david wong

Hey! I'm David, a security consultant at Cryptography Services, the crypto team of NCC Group . This is my blog about cryptography and security and other related topics that I find interesting.

Publishing my smart contract on the main ethereum network

posted 4 weeks ago

warning: as this is a proof of concept to see if 4chan could be implemented on the blockchain, some people might post shocking pictures or videos on there. At the time of the writing nothing "bad" has happened, but take precautions if you're planning to take a look at it :)

This is part II of Writing a DAPP for the Ethereum block chain I guess (where I previously said I would not publish this smart contract on the main network).

Pulling the entire Ethereum blockchain took me all afternoon. The thing is taking 29GB of disk space at the moment.

I sent ~20USD worth of ether (0.10 ether) from Coinbase to my real Mist wallet and prepared to see how much it would cost to deploy my smart contract. Surprisingly it was cheap! It cost me 0.007715952 ETHER which is ~2USD (around 1 million unit of gas at 0.008 ether per million gas) to deploy my contract to 0x470fb19D08c3d2eB8923A31d1408c393Dab09ccF an address computed out of my keypair and a nonce. I do not own its associated private key because I simply will never need it.

etherscan source code

To make sure the smart contract's code was properly open sourced on etherscan.io I had to put the source code there and provide the used compiler's version and the ABI encoded arguments to the controller. The ABI encoded arguments are just the 0-padded hexadecimal encoing of the arguments. I had two uint256 as arguments to my FiveMedium() constructor: the fee to post a thread and the fee to reply to a thread.


I decided to set the creation of a thread around 1$ and replying to a thread around 10 cents. It was then time to push the button and publish it.


And voila! You can access the DAPP on davidwong.fr/FiveMedium.

Note: the mandatory gas cost to post or reply on a thread seems to be around 0.30$. This has influenced me to lower down the contract fees to approach the gas fees.

Well done! You've reached the end of my post. Now you can leave me a comment :)