Questions tagged [keccak]

keccak is a cryptographic family which is used in ethereum and nowerdays provides the standards for sha-3

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2answers
983 views

How is the keccak256(a, b) function implemented?

I need to understand how keccak256(a, b) is implemented and how it differs from keccak256(a || b). Is the content padded? I need this because I do not want to allow for vulnerabilities where a user ...
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2answers
181 views

Common use cases for hashing functions? [closed]

I'm developing my first dapp with solidity and I was wondering in which cases should I use hashing functions like keccak. I know how they work but it is not clear to me when should I use them and to ...
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0answers
81 views

are all bits of a keccak256 'uniformly distributed'? [closed]

If I have a truly random data source, and generate keccak256 hashes of the numbers of this source: N1 = keccak256(rnd1) N2 = keccak256(rnd2) N3 = keccak256(rnd3) ... are all 256 bits of the ...
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1answer
365 views

Keccak256 collision in function’s prototype

I was reading the github version of the upcoming book Mastering Ethereum, where the author defines the function selector as The first 4 bytes of the Keccak256 hash of the function’s prototype. This ...
0
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1answer
252 views

How to get EVENT name from event signature hash?

I fount that some developers can get event_signature_hash for a event's name MyEvent(uint256) by using bellow code: event_signature_hash = w3.sha3(text='MyEvent(uint256)').hex() But vice versa, I ...
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1answer
1k views

bytes4(keccak256(“function(uint256)”)) vs. (abi.encodeWithSignature(“buyItem(uint256)”)

What is the (a) technical difference between and (b) practical difference between these, i.e., when do you use one or the other: bool result = address(contract).call.value(10)(bytes4(keccak256("...
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1answer
1k views

How to typecast keccak256 function with multiple arguments to uint256?

solidity ^0.4.19 (works) uint256 randNonce++; return uint256(keccak256(msg.sender, randNonce, now)) solidity ^0.4.24 (throws) uint256 randNonce++; return uint256(keccak256(abi.encodePacked(msg....
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1answer
455 views

Why does keccak256() return bytes32 instead of uint256 in Solidity?

A hashing function outputs an integer that is 256 bits long... so why not store it as such?
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1answer
1k views

From golang sha3 to solidity sha3

Trying to match "golang.org/x/crypto/sha3" lib with solidity sha3() is giving me a hard time. Its been discussed in here, but I somehow cant apply it in go. How do I handle a big.Int type s.t i get ...
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2answers
189 views

Why public keys are not used directly as account addresses? [duplicate]

I understand that addresses are hashes of the public keys. But why? What is the rationale behind this design decision? And why 160 bits? Why not just use the hash directly? Is 160-bit guaranteed ...
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0answers
19 views

How to use bytes to get the same hashed output [duplicate]

I previously asked a question here: link to previous question. Found out the answer is to use string instead of bytes here: pragma solidity ^0.4.18; contract C { bytes32 public temp; ...
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2answers
2k views

solidity ..which hashing algorithm to use?

I have tried using many hashing algorithms but there output in solidity doesn't match with the one given in online converters. Here is my program:- pragma solidity ^0.4.18; contract C { bytes32 ...
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1answer
292 views

Keccak256 of msg.sender and timestamp: what's the likelihood of an output coincidence?

Let's think about this code: function publishEtherBox (bytes32 _label, string _ownerUrl, uint _lifespan) external onlyWhenRunning() payable { require(ownerToEtherBoxes[msg.sender].length < ...
0
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1answer
447 views

Compare byte32 Keccak256 to the same Keccak256 stored in a byte32 array

I want my function to be able to accept an array of Hashed secrets as a parameter and since solidity doesn't allow for strings, I had to use a byte32[]. The string parameter is an intake for the user'...
3
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1answer
4k views

SOLIDITY: How to get a bytes32 keccak256 hash of an address and 2 uint256 variables

I would like to know how to get a bytes32 keccak256 hash of an address and 2 uint256 variables. I want something that will look like this. But from the remix IDE errors, I need to make the the 3 ...
2
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1answer
93 views

Incorrect result for hash calculation

According to this link, [https://github.com/ethereum/EIPs/blob/master/EIPS/eip-155.md][1]. The "signing data" becomes: ...
6
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1answer
1k views

Compare structs and arrays with keccak256 in order to save gas

Just working on a solidity code last day, I figured out that apart of comparing bytes, strings etc... The Keccak256 will be the perfect solution for comparing large arrays or big structs. Because as ...
4
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1answer
590 views

How to derive the storage key of mapping to an account?

I am trying to derive changes of account storage by mapping accounts (here, the accounts represent the key address in the ERC20 balances mapping mapping(address => uint256)) to their corresponding ...
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2answers
2k views

does keccak256 and sha3 reproduce the same hash ?

I have this solidity method: function hashData(bytes32 data) public constant returns (bytes32) { var hash = keccak256(data, msg.sender); return hash; } for a data = "0x707974686f6e62" and ...
2
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2answers
744 views

Solidity: How to verify Keccak-256 value?

I want to pass a Keccak-256 hashed value from the front-end, say a string "experiment". I store the value in Solidity, and, when passing the same value for the second time, a Solidity function needs ...
1
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1answer
582 views

how to hash an array of address?

I want to hash a given array of address (using keccak256) into a single variable byte32. for example: function hashOfArray( address [] list) public constant returns (byte32) { var hash = ... ...
0
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1answer
348 views

how can I return a hash value using keccak256?

I have this solidity function below. It is supposed to return the hash of a given data, but instead I get this: 0x function hashData (bytes32 data) public constant returns (bytes32) { var hash ...
3
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1answer
816 views

Ethereum address genеration and keccаk256

I'm trying to generate eth address on PHP. Having issue with keccak256. I'm using this class: https://github.com/kornrunner/php-keccak It works good, I checked many times on https://emn178.github.io/...
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1answer
355 views

Elliptic Key Crytography(ECC) for generating Private & Public Key

I want to generate Public-Private Key pair using ECC and then import them to Ethereum for creating an account through Geth. I am working on a Windows machine. What are the steps I should follow for ...
1
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1answer
184 views

Handling keccak collisions in decoupled storage pattern

The decoupled storage pattern (https://blog.colony.io/writing-upgradeable-contracts-in-solidity-6743f0eecc88) uses a hash function (keccak) to turn arbitrary length values into 32 byte keys for the ...
2
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1answer
152 views

Understanding Low-Level Interface to Logs

This question is about Low-Level Interface to Logs, Solidity Documentation. In given examples we are able to emit event normally: pragma solidity ^0.4.0; contract ClientReceipt { event Deposit( ...
10
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1answer
170 views

Is it dangerous to name my function ccccvKygDv?

For those keeping track at home, the function hash of a function named ccccvKygDv() is 0xffffffff, the same as a null address. pragma solidity ^0.4.0; contract NullFunction { function ccccvKygDv()...
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2answers
859 views

Web3js and keccak different values

In solidity there is the keccak256 function which hashes its arguments. I use the keccak256 to compute and use the result to check if some entries exist in my array. I want to compute the same value ...
0
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1answer
562 views

sha512 in Solidity or assembly, does it exist? [duplicate]

Is it possible to do sha512 within a smart contract? Or, not?
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2answers
196 views

What is insecure about generating a random number with keccak256?

Just read that generating random a random number via keccak256 is insecure. What is insecure about it and what are the implications of insecurity?
6
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1answer
907 views

Why doesn't my private key's public key generate the correct public address?

Private Key: 9ccbcabf23e271183dbed503b43277f4c6eee9ac918cd6cda75ebb73ceb35c7d Corresponding Public Address: 0xa73Fb234B1773ed7b115D18A1f0a15579bA2C1e1 (check for yourself on MyCrypto, for example) ...
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2answers
638 views

Why doesn't my verification of a signed message signature work in PHP?

I am attempting to verify a signed message in PHP. To be clear, I am not looking to interface with JSON-RPC or any external service, which I both a) know works and b) successfully verifies the ...
0
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1answer
908 views

Problem with sha3.keccak_256() update method in Python

I made a simple SHA3 Python script to generate Ethereum addresses and priv/pub keys. After that I sent some ETH to those addresses but then found out that priv keys do not correspond to the addresses ...
0
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1answer
2k views

How to generate keccak256(STRING,INTEGER) from Javascript?

In my solidity code I use bytes32 generated by keccak256("STRING_VALUE',INTEGER) to store values in the map. One of the sample values that get generated is ...
0
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1answer
232 views

Solidity keccak256(“contract.storage.initialised”)

Hi I was searching on upgradeable/upgradable contracts, then I found this Rocket Pool by David Rugendyke https://gist.github.com/darcius/6e8fa4faa6d9139f3950b6f1d9e96038 /// @dev Only allow access ...
0
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1answer
458 views

Keccak hash of null values, result in different hashes for different types

I was testing the hash value of null values for different types and I'm curious how it generates different results for different types. Here are the results. String = ...
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0answers
411 views

keccak256 returns 0x000000000000000

I am using the keccak256 hashing algo to retrieve a message for a signature however I am getting the return value above. Here is the code: function adminAuthorizedSwap(string price, string quantity, ...
2
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2answers
565 views

Which sha3 output is the correct one?

Im trying to rewrite the all ethereum address creation and Tx creation in PHP and Im almost there. I have implemented a sha3 but now Im confused on if its giving me the correct output because it ...
1
vote
1answer
234 views

Correctly address Smart Contract storage address using web3js 1.0.0 library functions

A short while ago, I found a fantastic Medium article explaining Smart Contract storage. The examples in this article have helped me to understand how to read a Smart Contract's storage values from ...
2
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1answer
101 views

Fair, barely malleable CSPRNG that can still be deterministic?

Just for fun, I wanted to start off making a test contract that generates ERC-20 tokens based off of prime length when in binary representation. I decided to use Rabin-Miller for the primality test, ...
5
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2answers
3k views

Python and Solidity keccak256 function gives different results

I am working on implementing a smart contract application in which, on and off chain calculations will exist. I will have to calculate the Hash Function of multiple integers with Python and Solidity. ...
5
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1answer
1k views

Distribution of KECCAK-256 hash values

Are values hashed using KECCAK - 256 uniformly distributed? If I use a KECCAK - 256 hash and then convert it to a number in a range 0 - N using the modulo operation, would the probability of obtaining ...
14
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2answers
11k 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 ...
8
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5answers
7k views

How to keccak256 multiple types in web3js to match Solidity keccak256?

if I keccak256(string1, address1) in Solidity, and then use web3.sha3(string1, address1) in web3.js, I get different results, even though when I do both with only string1 as a single argument, they ...
7
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1answer
3k views

Sign raw transaction offline with C++ on arduino

I'm exploring the IoT side of the EVM. I've programmed Arduinos and ESP8266s to interact with a Geth JSON RPC. I'm trying to be minimalistic and avoid NodeJS on the Geth JSON server side. Currently ...
3
votes
1answer
889 views

Correct way to concatenate hashes for merkle tree

I'm using Richard Moore's ethers.js to create hashes of documents that will eventually be stored on the EVM. To create a merkle tree with many documents I'll need to hash together hashes. What's the ...
3
votes
1answer
762 views

Python keccak256 hash of uint8 array not matching solidity hash?

I have a function in a smart contract: function getNumberHash(uint8[] _numbers) constant public returns (bytes32) { return keccak256(_numbers); } When I pass [1,2,3,4,5] as the argument it ...
5
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2answers
3k views

Generate ethereum address in C#

I'm following the instructions here to generate a valid ethereum address from scratch. I'm using BouncyCastle's secp256k1 to do the privkey --> pubkey, but I don't know where to get a proper ...
0
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2answers
127 views

How to limit function access to certain frontend?

I've a function in my smartcontract, that pays out ETH to the sender. However it sgould be only callable from registered users on my website, regardless of their ETH-address. I already tried to send ...
6
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4answers
2k views

keccak3 in SOLIDITY and in WEB3 different hashes for an address type field

How can I get the same resulting hash from Keccak-256 ()in solidity and web3.sha3() in web3? IN solidity using keccak256( address ) and using web3.sha3 ( address ) gives different results. In web3 ...