Installation

We need to install two command-line tools:

• geth - the Ethereum client built using the Go language
• solc - the Solidity compiler

> sudo apt-get install software-properties-common
> sudo add-apt-repository -y ppa:ethereum/ethereum
> sudo apt-get update
> sudo apt-get install ethereum
> sudo apt-get install solc

Create some accounts

We probably want to create a number of accounts

• first account to receive the benefits of mining activity - we'll call this user "theminer"
• second account who is the sponsored runner - "therunner"
• third account who pledges donations to the campaign - "thesponsor"
• fourth account who benefits from the contract - "thebenefactor"

Accounts are created from the command line by using the geth account new command and entering a password (twice):

> geth account new
Your new account is locked with a password. Please give a password. Do not forget this password.
Passphrase: 
Repeat passphrase: 
Address: {4bdebee7a217d04e86ab67be5b6e108148b1fc8e}

Repeat this process for two more accounts. We can then list our accounts with geth account list:

> geth account list
Account #0: {4bdebee7a217d04e86ab67be5b6e108148b1fc8e}
Account #1: {458305055882d53663b41a00eebd0b657469843f}
Account #2: {225905462cf12404757852c01edfd2ec0bf0dbe9}
Account #3: {63de8807ac0bd63be460be0de250749c4df1dcb0}

The Genesis block

The first block in a blockchain is called the "Genesis Block". We create a file called "genesis.json" containing:

{
    "nonce": "0x0000000000000042",     
    "timestamp": "0x0",
    "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "extraData": "0x0",     
    "gasLimit": "0x8000000",     
    "difficulty": "0x400",
    "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "coinbase": "0x3333333333333333333333333333333333333333",     
    "alloc": {     }
}

Then we can initialise our blockchain with

> geth --nodiscover --maxpeers 0 init genesis.json
I0413 16:31:32.885748 ethdb/database.go:82] Alloted 16MB cache and 16 file handles to /home/gbird/.ethereum/chaindata
I0413 16:31:32.892712 cmd/geth/main.go:333] successfully wrote genesis block and/or chain rule set: 6650a0ac6c5e805475e7ca48eae5df0e32a2147a154bb2222731c770ddb5c158

N.B older geth versions use geth --nodiscover --maxpeers 0 --genesis genesis.json

Mining

We need mining for two reasons

• to generate some wealth
• mining is used to verify transactions before adding to the blockchain, so this executes our Solidity code

To start geth so that it starts mining we can use the command:

geth --rpc --rpcport 8000 --rpccorsdomain '"*"' --mine --minerthreads 1 --maxpeers 0 --nodiscover --networkid 3301 console

Geth should startup and then spend the next 15 minutes or so generating the DAG. This delay only occurs on your first run.

In other consoles on the same server, we can run geth attach to interact with the contract.