Python hashed password to use in different script?

Question

OK, i was unable to find this same question anywhere.. So i apologize in advance if this has been asked before.

My need is to have a script ssh into other devices at different times, to do this I need to store a password. I don't want to use plain text or base64, but I would be OK with hashing the password and I have no issue doing that. The issue is I don't know how to get the hash to be sent to the devices as a password. It just sends the hash and the login gets denied.

This is the hash script that writes to a file:

import getpass, hashlib, os

pwf = open('hashes.txt', 'w')
password = getpass.getpass()
hashpass = hashlib.sha256(password).hexdigest()
pfw.write(hashpass)

This is the 2nd script that I can pull the hash out of the file, but its still a hash.

hashes = open('hashes.txt', 'r')
for pw in hashes:
    passwrd = pw.strip()  
password = passwrd

Thats all fine and dandy, but the I cant login with the hash.. Im sure im doing something fundamentally wrong here. please let me know.

Also i left out the other ssh code as I didnt think it was relevent.

Answer 1

The entire point of a cryptographic hash is that it isn't feasible to reverse it into the original password. If you need to send the actual password, a hash will not work for you; you'd need to use an actual encryption algorithm - but then you run into a similar problem of how you store the encryption key you're using to store the password.

Either way you need a way of securely storing data on your local system that other unauthorized users can't access. Typically this is done by using key-based ssh authentication and storing the key with permissions that make it inaccessible to other users. This essentially skips the unnecessary step of encrypting/decrypting a password and instead just uses the encryption key as the authentication mechanism for ssh.

Note that there exist Python libraries that are designed for the kind of task you're doing ( ssh ing to remote systems and running commands automatically) - fabric is one of them.