OSCE fc4.me challenge solver

#!/usr/bin/python2
# Auto solver for the OSCE challenge at fc4.me
# If you couldn't solve the challenge without this script
# You probably don't even want to try OSCE.

import hashlib
import datetime
import requests
import base64
import sys
import binascii

def main():
    # Get email address for registration.
    # It has to be valid, and it has to be the same as
    # the one you set during registration.
    if len(sys.argv) < 2:
        email=raw_input("[>] Please set an email address: ")
    else:
        email=sys.argv[1]

    # adding 'st', 'nd' or 'rd' when today date is 1st 2nd or 3rd
    # Better solution? Please share!
    today_day=int(datetime.datetime.now().strftime("%d"))
    if today_day in [1, 21, 31]:
        today=datetime.datetime.now().strftime("%A %dst of %B %Y")
    elif today_day in [2, 22]:
        today=datetime.datetime.now().strftime("%A %dnd of %B %Y")
    elif today_day in [3, 23]:
        today=datetime.datetime.now().strftime("%A %drd of %B %Y")
    else:
        today=datetime.datetime.now().strftime("%A %dth of %B %Y")

    print("[*] Today date is %s" % today)

    # hexdata = 'tryharder'
    hexdata="\x74\x72\x79\x68\x61\x72\x64\x65\x72"
    print("[*] Security string for today: %s%s" % (hexdata,today))
    m=hashlib.md5()
    m.update(("%s%s" % (hexdata,today)).encode('UTF-8'))
    dig=m.hexdigest()
    print("[*] MD5 digest: %s" % dig)

    # post request to validate the data...
    print("[*] Solving first challenge...")
    r=requests.post("http://fc4.me/fc4me.php", data={'email': email, 'securitystring': dig})

    try:
        decy=base64.b64decode(r.content[r.content.index("<blockquote>"):r.content.index("</blockquote>")].replace("<blockquote>","").replace("<br/>",""))
        print("[!] First challenge solved!")
    except Exception as e:
        print("[x] Error while solving first challenge...")
        return

    chunks = decy.split(":")

    # Registration code acquired!
    regcode = chunks[2].strip().split()[0]
    shcode = chunks[3].strip()

    print("[*] Extracting encoded registration key from aquired shellcode...")
    # the shellcode starts with a sequence of pushes with xor encoded values.
    # the idea is at the end of the push sequence, you end up with the
    # encoded registration key on the stack.
    # the shellcode then ends with a loop to decode the encoded key.
    # Instead of scraping that from memory, we can just parse the shellcode
    # to get the encoded key, and then decode it using the same logic.
    shcode_chunks=shcode.split("\\x68")[1:]
    shcode_chunks[-1]=shcode_chunks[-1][:16]

    # shcode_chunks is an array of values like '\x32\x53\xf3\x71'
    # It is little-endian now. We need to reverse each items. (eg. we want '\x71\xf3\x53\x32')
    keyarray=list()
    for c in reversed(shcode_chunks):
        valarray = c.split("\\x")[1:]
        for i in valarray:
            keyarray.append(i)

    # Our array is sorted. Let's decode each values using a simple xor
    print("[*] Encoded registration key extracted.")
    print("[*] Decoding registration key using xor key: 0x%x" % 0x41) # XOR key is always the same
    for i in range(len(keyarray)):
        keyarray[i] = int(keyarray[i], 16)^0x41

    print("[!] Registration key decoded! All the challenges are solved!")
    print("[+] Registration code: %s" % regcode)
    print("[+] Registration key: "+(''.join(chr(e) for e in keyarray))) # BOOM.

main()