Published in Coinmonks·Oct 6, 2019Store data in Ethereum by logging to reduce gas costI propose a realistic solution to using Ethereum as a public ledger — Problems are gas cost and capacity We will face two problems with using Ethereum as a public ledger. The first one is the gas cost. Storing data to storage is the most expensive operation. (see SSTORE gas cost) The other one is capacity. …Ethereum3 min readEthereum3 min read
Published in Coinmonks·Aug 9, 2019IPFS Production ConfigurationNear future, our team will use IPFS for production service so I investigated lots about the configuration of it. I’m going to share my learned knowledge. 1. Preparation At first, export “IPFS_PATH”. export IPFS_PATH=/data/ipfsrep The IPFS repository is created to this path. The default path is your $HOME. …Ipfs4 min readIpfs4 min read
Apr 9, 2019Build HTTPS Support Load Balancer on AzureSetting ssl to Application Gateway using Ubuntu VM. I was so tired to achieve this, so I left my knowledge here. In Azure, there are 2 types of load balancer. One is Load Balancer and the other is Application Gateway. If you want to support https, only Application Gateway is…Ssl3 min readSsl3 min read
Published in LayerX·Mar 22, 2019Standard Sharing Economy Protocol for Smart ContractBlockchain is a good target to establish sharing economy, because the lessor and lessee can connected each other without any intermediates, like Uber or Aribnb. So, the lessor no longer be bothered by high margin cost. Origin Protocol is the pioneer of sharing economy on top of the Ethereum. …Ethereum4 min readEthereum4 min read
Published in LayerX·Feb 18, 2019How to reduce gas cost in SolidityGas efficiency tend to be low prioritized in most of the case. Since many projects pay attentions on security or cording readability. This time, I focus on gas cost saving. Then, I introduce 13 tips to reduce gas cost. Pre conditions The gas cost is calculated by Remix as compiler version is…Ethereum6 min readEthereum6 min read
Published in Coinmonks·Nov 23, 2018Express Quantstamp contracts as javascript — Audit completedQuantstamp is a smart contract security audit system by scalable and cost-effective way. I express Quantstamp contracts as Javascript for better understanding. Please refer to white paper or official blog for more information. GitHub: quantstamp-contracts-js Brief overview of Quantstamp The smart contract security is essential to prevent security incident like the DAO. Unfortunately, Current…Ethereum4 min readEthereum4 min read
Published in Coinmonks·Nov 2, 2018Express Plasma MVP as Javascript — Simple WithdrawalI express Plasma MVP as Javascript for a better understanding of my study. MVP is minimal viable plasma which is originally proposed by Vbuterin aiming to provide the basic security properties of Plasma in a very simplified way. Based on this proposal, OmiseGo implemented MVP for research aiming to use…Plasma7 min readPlasma7 min read
Published in Coinmonks·Oct 14, 2018Express uPort as javascript — Relay transaction to 3rd party Dapp.uPort is famous Ethereum project. In my opinion, uPort is the most successful self sovereign identity platform around blockchain. So I think understanding its strategy is helpful for our career. I express uPort contracts and IPFS or other objects as javascript. Then I simulate how work uPort is. Honestly, I…Blockchain4 min readBlockchain4 min read
Published in Coinmonks·Oct 12, 2018Express uPort as javascript — Set IPFS hash to Registry ContractuPort is famous Ethereum project. In my opinion, uPort is the most successful self sovereign identity platform around blockchain. So I think understanding its strategy is helpful for our career. I express uPort contracts and IPFS or other objects as javascript. Then I simulate how work uPort is. Honestly, I…Java Script5 min readJava Script5 min read
Published in Coinmonks·Oct 11, 2018Use ‘secp256r1’ to create JWT. Can not use 'secp256k1' which is famous for BitcoinWhen I studied about uPort which is famous for self sovereign identity platform on Ethereum, I struggled to create JWT(uPort achieve off-chain identification by JWT). So, I note my experience for future learner. Working sample code on Gist: jwt-secp256k1-secp256r1.js Error happen We can use ECDSA public/private key pair to sign JWT as…Java Script2 min readJava Script2 min read
