Test hostname against hashed entry in SSH known_hosts file

known_hosts_hash.py

import hashlib, hmac
from base64 import b64decode as b64d, b64decode as b64d

line = input('hashed known_hosts line> ').strip()
host = input('suspected host> ').strip()

_, _, e_hkey, e_hdigest = line.split()[0].encode().split(b'|')
hkey, hdigest = b64d(e_hkey), b64d(e_hdigest)

d = hmac.digest(hkey, host.encode(), hashlib.sha1)
hmac.compare_digest(hdigest, d)