Hashing

Overview

This page contains recommendations for choosing a hashing algorithm.

General

If you need to hash passwords see the the Authentication: Password Storage page.
For other data, use a hashing algorithm from the SHA-2 or SHA-3 family.
Do not use vulnerable hashing algorithms from the list below. You can find examples of collision attacks at https://github.com/corkami/collisions.

Vulnerable hash algorithms

MD4
MD5
SHA-0
SHA-1
HAVAL-128
PANAMA
RIPEMD

Hashing implementation

Use the implementation of hash algorithms from the crypto package, such as crypto/sha256 or crypto/sha512. You can find the whole list at https://pkg.go.dev/crypto#Hash

package main

import (
    "crypto/sha256"
    "fmt"
)

func main() {
    p := []byte("random string for hashing")
    hash := sha256.New()
    fmt.Printf("%x\n", hash.Sum(p))
}

Use the java.security.MessageDigest class for hashing implementation. MessageDigest is not thread-safe. Use a new instance for every thread.

import java.security.MessageDigest;
import java.nio.charset.StandardCharsets;
import java.security.NoSuchAlgorithmException;

public static String sha256Hash(String data) throws NoSuchAlgorithmException {
    MessageDigest digest = MessageDigest.getInstance("SHA-256");
    byte[] encodedHash = digest.digest(data.getBytes(StandardCharsets.UTF_8));
    return toHex(encodedHash)
}

public static String sha3256Hash(String data) throws NoSuchAlgorithmException {
    MessageDigest digest = MessageDigest.getInstance("SHA3-256");
    byte[] encodedHash = digest.digest(data.getBytes(StandardCharsets.UTF_8));
    return toHex(encodedHash)
}

private static String toHex(byte[] byteArray) {
    String hex = "";
    for (byte i : byteArray) {
        hex += String.format("%02x", i);
    }
    return hex;
}

Use the crypto package for hashing implementation. The list of supported algorithms is dependent on the available algorithms supported by the version of OpenSSL on the platform. Use openssl list -digest-algorithms to display the available digest algorithms.

const { createHash } = await import('node:crypto');

async function sha256_digest(data) {
    const hash = createHash('sha256');
    hash.update(data);
    return hash.digest('hex');
}

Use the hashlib package for hashing implementation. You can find the list of available algorithms here.

import hashlib

def sha256_digest(data: str) -> str:
    encoded_data = data.encode('utf-8')
    hash = hashlib.sha256(encoded_data)
    return hash.hexdigest()

def sha3_256_digest(data: str) -> str:
    encoded_data = data.encode('utf-8')
    hash = hashlib.sha3_256(encoded_data)
    return hash.hexdigest()

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Overview

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Hashing implementation