Keygenning challenge keygenme1 of wargame.vn at http://wargame.vn/re1.html

keygen1.py

import argparse

parser = argparse.ArgumentParser(description='Generate serial from username and email for the challenge keygenme1 of wargame.vn at http://wargame.vn/re1.html')
parser.add_argument('username', help='username to register')
parser.add_argument('email', help='email to register')
args = parser.parse_args()
username = args.username + chr(0xA) #fgets includes new line character
email = args.email + chr(0xA)   #fgets includes new line character

def fuzz(username):
    secret = '8k1753('
    result = ''.join([chr(ord(username[i])^ord(secret[i%7])) for i in xrange(0, len(username))])
    return result

fuzzed_username = fuzz(username)
char = 66
lenUserName = len(fuzzed_username)
lenEmail = len(email)
bkitsec = 'bkitsec'
serial = ''
for i in xrange(0,32):
    char = (ord(fuzzed_username[i % lenUserName]) + ord(email[i % lenEmail]) + char*ord(bkitsec[i % 7])) % 256
    if not char:
        char = 33
    if char > 127:
        char = 0xFF + 1 - char
    if char <= 32:
        char += 32
    if char == 127:
        char = 126
    serial += chr(char)
print "Serial: " + serial

Target keygenme1 of wargame.vn at http://wargame.vn/re1.html:
https://gist.github.com/trietptm/7a39491c97086fea080c