Little python3.3 script to show information about ssh public keys from key files or known_hosts files.

0.check_keys.py_example.md

SSH key info for pubkeys, known_hosts, and github users

Usage:
  check_keys.py hosts [<FILE>]
  check_keys.py key [<FILE>...]
  check_keys.py github <user>


$ check_hosts.py github cagerton
[
	{
		"fingerprint": "87:bf:d6:af:b2:04:c8:01:25:69:40:96:ea:8f:f4:50", 
		"bits": 2048, 
		"meta": "cagerton (RSA)"
	}
]
$ ssh-keygen -b 4096 -f output 
$ ssh-keygen -t dsa -f output_d
$ check_hosts.py key *.pub 

{
  "fingerprint": "79:ac:f3:1f:7e:a1:22:2f:b9:31:e9:75:b9:c2:0f:18", 
	"bits": 4096, 
	"meta": "cda@niobate.local (RSA)"
}
{
	"fingerprint": "ef:18:c6:8d:79:e5:28:89:2c:af:00:5a:be:5e:3c:38", 
	"bits": 1024, 
	"meta": "cda@niobate.local (DSA)"
}

1.check_keys.py

#!/usr/bin/env python3.3
"""Check Keys script
Usage:
  check_keys.py hosts [<FILE>]
  check_keys.py key [<FILE>...]
  check_keys.py github <user>
"""
import subprocess, tempfile, os, re, json, docopt, urllib.parse, urllib.request

def guess_hosts_file():
  return os.path.join(os.path.expanduser('~'),'.ssh','known_hosts')

def github_keys(username):
  url = "https://api.github.com/users/%s/keys" % urllib.parse.quote(username)
  with urllib.request.urlopen(url) as req:
    resp = [ k['key'] for k in json.loads(req.read().decode('utf8'))]
    return [ parse_keytext(t + ' ' + username) for t in resp ]

def parse_keytext(text):
  with tempfile.NamedTemporaryFile() as tmp:
    tmp.write(text.encode('utf8'))
    tmp.flush()
    return parse_keyfile(tmp.name)

def parse_keyfile(filename):
  res = subprocess.check_output(['ssh-keygen','-lf', filename]).decode('utf8')
  parsed = re.match(r'(?P<bits>\d+)\s+(?P<fingerprint>[\da-f:]+)\s+(?P<meta>.*)', res)
  return {
     'bits': int(parsed.group('bits')),
     'fingerprint': parsed.group('fingerprint'),
     'meta': parsed.group('meta'),
  }

def parse_known_hosts(known_hosts_file):
  key_map = {}
  with open(known_hosts_file) as f:
    lines = [ line for line in f.read().split("\n") if len(line) > 0 ]
  for l in lines:
      key = parse_keytext(("%s %s" % (keytype, key)).encode('utf8'))
      if key['fingerprint'] not in key_map:
        key_map[key['fingerprint']] = {'hosts':[],'bits':key['bits'],}
      key_map[key['fingerprint']]['hosts'].append(host)
  return key_map

def format_data(key_map):
  return json.dumps(key_map, indent='\t')

if __name__ == "__main__":
  args = docopt.docopt(__doc__, version='Project.py concept.')
  if args['hosts']:
    known_hosts_file = (args['<FILE>']+[guess_hosts_file()])[0]
    key_map = parse_known_hosts(known_hosts_file)
    print(format_data(key_map))
  elif args['key']:
    for keyfile in args['<FILE>']:
      print(format_data(parse_keyfile(keyfile)))
  elif args['github']:
    print(format_data(github_keys(args['<user>'])))