Hash Identifier

function identifyHash(hex) {
  const len = hex.length
  const isHex = /^[0-9a-fA-F]+$/.test(hex)
  if (!isHex) return ['Not a hex-encoded hash']

  const map = {
    32:  ['MD5'],
    40:  ['SHA-1', 'RIPEMD-160'],
    56:  ['SHA-224', 'SHA3-224'],
    64:  ['SHA-256', 'SHA3-256', 'BLAKE2s'],
    96:  ['SHA-384', 'SHA3-384'],
    128: ['SHA-512', 'SHA3-512', 'BLAKE2b'],
  }
  return map[len] || [`Unknown (${len} hex chars)`]
}

identifyHash('d41d8cd98f00b204e9800998ecf8427e')
// → ["MD5"]

identifyHash('e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855')
// → ["SHA-256", "SHA3-256", "BLAKE2s"]

import re

HASH_LENGTHS = {
    32:  ['MD5'],
    40:  ['SHA-1', 'RIPEMD-160'],
    56:  ['SHA-224', 'SHA3-224'],
    64:  ['SHA-256', 'SHA3-256', 'BLAKE2s'],
    96:  ['SHA-384', 'SHA3-384'],
    128: ['SHA-512', 'SHA3-512', 'BLAKE2b'],
}

def identify_hash(hex_string: str) -> list[str]:
    hex_string = hex_string.strip()
    if not re.fullmatch(r'[0-9a-fA-F]+', hex_string):
        return ['Not a hex-encoded hash']
    return HASH_LENGTHS.get(len(hex_string), [f'Unknown ({len(hex_string)} hex chars)'])

identify_hash('da39a3ee5e6b4b0d3255bfef95601890afd80709')
# → ['SHA-1', 'RIPEMD-160']

identify_hash('a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a')
# → ['SHA-256', 'SHA3-256', 'BLAKE2s']

package main

import (
	"fmt"
	"regexp"
)

var hexPattern = regexp.MustCompile("^[0-9a-fA-F]+$")

var hashLengths = map[int][]string{
	32:  {"MD5"},
	40:  {"SHA-1", "RIPEMD-160"},
	56:  {"SHA-224", "SHA3-224"},
	64:  {"SHA-256", "SHA3-256", "BLAKE2s"},
	96:  {"SHA-384", "SHA3-384"},
	128: {"SHA-512", "SHA3-512", "BLAKE2b"},
}

func identifyHash(hex string) []string {
	if !hexPattern.MatchString(hex) {
		return []string{"Not a hex-encoded hash"}
	}
	if algos, ok := hashLengths[len(hex)]; ok {
		return algos
	}
	return []string{fmt.Sprintf("Unknown (%d hex chars)", len(hex))}
}

func main() {
	fmt.Println(identifyHash("d41d8cd98f00b204e9800998ecf8427e"))
	// → [MD5]
}

#!/bin/bash
# Identify a hash from the command line by character count
hash="$1"

if [[ ! "$hash" =~ ^[0-9a-fA-F]+$ ]]; then
  echo "Not a hex-encoded hash"
  exit 1
fi

len=${#hash}
case $len in
  32)  echo "MD5 (128-bit)" ;;
  40)  echo "SHA-1 or RIPEMD-160 (160-bit)" ;;
  56)  echo "SHA-224 or SHA3-224 (224-bit)" ;;
  64)  echo "SHA-256 or SHA3-256 (256-bit)" ;;
  96)  echo "SHA-384 or SHA3-384 (384-bit)" ;;
  128) echo "SHA-512 or SHA3-512 (512-bit)" ;;
  *)   echo "Unknown hash length: $len chars" ;;
esac

# Usage: ./identify.sh d41d8cd98f00b204e9800998ecf8427e
# → MD5 (128-bit)