Nchinda Nchinda
MIT grad, ethereum developer, bitcoin user
MedRec
chmod for medical records
Nchinda Nchinda
@Firescar96
Researcher in Viral Communications
https://slides.com/firescar96/medrec-45
Hashing
Public Key Cryptography
Diffie-Hellman
Signing
Encryption
Merkle Trees
zkSnarks?
On Distributed Communication Networks - Paul Baran
Bitcoin and the Blockchain
Strengths
- it works. today. right now.
- global reach
- objective inference
- inexpensive and swift
- irreversible transactions
- consensus and security
- psuedonymous
A cypherpunk is an activist who uses software, protocol, and most importantly cryptography to invoke social and political change.
https://bitcoin.org/bitcoin.pdf
- it works. today. right now.
- global reach
- objective inference
- inexpensive and swift
- irreversible transactions
- consensus and security
- psuedonymous
What's the Blockchain
- it works. today. right now.
- global reach
- objective inference
- inexpensive and swift
- irreversible transactions
- consensus and security
- psuedonymous
Consensus
PoW, PoS, PoA
What is mining?
It's like Sudoku
-
No central banks
-
No physical form
-
No government backing
-
Anyone can participate
-
No formal identification
Proof of Work
Hard to Solve, Easy to Verify
How hard can it be?
-
Current Bitcoin Difficulty (1011 different possibilities)
-
The number of bits on a computer hard disk (typically about 1013, 500-1000 GB)
-
The number of cells in the human body (more than 1014)
-
The number of neuronal connections in the human brain (estimated at 1014)
-
Maximum Bitcoin Difficulty (1077 different possibilities)
-
The estimated number of atoms in the observable Universe (1080)
-
The lower bound on the game-tree complexity of chess (estimated at around 10120)
- it works. today. right now.
- global reach
- objective inference
- inexpensive and swift
- irreversible transactions
- consensus and security
- psuedonymous
But...what is the blockchain?
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Alice -> Bob; 1 BTC; .0001 fee
Alice -> Charlie; 1 BTC; .0001 fee
Dan -> Alice; 1 BTC; .0004 fee
Reward: 12.5BTC
header
Alice -> Bob; 1 BTC; .0001 fee
Alice -> Charlie; 1 BTC; .0001 fee
Dan -> Alice; 1 BTC; .0004 fee
Reward: 12.5BTC
header
Alice -> Bob; 1 BTC; .0001 fee
Alice -> Charlie; 1 BTC; .0001 fee
Dan -> Alice; 1 BTC; .0004 fee
Reward: 12.5BTC
header
...
...
...
Reward: 12.5BTC
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...
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Reward: 12.5BTC
demo
Wallets do not hold your bitcoin
- it works. today. right now.
- global reach
- objective inference
- inexpensive and swift
- irreversible transactions
- consensus and security
- psuedonymous
Pseudonymity
Almost anonymous
- it works. today. right now.
- global reach
- objective inference
- inexpensive and swift
- irreversible transactions
- consensus and security
- psuedonymous
But Bitcoin is just a distraction from the blockchain...
Nyet.
What if we put code...on the blockchain
Types
- boolean
- true or false
- int and uint
- represent 256 bit signed and unsigned numbers respectively
- address
- holds a 20 byte ethereum address
- bytes1 - bytes32
- fixed size byte array
-
struct
- fixed size byte array
-
enum
- fixed size byte array
Contract Structure
pragma solidity ^0.4.0;
contract SimpleStorage {
uint storedData;
function SimpleStorage() {
// ...
}
function bid() payable { // Function
// ...
}
}
}
Special Operations
- msg.sender
- the ethereum address that directly called the contract
- msg.value
- value of the calling transaction
- block.number
- current blocknumber
- sha256 and sha3
- hash functions
-
selfdestruct(<address>)
- kill self and send money to an address
-
wei, finney, szabo, ether
- currency denominations
Contract walkthrough
Applications
Ethereum Blockchain
go-ethereum
ganache-cli
parity
MedRec
Web3
MedRec
overview of contracts
MedRec in 45 minutes
By Nchinda Nchinda
