases
Michael bowen | High risk specialist |Card not present transaction expert JayWigdore
In a day that more and more banks are shying away from the risk, Go Payment Pros has continued to fight for their clients to stay profitable. Go Payment Pros can place you High Risk Merchant Account with all the risk factors in mind. They don’t just place accounts, they help keep them alive. Call Go Payment Pros today and see the difference in true High Risk Payment Proces
Content that helps to understand bitcoin and blockchain. Starts with currency basics, to clear the fact that bitcoin is not doing anything tangentially wrong. Followed by that bitcoin is covered and blockchain in detail.
Presentation Titled " Bitcoin and Ransomware Analysis " we discuss ransomware and how bitcoin are being utlized in cyber crime. we also have look at Bitcoin mining, Bitcoin trading market and block chain concept.
In the presentation Titled " Bitcoin and Ransomware Analysis " we discuss ransomware and how bitcoin are being utlised in cyber crime. we also have look at Bitcoin mining, trading and block chain concept.
Bitcoin - An introduction to a decentralised and anonymous currencyAndyBrodieLocima
A very short overview of Bitcoin, how it works and why it works. Starting with a definition of what a currency is, how Bitcoin relates to that definition and a bit of history, this presentation covers how Bitcoin transactions, blocks, blockchains and mining work.
The speaker share his vision on the prospects of employing the technology for practical tasks. He presented basics of the blockchain architecture with case studies of JavaScript blockchain implementation using Node.js.
This presentation by Valerii Radchenko (Senior Software Engineer, Consultant, GlobalLogic, Kharkiv) was delivered at GlobalLogic Kharkiv JS TechTalk #2 on August 17, 2018.
14 Jan17- Nullmeets -Blockchain concept decoded by Ninad SarangNinad Sarang
Introduction to Blockchain and Bitcoin technologies
Things we will cover,
* What is TRANSACTION ?
* BlockChain !!!……Never heard what is that??
* The BTC Aka BitCoins
* Who discovered?
* How it works?
* Advantages & Disadvantages
* Applications
JMeter webinar - integration with InfluxDB and GrafanaRTTS
Watch this recorded webinar about real-time monitoring of application performance. See how to integrate Apache JMeter, the open-source leader in performance testing, with InfluxDB, the open-source time-series database, and Grafana, the open-source analytics and visualization application.
In this webinar, we will review the benefits of leveraging InfluxDB and Grafana when executing load tests and demonstrate how these tools are used to visualize performance metrics.
Length: 30 minutes
Session Overview
-------------------------------------------
During this webinar, we will cover the following topics while demonstrating the integrations of JMeter, InfluxDB and Grafana:
- What out-of-the-box solutions are available for real-time monitoring JMeter tests?
- What are the benefits of integrating InfluxDB and Grafana into the load testing stack?
- Which features are provided by Grafana?
- Demonstration of InfluxDB and Grafana using a practice web application
To view the webinar recording, go to:
https://www.rttsweb.com/jmeter-integration-webinar
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Let's dive deeper into the world of ODC! Ricardo Alves (OutSystems) will join us to tell all about the new Data Fabric. After that, Sezen de Bruijn (OutSystems) will get into the details on how to best design a sturdy architecture within ODC.
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Software Delivery At the Speed of AI: Inflectra Invests In AI-Powered QualityInflectra
In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
Learn about:
• The Future of Testing: How AI is shifting testing towards verification, analysis, and higher-level skills, while reducing repetitive tasks.
• Test Automation: How AI-powered test case generation, optimization, and self-healing tests are making testing more efficient and effective.
• Visual Testing: Explore the emerging capabilities of AI in visual testing and how it's set to revolutionize UI verification.
• Inflectra's AI Solutions: See demonstrations of Inflectra's cutting-edge AI tools like the ChatGPT plugin and Azure Open AI platform, designed to streamline your testing process.
Whether you're a developer, tester, or QA professional, this webinar will give you valuable insights into how AI is shaping the future of software delivery.
Search and Society: Reimagining Information Access for Radical FuturesBhaskar Mitra
The field of Information retrieval (IR) is currently undergoing a transformative shift, at least partly due to the emerging applications of generative AI to information access. In this talk, we will deliberate on the sociotechnical implications of generative AI for information access. We will argue that there is both a critical necessity and an exciting opportunity for the IR community to re-center our research agendas on societal needs while dismantling the artificial separation between the work on fairness, accountability, transparency, and ethics in IR and the rest of IR research. Instead of adopting a reactionary strategy of trying to mitigate potential social harms from emerging technologies, the community should aim to proactively set the research agenda for the kinds of systems we should build inspired by diverse explicitly stated sociotechnical imaginaries. The sociotechnical imaginaries that underpin the design and development of information access technologies needs to be explicitly articulated, and we need to develop theories of change in context of these diverse perspectives. Our guiding future imaginaries must be informed by other academic fields, such as democratic theory and critical theory, and should be co-developed with social science scholars, legal scholars, civil rights and social justice activists, and artists, among others.
2. Overview
• What is cryptocurrency? (Introduction)
• How it works
• How to use it
• Transaction
• Security (Block Chain, Proof of work)
• Statistics
• Cryptocurrency comparisons
• It’s market and its future
• BitCoin vs LiteCoin
3. What is Cryptocurrency?
• Cryptocurrency is electronic money or virtual currency. (Online cash,
digital cur…)
• Bitcoin is one of the biggest (successful) representation of the
Cryptocurrency
• Bitcoin has no central authority (Decentralized) (P2P like torrent)
– No government involved (no bank)
• BTC can be created offline (email address)
– Anyone can create (without any permission)
– 1461501637330902918203684832716283019655932542976 (2^160)
• 21 Million Bitcoins will be created, and or mined
• Until year 2140.
– Limited or scarce like gold (Deflationary and protected from inflation)
4. Who and When?
• Bitcoin is proposed in 2008 by “Satoshi Nakamoto”
• Released Paper is found: bitcoin.org/bitcoin.pdf
• First appeared and operated on 1/3/2009
• Completely open source, so anyone can develop his
own cryptocurrency (BitCoin, LiteCoin, AltCoin…)
• Released open source: github.com/Bitcoin/Bitcoin
5. Who and When?
It’s name also been suggested that
• Samsung
• Toshiba
• Nakamichi
• Motorola
Are the founders. (But there’s no confirmation)
Satoshi Nakamoto
6. How to Use Bitcoin?
• Generate BTC address
• Connect to BTC network
• Update or download transactional block chain
• Send and receive BTC
– Offline clients:
• Install electrum, armory and hive..
– Online clients:
• Register coinbase.com, blockchain.info/wallet..
7. What is Advantage?
• Transactions transact directly with each other without using third party
(no Bank)
• Almost no processing fees
• No bank or government control
– Which means no identity revelation and no freezing account
• Transactions are computationally impractical to reverse (to protect sellers
from fraud)
• Implement escrow mechanisms (to protect buyers)
• Very difficult and expensive to hack (Hacking 10 minutes cost around half
billion USD)
8. How Does Transaction Work?
• Use digital signature for transaction (identity like real signature)
• Binds the sender’s identity to the transaction
• Detail of transaction is broadcasted to all the nodes of the p2p
network
• Receiver can get assurance from network about transaction
(balance match, not spent..) based on cryptographic proof before it
gets verified or even payed
– Owner has money in his account and didn’t spend it
• Distributed network also give assurance for double spent
9. Identity (Digital Signature)
• Bitcoin uses the digital signature to prove that
signature owner is the “account owner”
– In other words, owner owns private key
• “Private Key” is used to create the signature
• “Public Key” is used to verify the signature
– This allows anybody can verify digital signature if
they have its public key (account address)
10. Private Key
• Private key is a single unsigned 256 bit integer (32 bytes)
– Usually picked at “random”
• Needs to be secret (all the time)
– When you lose your private key, you’ll lose your all bitcoins in that
account
• Owner of the private key can spend corresponding account bitcoins
(funds)
• The private key used to generate
– “Digital Signatures”
• Signature is required to spend bitcoins (of the account)
– “Public Keys”
• Public key is used to verify signatures and generate account address
Private key
11. Public Key
• Elliptic curve multiplication function generate a public key from
private key (compressed 33 and uncompressed 65)
• No need to be secret
– Used for verifying account owner
• “Account address” is generated from public key
– Using a one-way cryptographic hash function
• Used to verify the “Digital Signatures”
– Using this digital signature he can transact bitcoin (without revealing
private key)
• Verifying digital signature, we can now that he has a private key
(owner or not)
Public key
12. Account Address
• Bitcoin address is string of digits and characters
and generated from public key
– Using cryptographic hash (SHA256)
• Shared with anyone who wants to send you
bitcoins
• User can have many addresses
– 1461501637330902918203684832716283019655932542976 (possible bitcoin addresses)
•
13. Public Key and Address
Generation
Public Key generation
using Elliptic Curve Address generation
using Hash
14. Digital Signature
• To send money (Transaction)
– User must prove that he is owner of the address
• Which means he has the private key
– To do that user generate “digital signature” from
• Transaction message
• His private key
Signature = f(private key, transaction message)
– Nodes in the network can verify using this signature that
• He is the owner of the account and
• He can spend money (from that account)
accept or reject = verify(transaction message, public key, signature)
– BitCoin Digital Signature uses
• Elliptic Curve Digital Signature Algorithm (ECDSA)
(en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm)
Transaction message is Hashed message so result will be constant.
Signature = f(private key, Hash(M))
15. Advantage of Elliptic Curve
• Shorter keys are as strong as long key for RSA
(IEEE paper)
• Low on CPU consumption.
• Low on memory usage.
• RSA relies on the hardness of factorization
(Studied for 2500 years)
• While Elliptic cure depends on discrete logarithm
(25 years of research)
17. Transaction
• Every transactions ever happened recorded on one global ledger
• To send money (Alice -> Bob)
– Account has to have enough money
• To verify money in the account
– We need to verify previous transactions
• That fund is also verified through links to previous transactions
• All transactions are written on the global ledger
• Alice has 5 bitcoins
– Means someone sent to Alice 5 bitcoins before
– “Input” should be 5 BTC
– “Output” can’t exceed 5 BTC
18. Transaction
• In fact, no records of account balances are kept
• Instead of balances, fund is verified through link to
previous transactions
• Inputs should match the balance
– To making sure that Alice can send 5 BTC
• Owning BTC means,
– There are transactions that point to your account
– And haven’t spent
20. Transaction
Real Transaction exampleInput balance should match with output
Transactions are not encrypted so it is possible to browse and view
http://blockexplorer.com
ScriptSig contains:
Signature + Public Key
Type: Address and PubKey
22. Transaction
• When you install BitCoin wallet
– It downloads every transactions
– Checks each one’s validity all the way back to the
first transaction ever made
– If you use bitcoin wallet with TOR network (which
hides IP address) you can use BTC without
revealing anything but public key
23. Double Spending (Order or
Timestamp)
• A double spend is an attack where the given set of coins is
spent more than 1 transactions
• So, there is no guarantee that first transaction comes
before second one
– Because transactions are passed through the network node-by-
node
• We can’t trust timestamp also
– Because anyone can lie about the time a transaction was
created
• This opens up the potential fraud
24. Double Spending
• Double spend (Alice->Bob)
1. Alice send bitcoin to Bob, don’t include fee
2. Receive items
3. Before transaction confirms
• Send the same bitcoin to herself include a fee
4. Miner (node) picks up the transaction with the
fee and the one without fee will disappear
(already spent)
• This will happen only if there’s same block chain
happened (Rare)
25. Double Spending
• Solution:
– BTC network records all bitcoin transfers in a
ledger (the block chain)
– And ensuring for all transferred bitcoins that
they haven't been previously spent
– Block chain:
• Is used to order transactions (TimeStamp)
• While transaction chain keeps track of how
ownership changes
26. Block Chain
• Block chain (Public Ledger) is used to order
transactions
– Ordered and timestamped record of transactions
• One block of block chain:
– Includes many transactions that considered to have
happened at the same time
• Transactions not yet in a block are called
“unconfirmed” or unordered
27. Block Chain
• Node (also computer or miner)
– Collects unconfirmed transactions into a block
– Broadcasts the block to all nodes
28. Block Chain (Book and Pages)
• Node
– Collects transactions that are happened at the same time
– And puts them into a one block
– Then link to the block chain
• If we think global ledger is the BOOK
– One block is the page of that book
– Multiple transactions listed in that page
• Miners (nodes) goal is
– Take this page
– Add to the global ledger BOOK
29. Block Chain
– To add block to the block chain
• Every transactions inside the block paired and then
hashed together like a Merkle Tree
30. Block Chain
• Every transactions hashed together like a Merkle
tree until it becomes one Merkle Root (Digest)
• Only the Merkle root included in the block’s hash
• Finally resulting one block hash combined with
the block chain (linked together)
•
Item here represents transaction
Block Chain (Digest)
New Block
31. Block Chain
• Problem
– Multiple blocks can be created at the same time
• Can’t rely on the order because they may arrive in different order
• Solution
– Vote the blocks and whichever wins will be selected
• How to vote?
– Every nodes need to solve problem in order to vote
• Which makes it difficult to vote (from fake votes)
• Proof of work
– That puzzle is called proof of work
– Which measures (proves) computing power is used or not
32. Block Chain
• In this picture,
– Three blocks are happened at the same time and
– Each node build on top of the first one it received
– Other nodes may have received the blocks in a different order and will be
generating on the first block they received.
•
33. Block Chain
– Current block link gets broken when someone solves
another block (prev picture)
– The general rule is that
• Node always immediately switch to the longest branch available.
– The Proof of Work (Reversing hash with certain threshold)
• Makes it rare for blocks to be solved at the same time (Time
Stamp)
• And even more rare for this to happen multiple times in a row.
– The probability of a single hash succeeding is:
• 0.0000000000000000000047086771693440932602401694830052
125
34. Proof of Work (POW)
• Proof of Work
– Is a economic measure to deter spam email and denial of
service (Dos) attacks
– It requires computing power before being allowed to use service
• Key feature
– Work must be hard to compute
– But easy to verify
• Bitcoin Proof of work is
– Similar to Adam Back’s Hashcash
– Used for block generation
35. Proof of Work (Bitcoin)
• Proof of work scheme is SHA-256
• And works relative to a given
– Challenge string (Hashed previous block chain)
– And proof (Nonce or random guess)
• Given challenge string, node needs to find proof that when
hashed, result begins with a number of zero bits
(Threshold).
• Hash(Proof + Challenge) = 000..0XXX..X
– Depending on the zeros computation time would be doubled
36. Proof of Work
•
Challenge
Proof of Work
When 1 zero added,
work will be doubled
Because 2^5 = 2^4 * 2
Proof Challenge
Hash
0000000…0xxxxxxxxx…x
Threshold zeros
Keep inserting
Random bits
Prev BC Hash
37. Proof of Work
When resulting zeros are 40 means 2^40 = 1099511627776
When 41 zeros means 2^40 * 2 (doubled)
38. Proof of Work
• It is impossible to switch block in the middle of the chain
– Because hash value for the new block would be different
– And reference would no longer point to it
• Which means block cannot be solved before the previous block is solved
39. Proof of Work
• After successfully solving the problem
– Block will be accepted (to the next chain)
• Difficulty of work is adjusted by network so that
block can be generated every 10 minutes
– When many miners (nodes) joined to the network
proof of work become more difficult
– Otherwise, it will become easier
• That is the reason transaction confirmation take
10 minutes on average (SAFETY reason)
40. Bitcoin Network
• The steps to run the network are:
– New transactions are broadcast to all nodes (transaction)
– Each node collects new transactions put it into a block and works on
finding a difficult proof-of-work for its block (problem solving)
– When a node finds a proof-of-work it broadcasts the block to all
nodes (block)
– Nodes accept the block only if all transactions in it are valid and not
already spent
– Nodes express their acceptance of the block by working on creating
the next block in the chain and using the hash of the accepted block
as the previous hash
41. Network (Safety)
• If two blocks are found at the same time, this will be decided by the
vote
• Vote is not one-IP-address-one-vote but rather one-CPU-one-vote
• In the network, there is other nodes (CPU) will also solve and result
(vote) will be the same as one of them
• One with the most vote will be accepted
• Modifying a past block, attacker have to redo all the proof of work
of the previous blocks
42. Network (Safety)
• Moreover, when two different blocks are found, nodes work on the first
one they received, but save the other branch in case it becomes longer
• Link will be broken when the next POW is found and other link becomes
longer
• And nodes that are working on the other branch will then switch to the
longer one.
• Majority of decision is represented by the longest chain, which has the
greatest POW effort invested
• Outrunning block chain is same as the winning the lottery many
consecutive times
– Because hash is collision resistance (Hard to find)
43. Network (double spending)
• For attackers perspective:
– Attacker needs to get input from previous block and add his own
(fake) transaction.
– Then compute the next blocks until he catches the honest block
chain.
– Honest chain generates new block every 10 minutes.
– The race between the honest chain and attacker chain can be
characterized as a Binomial Random Walk.
– Probability is analogous to a Gambler’s Ruin problem
Waiting for 10 minutes makes transaction more secure!
44. How Bitcoin is Generated?
• Reward is given to whoever solves a block
• Which means
– Whenever miners succeed, they are allowed include in that transaction block
special transaction for themselves.
• That is coin-based transaction and this is how new coins get included in
the BTC system.
• This is the reward for work associated with adding a new transaction block
to the existing transaction block chain for Bitcoin
– Because these nodes are using a lot of computational power (Hardware and
electricity) to come up with these proofs
• Moreover, succeeded miner also get to collect the transaction fees that
are specified in the transaction records
45. Bitcoin Generation (reward)
Whoever solved the hash can include their
transaction into new block (for reward)
Also collects all transactions fees inside of that block
46. Bitcoin Generation
• Totally 21,000,000 BTC
– Total number of BTC will be generated for reward (Maximum
number of BTC in BTC network)
– BTC system is public, so anyone knows how many BTC have
been generated
• 25 BTC reward
– Current BTC reward for solving new block (This was 50 at the
beginning)
• Transaction Fees
– After all BTC generated, reward will depends on the transaction
fees
47. Bitcoin Generation
• Reward size is cut in half every 210,000 blocks (4 years)
– Every 10 minutes there’s new block generated
– So 1 block * 6 (hour) * 24 * 365 * 4 = 210,240
• Every 2016 blocks proof of work is normalized (2
weeks)
– Estimated time: 10 min * 6 (hour) * 24 (day) * 14 = 2016
– When blocks are generated faster than 2 weeks, proof of
work becomes harder
– Otherwise it becomes easier (fewer miners)
48. Bitcoin Generation
• At around year 2140, all bitcoins will have
been generated
• BTC are fractional
– Smallest possible unit is: 0.0000 0001 BTC
(Satoshi)
– All other units
• Bits or μBTC – 0.000001
• mBTC - 0.001..
50. Is it slow? (Transaction)
• Bitcoin transactions are not slow, in fact it is
INSTANT! But confirmations take 10 minutes on
average (New block generation time)
• Confirmation is supposed to take care of double
spending problem
• If customer buys small stuff like coffee customer
doesn't have to wait at all. The merchant simply
takes the risk
51. How to Get Bitcoin?
• There are currently four methods of acquiring
Bitcoins:
1. Mining (Requires large investment)
2. Wiring in fiat currency to an BTC exchange
(www.coinbase.com)
3. Buying from an individual
4. Selling items for BTC
52. Where Do I Store Bitcoin?
• Bitcoins are stored in wallets
– Wallets is a randomly generated string of numbers and
consists of: private key and public key
• There are three different types of Wallets:
1. Online wallet service
• Create and remember passwords for our behalf (coinbase.com)
2. Local wallet or offline wallet
• Download and install on our computer (We need to download
all block chains on your computer ~ over 20GB)
3. Paper wallet
• Keys are generated offline and printed on a physical piece of
paper
54. BTC vs USD
• Currently there is 14,083,600 BTC generated
• 1 BTC = $234.54 USD ($221 USD 10 days ago)
• Market Cap: 234 * 14,083,600 ~ $3.3B Billion USD (3.1 10 days ago)
•
Price bubble
1 BTC ~ $1000 USD
55. Potential Outcome of BTC
• BTC will either succeed with the mainstream or fail
• If succeed:
– By 2025
• The estimated world GDP is expected to be around $71T in the
year 2025
• “If” BTC can establish a 0.1% Market Cap or $71B and 25% are
used for transactions, then market price of one Bitcoin would be
about.. ($14,947) (Old data from end of the 2013)
• Rule #1 of investing: (Because of “if”)
– Invest only what you can afford to lose!
• Bitcoin is still experimental, so its future cannot be
predicted by anyone.
56. Price
– Previous data is from 2013
• Current GDP US$74.31 trillion (from wikipedia)
• Market cap: 0.0044% of the current GDP
• 100.000 - 300.000 BTC are used for the transaction (every day) (0.0045% used for
the transaction) from 3.3B
– Saving (not using)
– When it becomes 0.1% and
– 25% of them used for the transaction
• 1 BTC ~ $15.000 USD
• Price depends on Market capacity
• And number of transaction used
• Value of the bank balance is set by supply and demand of the market
57. Fee per day
12 – 17 BTC is used for everyday25 BTC from reward
62. Price and Market Cap
BitCoin LiteCoin
1 vs USD
$234.50 USD ~1.4 USD ($1.42771)
Market Capacity
$3,299,521,813.80
(~$3.3B USD)
100%
$55,143,333.40
(~$55M USD)
1.67%
# of Transactions
106,955 4,505
63. Conclusion
• Bitcoin is decentralized cryptocurrency
• Transferred person to person
• No bank or government control
• Low transaction fees
• Bitcoin solves “double spend” problem through distributed network
– Proof of work
– Hash
• Open to anyone
– Public ledger
– Block chain
• Very difficult and expensive to hack
– Winning a lottery consecutive times in 10 minutes
• Transparent (open source)