Testing deployed Ethereum contracts with ESTIMATEGAS

This article is cross-posted at

Testing smart contracts live without spending gas

0xcert is publishing a series of tech papers in collaboration with various authors. The present article is a contribution by our advisor and the lead author of ERC-721 standard, William Entriken, and our lead blockchain engineer, Tadej Vengust. Live Testing Smart Contracts with ESTIMATEGASWritten by: William Entriken, Tadej Vengust In this article, we will introduce a technique that allows you to test any deployed contract in arbitrary ways, without spending gas. It works on Ethereum Mainnet, Wanchain, Ethereum Ropsten, Hyperledger Burrow, Proof of Authority Network, private chains, and every other network based on Ethereum Virtual Machine. This new technique was first shown with the ERC-721 Validator, and you can't do it with Truffle. You will want to learn this technique if: Your contract deployment …

Mac Software Worth Buying and Free Software Worth Getting

Mac Software Worth BuyingApple – Final Cut Pro Video editing Adobe – Lightroom Classic CC Photo cataloging and manipulation. "Classic" version prevents you from having your photos leaked if you work with photos that are important or sensitive. Microsoft – Office 2019 (not cloud) This is god-awful software that has click-throughs for OneDrive every time you try to save a file. Also the interface is painful with simple things like sorting in Excel hidden behind multiple clicks. Default fonts are stupid. But at least it isn't slow af like LibreOffice so you might as well buy it. 64 Characters — Telephone A SIP telephone client Panic — Transmit Because Apple isn't going to suddenly add remote file systems to the Finder if they haven't done it in the first 30 years Cultured Code — Things Tracks all your todos. This is not a multiplayer software, so this is your todos from your perspective only. There is much that could be improved but this i…

Storing Arbitrary-Length Data in a Merkle Tree

A hash tree, or a Merkle tree, is a data structure that allows you to take a lot of information and summarize it together in such a way that you (the "prover") can succinctly prove to somebody else (the "skeptic") that certain data is included.
Background Here is a typical Merkle-tree implementation:

Arrows represent inclusion in a hash. For example, A = hash(B, C). Hash() is customarily sha256().

Facts F1, F2, F3 and F4 are private. Or, a lighter requirement, there are just so many facts that you cannot be bothered to explain them to somebody else. You will publish root node A, the hash root. And this is proof to the world that this entire tree is encoded in A (if you choose to expose the tree). This rests on the worldwide assumption that hashes don't collide. If somebody is interested to confirm that F3 is included in A then you must share with them F4 and B so that they can recalculate A and confirm it matches the A you published.

Here is how that proof look…

Algorand white paper review

This article briefly reviews the Algorand technical paper as well as their white paper for investors. I don't know if the investor paper is public, so I wont link to it. But if you have seen you then you will know you have the right on if:

* In Chinese
* 1,208,476 bytes
* SHA256 d2fe315b4410dbf88e6054555d5b04c6edddef6c2ea6e1d1a12bbedf47b9eeff

Investor analysis:

* 写软件好容易。为什么找投资方?为什么不要直接写软件再找顾客?
* 复印软件好容易。他们的网络开通之后我们怎么知道别人不会复印他们?
* 区块链理论说的好清楚:一个网络不能同时安全、去中心化和有速度。他们发表了文件之后大家为什么还是相信这个理论?
* 第一句话开头是“目前没有一种加密货币。。。。。。”。已经好明显作家不懂区块链市场。为什么?应为加密货币是个应用但是以太坊是个平台。他们想开发一个系统不要开发一个应用。
* 他们的白纸没有提到spam或gas的问题。

Technical analysis:
You can see the weaknesses in these strong assumptions in the white paper.

• "[Adversaries] cannot interfere in any way with the messages exchanges among honest users. We assume that every propagated message reaches almost all honest users in a timely fashion." * "each small set of players associated to a step ... most probably has empty intersection with the…

Nontechnical: What is ERC-721?

Read time: 6 minutes. This post explains how ERC-721 works and does not require any prior knowledge of Ethereum or blockchain.

简体中文 -->通俗易懂的告诉你什么是erc-721/ (奇点财经翻译)

How does your phone connect to a web server?
Most of your time on computers/phones/technology is spent with a web browser accessing a web page. Most of the screens you see out in the world that display information are usually using a web page to show it, but they just hide the URL bar.

The flight arrivals screen -- it's just a web page
Think for a minute about how this ubiquitous technology works.

You. You are very busy and you are trying to access some information, maybe cat videos or sports scores or your family members' feedback on a photo you posted of your kid. Your phone, or whatever other device is in your hand, that acts on your behalf.The web server decides how it wants to reply to your request. Technology people, the ones that make your phone and the web servers, refer to y…

The Timeline of ERC-20 Approval

In Ethereum, the EIP process tracks standards, which are improvements to the state of affairs. Usually these standards affect interoperability of systems.

Either way, ERC-20, the token standard, is surely the most influential standard to date. I have researched the timeline of this standard, presenting below.

2015-11-19: Issue opened

2016-12-07: First mention of ERC20 in the EIP repository text

2017-04-24: The text of the issue is imported in the repository proper

2018-04-20: Made final

The Blockchain and Know Your Customer (KYC) Laws

Right now Web 3.0, "the blockchain", the decentralized web, etc. are making a lot of people rich. People will do anything to get a few Ether so they can spend it on a pictures of kitties or whatever. Here is the current best practice of how you can get Ether:

Send Western Union payment to somebody recommended by a company that is not in your legal jurisdiction to get Bitcoin, then using an exchange also not in your jurisdictionCreate an account in the United States which requires your social security number, your bank account website usernames/passwords (not a typo), and uncontrolled access to your computer's webcam
In other words, this is shady AF.

At one end of the respecting-regulation spectrum is Uber which says "we're not a taxi and we refuse to follow any taxi laws." But the Web 3.0 players are on the other end where they collect more information from you than any traditional bank.

The reason why is because banks are subject to "Anti Money Launder…