Tinycoin

What is it?

Tinycoin is a minimal implementation of Bitcoin in C++. It is not designed to be used as a Bitcoin node, but rather to learn how Proof of Work cryptocurrencies function and provide a small example project.

Building

Windows 11 with Visual Studio 2022 for build environment and vcpkg for library management is strongly suggested. The project depends on the following x64 and x86 static libraries:

• openssl
• boost
• fmt
• spdlog

Quick start

• Run a miner node

  $ tiny-sandbox.exe --port 9901 --node_type miner --wallet miner.dat
  
  [ 17:49:24 ] [ tc ] Generating new wallet miner.dat
  [ 17:49:26 ] [ tc ] Your address is 172eJPtmt5wMq71bnT1fS55FYLHw1syhWB
  [ 17:49:28 ] [ tc ] Load chain failed, starting from genesis
  

• Wait for a few blocks to go by

  [ 17:49:28 ] [ tc ] Start mining block 0881dfd39dbc50325850c3992b5c18ba8c30520a4c4fdce588fb899f53d82e44 with 0 fees
  [ 17:49:47 ] [ tc ] Block found => 19 s, 607 KH/s, 000000245f1ad9e00ba03836316fa2a896b79b08f8e0b3c32fac4da5225ba877, 2877728
  [ 17:49:47 ] [ tc ] Connecting block 000000245f1ad9e00ba03836316fa2a896b79b08f8e0b3c32fac4da5225ba877 to chain 0
  [ 17:49:47 ] [ tc ] Adding TxOutPoint 72a1142476ef4c9241545fc02ca6ed48a337fbfd24171127fd1bcbad0a6fc44e to UTXO map
  [ 17:49:47 ] [ tc ] Block accepted at height 1 with 1 txs
  [ 17:49:47 ] [ tc ] Saving chain with 2 blocks
  ...
  

• Run a wallet node

  $ tiny-sandbox.exe --port 9902 --node_type wallet --wallet miner.dat
  
  [ 17:49:48 ] [ tc ] Your address is 172eJPtmt5wMq71bnT1fS55FYLHw1syhW
  

• Generate an empty wallet

  $ address receiver.dat
  
  [ 17:50:57 ] [ tc ] Wallet receiver.dat belongs to address 16KHYopvjuY3mVLtEPHDLTzemWbPV6agoi
  

• Send coins from miner wallet to empty wallet

  $ send 16KHYopvjuY3mVLtEPHDLTzemWbPV6agoi 50000
  
  [ 17:51:23 ] [ tc ] Built transaction a5328f5688ff6b39de25af6a7bab840cc4e1156a26dabb10e2d01b12cbfa9eef with 100 coins/byte fee
  [ 17:51:23 ] [ tc ] Built transaction a5328f5688ff6b39de25af6a7bab840cc4e1156a26dabb10e2d01b12cbfa9eef, broadcasting
  

• Wait for transaction to get mined in a block

  ...
  [ 17:51:23 ] [ tc ] Recieved transaction a5328f5688ff6b39de25af6a7bab840cc4e1156a26dabb10e2d01b12cbfa9eef from peer 127.0.0.1:62256
  [ 17:51:23 ] [ tc ] Transaction a5328f5688ff6b39de25af6a7bab840cc4e1156a26dabb10e2d01b12cbfa9eef added to mempool
  ...
  [ 17:51:44 ] [ tc ] Added transaction a5328f5688ff6b39de25af6a7bab840cc4e1156a26dabb10e2d01b12cbfa9eef to block 1f4fb281eb44989700c3e9aba535191e684657c06911e0f0aed1795f967c88df
  [ 17:51:44 ] [ tc ] Start mining block ff02250fc300e1b53c40528e9fba7f89df34e7f6cb4a896e8fde84872e23461b with 30000 fees
  [ 17:52:55 ] [ tc ] Block found => 71 s, 699 KH/s, 000000275c6044cf9f39de8710a1bdf799043d2d634dbcd1584d3591168b5123, 4611686018440151883
  [ 17:52:55 ] [ tc ] Connecting block 000000275c6044cf9f39de8710a1bdf799043d2d634dbcd1584d3591168b5123 to chain 0
  [ 17:52:55 ] [ tc ] Adding TxOutPoint bc1d12d2105f55527f359721e5b03e14a094037a36cbda70402a3543d939d3f4 to UTXO map
  [ 17:52:55 ] [ tc ] Adding TxOutPoint a5328f5688ff6b39de25af6a7bab840cc4e1156a26dabb10e2d01b12cbfa9eef to UTXO map
  [ 17:52:55 ] [ tc ] Adding TxOutPoint a5328f5688ff6b39de25af6a7bab840cc4e1156a26dabb10e2d01b12cbfa9eef to UTXO map
  [ 17:52:55 ] [ tc ] Block accepted at height 5 with 2 txs
  [ 17:52:55 ] [ tc ] Saving chain with 6 blocks
  ...
  

• Check balance of receiver wallet

  $ balance 16KHYopvjuY3mVLtEPHDLTzemWbPV6agoi
  
  [ 17:53:11 ] [ tc ] Address 16KHYopvjuY3mVLtEPHDLTzemWbPV6agoi holds 50000 coins
  

TODO

• Replace by fee
• Transaction locking
• Orphan blocks
• Chainwork
• Peer discovery
• Full node