Super Basic Python 3 Google Play Downloader with Python-Requests

gistfile1.py

# Read title! Should be able to download any apk of any version, as long
# as it's free. Paid apps are not supported, even if you've paid for them
# (should be easy to implement, but I haven't bought any apps yet). 

# PyPI "requests"
import requests
import io

# Step 0. Google Constants + Inputs
url_root = 'https://android.clients.google.com/'

# Enter your login details here
email      = '[email protected]'
password   = 'Password'
android_id = 'FFFFFFFFFFFFFFFF'

# APK name you want to download here.
packname   = 'com.google.android.gms'
# APK version you want, or None for latest.
version    = None

def rbitshift(v, b):
  return v >> b, v & (2**b - 1)

def read_uleint(s, l = 4):
  b = s.read(l)
  if not b:
    raise EOFError
  return int.from_bytes(b, 'little')

def read_ulelong(s):
  return read_uleint(s, 8)

def read_uleb128(s):
  c, d, v = 1, 0, 0
  while c:
    c, b = rbitshift(read_uleint(s, 1), 7)
    v += b << d 
    d += 7
  return v

def read_pb_bytes(s):
  return s.read(read_uleb128(s))

pb_codecs = [
  read_uleb128,  # 0
  read_ulelong,  # 1
  read_pb_bytes, # 2
  None, None,
  read_uleint    # 5
]

def read_pb_key(s):
  return rbitshift(read_uleb128(s), 3)

def read_pb_field(s):
  k, t = read_pb_key(s)
  return k, pb_codecs[t](s)

def parse_pb_dict(data):
  data, d = io.BytesIO(data), {}
  try:
    while True:
      d.update([read_pb_field(data)])
  except EOFError:
    pass
  return d

def parse_pb_path(v, *path):
  if len(path):
    return parse_pb_path(parse_pb_dict(v)[path[0]], *path[1:])
  return v

def parse_utf8(s):
  return s.decode('UTF-8')

# Step 1. Login to Google

session = requests.Session()

data = session.post(
  url_root + 'auth',
  data = {
    "Email":   email,
    "Passwd":  password,
    "service": 'androidmarket',
  }).text
auth = dict(map(lambda s: s.split('='), data.split()))['Auth']

session.headers = {
  'Authorization':   'GoogleLogin auth=' + auth,
  'User-Agent':      'Android- (api=1,versionCode=8011000)',
  'X-DFE-Device-Id': android_id,
}

# Step 2. Get Latest Version

if not version:
  data = session.get(
    url_root + 'fdfe/details',
    params = {
      'doc': packname
    }).content
    
  version = parse_pb_path(data, 1, 2, 4, 13, 1, 3)

# Step 3. Get Download URL + Auth

data = session.post(
  url_root + 'fdfe/purchase',
  data = {
    'doc': packname,
    'vc':  version,
    #'ot':  1, # not needed?
  }).content

tmp = parse_pb_path(data, 1, 4, 39, 8)
url = parse_pb_path(tmp, 3)
mda = parse_pb_path(tmp, 5, 2)

# Step 4. Download APK file

apk = requests.get(
  parse_utf8(url),
  cookies = {
    'MarketDA': str(int(mda))
  }
).content

# 'apk' is now your apk file ready to read or save to file!
# Alternatively, open as a zip file to read:
import zipfile
zf = zipfile.ZipFile(io.BytesIO(apk))

Currently no longer works - Google changed the interface slightly - the APK version number is no longer stored in 1/2/4/13/1/3.