A cryptographic hash function is an algorithm that takes an arbitrary amount of data as input and produces the enciphered text of fixed size. Even a slight change in the input gives a completely different output.
Solidity provides the following cryptographic functions:
Ethereum uses Keccak for hashing which is similar but not the same as SHA_256. For proof of work, it uses a custom scheme called ethash which is designed to be ASIC-resistant.
Example: In the below example, a smart contract is created to take a string as input and give an 8 digit hash as an output.
// pragma version
pragma solidity ^0.6.6;
// Creating a contract
contract helloGeeks
{
// We want hash to be of 8 digits
// hence we store 10^8 which is
// used to extract first 8 digits
// later by Modulus
uint hashDigits = 8;
// Equivalent to 10^8 = 8
uint hashModulus = 10 ** hashDigits;
// Function to generate the hash value
function _generateRandom(string memory _str)
public view returns (uint)
{
// "packing" the string into bytes and
// then applying the hash function.
// This is then typecasted into uint.
uint random =
uint(keccak256(abi.encodePacked(_str)));
// Returning the generated hash value
return random % hashModulus;
}
}
Input:
GeeksForGeeks
Output:
Discussion (0)