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Week 11 - Coggle Diagram

- - - - essentially a public ledger made up of blocks containing all previous transactions
    - - use a variety of bitcoin objects to search for
        
        block hash
        
        bitcoin address
        
        block height
        
        transaction hash
      - blockchain.com
        
        simple interface
        
        great documentation on its Public API
        
        powerful API
    - - hash of the block that came before this block
    - - merkle root
        
        def: hash of all the hashes of all the transactions that are part of a block in a blockchain networ
        
        SHA-256 hash of the previous block stored in the header effectively creates a linked list of blocks
      - contains
        
        more data than just an array of tx
        
        header followed by array of tx* stored in block
      - first genesis block
        
        created in 2009
        
        released first 50BTC on the market
      - Time value
        
        refers to unix time that the block was verfied
  - - - Bitcoin wallet that has forensic implications
      - wallet +mixer hybrid and implements a modified version of coinJoin
      - possession is not itself an indicator of guilt but warrants further examination
    - - what are they
        
        equivalent to mailing addresses
        
        at least one addr to send and one addr to receive
        
        Bitcoins all exist in the blockchain, trading means transferring bitcoins in the ledger to another address in the ledger
      - making keys
        
        scalar multiplication is 1 way calc
        
        public key is converted into an address
      - Generator
        
        process invovling
        
        i25 byte scirpt value
        
        remove first 3 bytes and last two bytes
        
        run remaining 20 bytes through series of hashes
        
        prepend network id to arrive at actual address
      - How to get one
      - while requesting/sending bitcoin transaction, user will specify address to be used
      - associated to Bitcoins and not the wallet
      - associated to a pair of mathematically linked private and public key
        
        the address's public key is used to confirm the signature and valid tx
        
        private key used to sign tx as a digital signature
        
        public key is a 256 biy x and y values representing a specific point on Secp256k1 y^2=x^3+7
        
        public key is the result of scalar multiplication of private key +base point
        
        additional prefix is added to the public key
  - - - software signs tx with sender's priv key and broadcasts tx to network
    - - two sections for input and output
      - input and output count field
        
        number of addresses involved
  - - - sha-block 256 with certain number of preceding 0's
      - majority of 10mins is spent in trying to find such a hash
      - more users--> inc numer of preceding 0's --> inc difficultly of calculation
      - after every 2016 blocks a system automatically adjusts difficulty of hash
    - - correct nonce is broadcasted to network
        
        each node tries advertised nonce
        
        if majority agree then the block, all of its tx, is added to chain
        
        otherwise block is orphan
  - - - Miners speed(in GigaHashes/s)
        
        alternatives ASICs + FPGAs
        
        greater hashing rate better chance of finding the nonce
      - contribute their computing power to verify tx
    - - release new bitcoins to market
      - verify and add blocks to blockchain
    - - solo
      - pool members
        
        Pool mining
        
        odds of finding the nonce are higher, but the reward is plit among members based on each individual's contributed compuattion power
        
        as more coins are mined reward decreases
    - - is rewarded with bitcoins to the user that calculated the correct hash
      - reward halving of coinbase.. geometric sequence
        
        current 12.5
  - - - getdata
        
        contains a matching payload checsum to its parent inv and tx hash
        
        getdata mesasge= acknowledgement of a tx from the host to the node
      - tx
      - inv
        
        first sign of a tx
        
        advertising knowledge of tx(type 1 tx hash) and a block type 2
      - these occur after a tx with an intervening mesasge
      - have well defined packet structure
- - - - not controlled by one entity
    - - involves in asymmetric encryption and digital signature
  - - - pesudo-anonymous
      - peer to peer
      - decentralized
        
        digital currency
    - - helps securing the network and creation of a new block/chain
      - circumvent the financial institution's trust based model
    - - with computing power of certain users on the network
        
        makes cryptocurrency attarctive
        
        harder to be accepted by gov as it is out of their hands
    - - money laundering
      - nefarious deeds
      - why is Bitcoin ideal for illegal purposes
        
        its digital cash: ideal to purchase illicit goods online
        
        considered as opportunity to make money
        
        offers mixers: enables user to exchange with others
    - - signed tx protecting buyers
      - ability to exchange internationally
      - double spending protection for sellers
        
        in a centralized model trusted 3rd part verifies that money has not already been spent before allowing a tx
- - - - tracking app utilization over prefetch and userassit artefacts
      - historical activity
      - when it was running
      - how long the app was running
      - tx is stored in debug log