python steam login process copied from http://forums.eventscripts.com/viewtopic.php?f=90&t=46941

steam_login.py

import urllib
import urllib2
import json
import time
from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_v1_5
import base64
import cookielib

uname = "----"
passwd = "----"
user_agent = 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)'

# Request key
url = 'https://steamcommunity.com/login/getrsakey/'
values = {'username' : uname, 'donotcache' : str(int(time.time()*1000))}
headers = { 'User-Agent' : user_agent }
post = urllib.urlencode(values)
req = urllib2.Request(url, post, headers)
response = urllib2.urlopen(req).read()
data = json.loads(response)

print "Get Key Success:", data["success"]

# Encode key
mod = long(str(data["publickey_mod"]), 16)
exp = long(str(data["publickey_exp"]), 16)
rsa = RSA.construct((mod, exp))
cipher = PKCS1_v1_5.new(rsa)
print base64.b64encode(cipher.encrypt(passwd))

# Login
url2 = 'https://steamcommunity.com/login/dologin/'
values2 = {
        'username' : uname,
        "password": base64.b64encode(cipher.encrypt(passwd)),
        "emailauth": "",
        "loginfriendlyname": "",
        "captchagid": "-1",
        "captcha_text": "",
        "emailsteamid": "",
        "rsatimestamp": data["timestamp"],
        "remember_login": False,
        "donotcache": str(int(time.time()*1000)),
}
headers2 = { 'User-Agent' : user_agent }
post2 = urllib.urlencode(values2)
req2 = urllib2.Request(url2, post2, headers)
response2 = urllib2.urlopen(req2).read()
data2 = json.loads(response2)

if data2["success"]:
        print "Logged in!"
else:
        print "Error, could not login:", data2["message"]

print response2

I've just updated my fork of this gist with what I used for quite some time.
Stripped that out of my project without testing it so there might contain bugs and debug stuff but it handles captcha and email auth, steam js like escaping of non-ascii characters and saves cookies to a file if thats of help for someone.

Jayme, does your own also give the 'Incorrect login' message?

Jayme, does your own also give the 'Incorrect login' message?

Yes, since end of april I guess. Worked great 'till then and, as said, I could not see any difference in the javascript steam uses.

I may have just solved it, instead of getting an 'incorrect login' I know get emailauth. Ill keep you updated and i'll say when (and how) it works completely!

EDIT: It works, I have successfully logged in. I am now cleaning up the code

FYI: I have written it in python 3 (not 2!), you also need to have pycrypto installed which you most likely already have. I will make a repo on github soon (max 5 days) and upload my project there.

Cool! Let me know what you changed or did different than me!

I uploaded it. https://github.com/wagenaartje/PySteam/blob/master/PySteam.py . It contains a lot of unnecessary headers, but I achieved it by copying the exact login process from internet explorer and including the same headers and such. I think the problem was at the session ID, I am now going to continue to remove unnecessary headers and such.

also note it does not handle captcha codes yet.

I think the problem was at the session ID

Strange. My code requests a sessionid first as well here and provides it along with all other cookies for every other GET/POST. I also tried the X-Prototype-Version header some time ago...
We'll see what you find out when you reduce the headers and/or what I find out when I have time to dig into this again ;)
Thanks for sharing! I'll follow you for now to not miss any updates on this (why the heck can't I watch this discussion...)

I'ts just that stupid twofactorcode parameter that needs to be added to the dologin POST.

damn xD

you dont need to do that. there is a library for steam link