Bitcoin


A payment protocol

blockchain



    Distributed Timestamp Server

      Not a payment protocol

      define: payment protocol


      How money is
      • gained
      • held
      • spent
      • used

      transactions

      Transactions





      What information do we need:


    • Public key of recipient                   (address)
    • Reference to the previous transaction
    • Signature of owner
    • Real Transactions

       Transaction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

      scriptsig

       483045022100F3581E1972AE8AC7C7367A7A253BC1135223ADB9A468BB3A59233F45BC578380022059AF01CA17D00E41837A1D58E97AA31BAE584EDEC28D35BD96923690913BAE9A0141049C02BFC97EF236CE6D8FE5D94013C721E915982ACD2B12B65D9B7D59E20A842005F8FC4E02532E873D37B96F09D6D4511ADA8F14042F46614A4C70C0F14BEFF5

      Of the form 

      <signature><public-key>


      Scriptpubkey

      Hex:
      76 A9 
      14 1AA0CD1CBEA6E7458A7ABAD512A9D9EA1AFB225E88 AC
      OP_DUP OP_HASH160
      <ADDRESS>OP_EQUALVERIFY OP_CHECKSIG
      These are the instructions for how to spend the transaction!

      EXECUTION

      < signature> <pubkey> 
      OP_DUP 
      OP_HASH160 
      <address> 
      OP_EQUALVERIFY
      OP_CHECKSIG

      english

      Give me a signature and public key
      I'm going to duplicate the public key
      and use one to make an address
      I'm going to check this address against the one provided
      If they're identical, I'm going to verify the signature
      If that verifies, you can spend the money

      The stack

      Empty

      <signature>

      <signature> <pubkey>

      OP_DUP


      <signature> <pubkey>

      Input: Anything
      Output: Input repeated

      <signature> <pubkey> <pubkey>

      OP_HASH160


      <signature> <pubkey> <pubkey>

      Input: Public Key
      Output: Address

      <signature> <pubkey> <address>

      <signature> <pubkey> <address> <address>

      OP_EQUALVERIFY


      <signature> <pubkey> <address> <address>

      Input: 2 strings
      Output: nothing or mark-invalid

      <signature> <pubkey>

      OP_CHECKSIG


      <signature> <pubkey>

      Input: Signature and Public Key
      Output: 1 or 0

      1

      OVerview

      Input: < signature> <pubkey>
       
      Script:
      OP_DUP    OP_HASH160 
      <address> 
      OP_EQUALVERIFY
      OP_CHECKSIG

      Standard Transactions


      This is an example of a standard transaction


      They are able to be 'read' or 'understood' by your Bitcoin Client


      Conforms to a known template

      multisig txs (BIP 0011)

      ScriptPubKey:
      m {pubkey} ... {pubkey} n     OP_CHECKMULTISIG 
      ScriptSig:
      OP_0 {signature} ... {signature} 
      OP_CHECKMULTISIG Input:
      OP_0 followed by m signatures
      Output:
      1 or 0

      Pay-to-pubkey

      ScriptPubKey:
      {pubkey} OP_CHECKSIG 
      ScriptSig:
      {signature}
      OP_CHECKSIG Input:
      <signature> and <pubkey>
      Output:
      1 or 0

      pay-to-password

      ScriptPubKey:
      OP_SHA256 {hash} OP_EQUALVERIFY
      ScriptSig:
      {password}
      OP_SHA256 Input:
      <data>
      Output:
      <hashed data>

      CRAzy stuff

      Chain Trade:
      IF 2 {key A} {key B} 2 CHECKMULTISIGVERIFY ELSE {key B} CHECKSIGVERIFY SHA256 {hash A} EQUALVERIFY SHA256 {hash B} EQUALVERIFY ENDIF 
      Two options for evaluation:
      • 2 of 2 multisig transaction
      • 1 signature and 2 passwords

      What I didn't cover

      Lock time:
      Keeps a tx non-final until a specified time
      (cannot be included in a block)

      Sequence Number:
      Allows for tx replacement

      BONUS: PAY-TO-SCRIPT-HASH

      Your address IS the ScriptPubKey
      Example:
      ScriptPubKey: (2 of 3 multisig)
      52410491bba2510912a5bd37da1fb5b1673010e43d2c6d812c514e91bfa9f2eb129e1c183329db55bd868e209aac2fbc02cb33d98fe74bf23f0c235d6126b1d8334f864104865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac09ef122b1a986818a7cb624532f062c1d1f8722084861c5c3291ccffef4ec687441048d2455d2403e08708fc1f556002f1b6cd83f992d085097f9974ab08a28838f07896fbab08f39495e15fa6fad6edbfb1e754e35fa1c7844c41f322a1863d4621353ae
      OP_2 {pubkey}x3 OP_3 CHECKMULTISIG
      Resulting Address:

      3QJmV3qfvL9SuYo34YihAf3sRCW3qSinyC

      Bitcoin - Payment Protocol

      By Max Kaye

      Bitcoin - Payment Protocol

      Talk for BitcoinSYD 25/11/13

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