Increment a number and hash it using chosen algorithm to find partial collisions

genhash.py

#!/usr/bin/env python3 

import hashlib
import whirlpool
import sys

algo = sys.argv[1]
target = sys.argv[2]

def gen_hash(algo, target):
    candidate = 0

    if algo == 'md5':
        hash_algo = lambda x: hashlib.md5(x.encode('ascii')).hexdigest()
    elif algo == 'sha1':
        hash_algo = lambda x: hashlib.sha1(x.encode('ascii')).hexdigest()
    elif algo == 'whirlpool':
        hash_algo = lambda x: whirlpool.new(x.encode('ascii')).hexdigest()

    while True:
        plaintext = str(candidate)
        hs = hash_algo(plaintext)
        if hs[:len(target)] == target:
            print(f"plaintext: {plaintext}, {algo} hash: {hs}")
            break
        candidate += 1

gen_hash(algo, target)