Linked Questions

260 votes
9 answers
195k views

What is meant by the term "gas"?

An Ethereum application that I want to use talks about needing "gas" to run. What is gas, and where do I get it?
Jeff Coleman's user avatar
  • 22.1k
33 votes
7 answers
49k views

how to compare strings in solidity?

pragma solidity ^0.4.11; contract test2 { address creater; string username; string password; function testusernamepassword(string username,string password) returns (bool) { ...
Deepak Baberwal's user avatar
56 votes
4 answers
19k views

Why don't Ethereum addresses have checksums?

A checksum, similar to its use in Bitcoin addresses, can primarily prevent mistyped or invalid addresses from being used, before a transaction with an invalid address is constructed. Why don't ...
eth's user avatar
  • 86k
27 votes
2 answers
10k views

Why aren't Solidity sha3 hashes not matching what other sha3 libraries produce?

Solidity has a function named sha3 and I tested it with an empty string input. It is not matching what other sha3 libraries produce. I see contracts written by others using the same sha3 function ...
eth's user avatar
  • 86k
32 votes
2 answers
25k views

Difference between keccak256 and sha3

I have been reviewing keccak256 implementation and sha3-256 that follows the FIPS standard. The sponge function is taking a while to set in, but I have noticed a difference in implementation : I ...
user2163865's user avatar
30 votes
1 answer
14k views

How can I verify a cryptographic signature that was produced by an Ethereum address key pair

If I have a cryptographic signature from an Ethereum address key pair, how can I verify that signature?
Piper Merriam's user avatar
28 votes
1 answer
11k views

What is the cheapest hash function available in solidity?

AFAIK there are 3 hash functions to choose from in solidity (sha3, sha256, and ripemd). sha3 is native while the others use precompiled contracts. Which one of these is cheapest (in terms of gas)?
Akhil F's user avatar
  • 1,928
14 votes
1 answer
2k views

At any given time, how many nodes is my node connected to? As the number of nodes in the network increases, will communication between them be faster?

I have been reading through the DEVp2p documentation and cannot seem to wrap my head around some aspects of the network. Specifically, how many nodes is my node connected to? Does this number change ...
user avatar
5 votes
2 answers
1k views

Are addresses hashes of public keys, or are they compressed public keys?

I understand that in Bitcoin, addresses are hashed public keys. However, I've also heard that compressed public keys are just as short as hashes while maintaining their 1:1 relationship. Does ...
Akhil F's user avatar
  • 1,928
3 votes
1 answer
6k views

Does Ethereum use Ethash or KECCAK-256 (an alias to SHA3) as hash function?

Ethdoccs says that the PoW algorithm Ethereum is using is Ethash. While I was searching around for information about Ethash, I ran across this post, which indicates KECCAK is the one. So what is ...
diidoobiib's user avatar
6 votes
1 answer
3k views

What is the computing power of the Ethereum network in FLOPS?

The aproximate computing power of current Bitcoin network in terms of FLOPS (FP32) has been estimated at about ~80,000 exaFLOPS and being aware of the limits of the analogy because of the widespread ...
ofou's user avatar
  • 11
2 votes
1 answer
3k views

Is Ethereum's mining algorithm vulnerable to ASICBOOST?

Bitcoin's hashing algorithm uses a multi-step hashing function. Some miners have used a technique referred to as ASICBOOST to exploit this. I'm unclear on the specifics, but it has something to do ...
Akhil F's user avatar
  • 1,928
9 votes
1 answer
579 views

Are there any plans to switch Ethereum's primary hash algorithm from Keccak-256 to SHA3?

The Ethereum project was started before the SHA3 standard was finalised, and currently uses an earlier version of Keccak-256 which does not precisely match the FIPS-202 standard for SHA. Are there ...
Jeff Coleman's user avatar
  • 22.1k
0 votes
1 answer
671 views

What is the return of uint(keccak256(_str));?

I'm doing the chapter 1 of the crypto zombies course. uint id = zombies.push(Zombie(_name, _dna)) - 1; NewZombie(id, _name, _dna); } function _generateRandomDna(string _str) ...
disqid's user avatar
  • 13
1 vote
1 answer
221 views

Is it cheaper overall to store a keccak hash or to store a ripemd(keccak) hash?

As titled. I'm learning to build a DApp and I'm wondering if it's worth it to add the extra RIPEMD layer over keccak for a shorter hash to reduce storage costs.
bishopqpalzm's user avatar