import hashlib
import os

def hash_with_salt(host, salt):
	"""hash_with_salt(bytes, bytes) → bytes[32]
	Hash the host using sha256 and the give salt"""
	assert type(host) == bytes
	assert type(salt) == bytes
	m = hashlib.sha256()
	m.update(host)
	m.update(salt)
	return m.digest()

def generate_salt():
	"""generate_salt() → bytes[32]
	Generates 32 bytes of randomness using the system urandom"""
	return os.urandom(32)

def hash_host(host):
	"""hash_host(bytes) → (bytes[32]: salt, bytes[32]: hashed_host)
	Generates a salt and hashes the host with it"""
	assert type(host) == bytes
	salt = generate_salt()
	hashed_host = hash_with_salt(host, salt)
	return salt, hashed_host