#! /usr/bin/python

# ignoblekeygen.pyw, version 1

# To run this program install Python 2.6 from <http://www.python.org/download/>
# and PyCrypto from http://www.voidspace.org.uk/python/modules.shtml#pycrypto
# (make sure to install the version for Python 2.6).  Save this script file as
# ignoblekeygen.pyw and double-click on it to run it.

# Revision history:
#   1 - Initial release

"""
Generate Barnes & Noble EPUB user key from name and credit card number.
"""

from __future__ import with_statement

__license__ = 'GPL v3'

import sys
import os
import hashlib
import Tkinter
import Tkconstants
import tkFileDialog
import tkMessageBox

try:
    from Crypto.Cipher import AES
except ImportError:
    AES = None

def normalize_name(name):
    return ''.join(x for x in name.lower() if x != ' ')

def generate_keyfile(name, ccn, outpath):
    name = normalize_name(name) + '\x00'
    ccn = ccn + '\x00'
    name_sha = hashlib.sha1(name).digest()[:16]
    ccn_sha = hashlib.sha1(ccn).digest()[:16]
    both_sha = hashlib.sha1(name + ccn).digest()
    aes = AES.new(ccn_sha, AES.MODE_CBC, name_sha)
    crypt = aes.encrypt(both_sha + ('\x0c' * 0x0c))
    userkey = hashlib.sha1(crypt).digest()
    with open(outpath, 'wb') as f:
        f.write(userkey.encode('base64'))
    return userkey

def cli_main(argv=sys.argv):
    progname = os.path.basename(argv[0])
    if AES is None:
        print "%s: This script requires PyCrypto, which must be installed " \
              "separately.  Read the top-of-script comment for details." % \
              (progname,)
        return 1
    if len(argv) != 4:
        print "usage: %s NAME CC# OUTFILE" % (progname,)
        return 1
    name, ccn, outpath = argv[1:]
    generate_keyfile(name, ccn, outpath)
    return 0

class DecryptionDialog(Tkinter.Frame):
    def __init__(self, root):
        Tkinter.Frame.__init__(self, root, border=5)
        self.status = Tkinter.Label(self, text='Enter parameters')
        self.status.pack(fill=Tkconstants.X, expand=1)
        body = Tkinter.Frame(self)
        body.pack(fill=Tkconstants.X, expand=1)
        sticky = Tkconstants.E + Tkconstants.W
        body.grid_columnconfigure(1, weight=2)
        Tkinter.Label(body, text='Name').grid(row=1)
        self.name = Tkinter.Entry(body, width=30)
        self.name.grid(row=1, column=1, sticky=sticky)
        Tkinter.Label(body, text='CC#').grid(row=2)
        self.ccn = Tkinter.Entry(body, width=30)
        self.ccn.grid(row=2, column=1, sticky=sticky)
        Tkinter.Label(body, text='Output file').grid(row=0)
        self.keypath = Tkinter.Entry(body, width=30)
        self.keypath.grid(row=0, column=1, sticky=sticky)
        self.keypath.insert(0, 'bnepubkey.b64')
        button = Tkinter.Button(body, text="...", command=self.get_keypath)
        button.grid(row=0, column=2)
        buttons = Tkinter.Frame(self)
        buttons.pack()
        botton = Tkinter.Button(
            buttons, text="Generate", width=10, command=self.generate)
        botton.pack(side=Tkconstants.LEFT)
        Tkinter.Frame(buttons, width=10).pack(side=Tkconstants.LEFT)
        button = Tkinter.Button(
            buttons, text="Quit", width=10, command=self.quit)
        button.pack(side=Tkconstants.RIGHT)

    def get_keypath(self):
        keypath = tkFileDialog.asksaveasfilename(
            parent=None, title='Select B&N EPUB key file to produce',
            defaultextension='.b64',
            filetypes=[('base64-encoded files', '.b64'),
                       ('All Files', '.*')])
        if keypath:
            keypath = os.path.normpath(keypath)
            self.keypath.delete(0, Tkconstants.END)
            self.keypath.insert(0, keypath)
        return

    def generate(self):
        name = self.name.get()
        ccn = self.ccn.get()
        keypath = self.keypath.get()
        if not name:
            self.status['text'] = 'Name not specified'
            return
        if not ccn:
            self.status['text'] = 'Credit card number not specified'
            return
        if not keypath:
            self.status['text'] = 'Output keyfile path not specified'
            return
        self.status['text'] = 'Generating...'
        try:
            generate_keyfile(name, ccn, keypath)
        except Exception, e:
            self.status['text'] = 'Error: ' + str(e)
            return
        self.status['text'] = 'Keyfile successfully generated'

def gui_main():
    root = Tkinter.Tk()
    if AES is None:
        root.withdraw()
        tkMessageBox.showerror(
            "Ignoble EPUB Keyfile Generator",
            "This script requires PyCrypto, which must be installed "
            "separately.  Read the top-of-script comment for details.")
        return 1
    root.title('Ignoble EPUB Keyfile Generator')
    root.resizable(True, False)
    root.minsize(300, 0)
    DecryptionDialog(root).pack(fill=Tkconstants.X, expand=1)
    root.mainloop()
    return 0

if __name__ == '__main__':
    if len(sys.argv) > 1:
        sys.exit(cli_main())
    sys.exit(gui_main())