Jason Simeon Genge A code - What is Ethereum ?

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Jason Simeon Genge
Jason Simeon Genge https//www.slideshare.net/jaso
nsimeongenge1 2017
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The Blockchain

• In 2008, Bitcoin was launched as a peer-to-peer
  database that relied on a new data structure
  referred to as the blockchain.

• The blockchain consists of blocks, where each
  block holds a set of transactions and a
  reference to the previous block. This helped
  create a chain of all transactions that ever
  occurred.

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• This data structure is replicated across all
  participating nodes so that every participant is
  aware of the transactions without having to get
  them from a central authority.

Jason Simeon Genge
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Distributed Consensus

• In order to control how new blocks (with new
  transactions) are added to the chain, the design
  relies on a consensus mechanism which requires
  anyone (a node in the peer to peer network) who
  would like to nominate a new block (with new
  transactions it has gathered from its peers) to
  solve a puzzle that requires significant
  computations (computer processing power). The
  difficulty of this puzzle is dynamically
  adjusted such that it takes on average 10
  minutes for any one node to solve the puzzle. A
  process known as mining.
• Whenever a node solves the puzzle and create the
  new block (which includes new transactions that
  it has gathered from other peers around it), the
  node is rewarded with an amount of new Bitcoins
  which it can use to pay for the cost of solving
  the puzzle (computer equipment and electricity).

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ethereum
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Decentralization

• Given the architecture of the blockchain, the
  database continues to grow so long as nodes keep
  trying to nominate and verify new blocks
  regardless of nodes joining or leaving the
  network

• The fact that the entire database exists without
  depending on a single node, makes it very
  powerful and almost impossible to alter or
  destroy (the decentralized feature of the
  blockchain)

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• The integrity/validity of transactions in the
  block chain is ensured through the use of
  cryptographic techniques that make it efficient
  to verify if any invalid transactions have been
  added

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ethereum
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Beyond Bitcoin

• The architecture of the blockchain is very
  powerful as it enables decentralization while
  maintaining security. This has significant
  implications on the design of computer systems
  as it allows computer applications to be scalable
  and reduce the requirement for a large central
  infrastructure

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• While the first successful use of the blockchain
  database architecture was demonstrated on the
  Bitcoin network, many started exploring how they
  can utilize this design for other transactions
  beyond value transfer transactions which Bitcoin
  mainly handles

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ethereum
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Towards a Peer to Peer Computing Framework

• While, the design of the blockchain solved many
  issues when it comes to decentralizing and
  securing transactions. There was no easy way to
  specify logic that made use of that database for
  purposes beyond the transfer of value between
  accounts.
• The Ethereum project set out to design the
  required pieces to evolve the blockchain from a
  distributed transactional database to be part of
  a general purpose peer to peer computing
  framework.
• At the heart of ethereum is a virtual machine
  capable of executing instructions known as the
  Ethereum Virtual Machine (EVM), it allows the
  execution of programmed instructions stored
  within the blockchain

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The Blockchain of State and Transactions

• To introduce the ability to execute programs,
  the blockchain was modified such that each block
  not only contains the latest transactions but
  also the latest state of member programs (aka.,
  contracts).

• With every new block the state of contracts in
  the blockchain is updated per the processed
  transactions thereby taking the blockchain to a
  new state.

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• As a mean to ensure that provided instructions
  do not run forever, a constraint is built into
  the execution of every contract so that any
  party invoking a contract in a transaction is
  required to provide special tokens of monetary
  value that get consumed depending on the number
  of instructions and the storage used by the
  contract.

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Contracts as Accounts

• A contract has a permanent address on the
  blockchain which gets assigned when it is
  created. This permanent address is used to
  identify the contract.
• Every contract contains a balance of the basic
  monetary unit in the ethereum network referred
  to as ether.
• If a contract does not include any programmed
  instructions, it behaves as an account. It has an
  address and a balance. This account can
  receive/send ethers from/to other
  accounts/contracts.

Address Balance
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ethereum
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Contracts as Decentralized Executable Programs
Address Balance

• Ether is required to call a contract, this is
  done to ensure that infinite execution does not
  occur as the execution stops the moment the
  ether amount sent along with the call is
  consumed
• When a contract is called, a small amount of
  ether is required to be sent along with the call.
  This amount is eventually transferred to the
  node that gets to nominate the next block in the
  block chain. However, when a contract is called,
  an amount of ether can be directly transferred
  to that contract there by instituting a balance
  transfer like in the case of a payment
• When referring to the calling of a contract, it
  is in reference to invoking one of the methods
  in the programmed instructions which can be
  used to execute a certain action

Fields - - Methods - - Events - -
ethereum
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Contracts as Decentralized Executable Programs
Address Balance

• The execution of a method can modify the state
  of the contract by manipulating one or more of
  its fields
• A contract can also have set of events which are
  used to notify interested parties of the
  occurrence of certain events during the lifetime
  of the contract
• A contract lives forever on the blockchain once
  it is created unless, the original instructions
  made use of the suicide feature, a feature which
  destroys a contract and transfers its ether
  balance to another account

Fields - - Methods - - Events - -
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ethereum
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Messaging and File Sharing...

• In addition to the use of the ethereum virtual
  machine to execute contract logic. The ethereum
  project also introduced two additional protocols
  to provide peer to peer support for exchanging
  message as well exchanging static files

ethereum

• The peer to peer protocol used for exchanging
  message is named whisper and it provides a
  powerful distributed and private messaging
  capabilities with support for single cast,
  multicast and broadcast messages

• The peer to peer protocol used for exchanging
  static files is named swarm and it provides a
  new incentivized approach to distribute static
  content among peers and exchange them efficiently

swarm
whisper
Jason Simeon Genge
ethereum
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Decentralized Messaging

• Whisper provides a peer to peer protocol for
  exchanging short timed messages privately
• Whisper relies on a subject key (Topic) approach
  to deliver messages where messages are published
  using a hashed topic
• Messages can be encrypted with a specific key
  for privacy

whisper

• Indirectly supports broadcast, multicast and
  unicast

• Whisper is a high latency and low bandwidth
  messaging protocol
• Provides the ability to use masks/filters to
  narrow down topics of interest without giving
  away what topic is being sought

ethereum
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Incentivized File Transfer ...

• Leverages the underlying ethereum infrastructure
  through the use of a contracts and ethers to
  encourage cooperation among nodes
• Files are split into chunks which are stored in
  nodes in the network

• An accounting protocol is used by peers to keep
  track of chunks delivered and received and
  resulting micro-payments owed

swarm
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DEMO

• Assume we would like to create a smart door
  which opens up if given the right key.
• Adding a new user required two or more users to
  authenticate the transaction.

Jason Simeon Genge
ethereum
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ethereum
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Jason Simeon Genge