AARHUS
AARON
ABABA
ABACK
ABAFT
ABANDON
ABANDONED
ABANDONING
ABANDONMENT
ABANDONS
ABASE
ABASED
ABASEMENT
ABASEMENTS
ABASES
ABASH
ABASHED
ABASHES


ZEROTH
ZEST
ZEUS
ZIEGFELD
ZIEGFELDS
ZIEGLER
ZIGGY
ZIGZAG
ZILLIONS
ZIMMERMAN
ZINC
ZION
ZIONISM
ZIONIST
ZIONISTS
ZIONS
ZODIAC
ZOE
ZOMBA
ZONAL
ZONALLY
ZONE
ZONED
ZONES
ZONING
ZOO
ZOOLOGICAL
ZOOLOGICALLY
ZOOM
ZOOMS
ZOOS
ZORN
ZOROASTER
ZOROASTRIAN
ZULU
ZULUS
ZURICH

"""
Brute force password breaker using a dictionary containing
English words.
"""

import sys
import PyPDF2
from pathlib import Path

def get_filename_from_user() -> Path:
    """Asks for a path from the User"""
    while True:
        filename: str = input("Enter filename in folder of script:")
        path: Path = Path(sys.path[0], filename)

        if path.is_file():
            return path.as_posix()
        print("File doesn't existn")


def decrypt(pdf_filename: Path, password: str) -> bool:
    """
    Try to decrypt a file. If not successful a false is returned.
    If the file passed is not encrypted also a false is passed
    """
    with open(pdf_filename, 'rb') as pdf_file:
        pdf_reader = PyPDF2.PdfFileReader(pdf_file)
        pdf_reader.decrypt(password)
        pdf_writer = PyPDF2.PdfFileWriter()

        try:
            for page_number in range(pdf_reader.numPages):
                pdf_writer.addPage(pdf_reader.getPage(page_number))
        except PyPDF2.utils.PdfReadError:
            return False

        new_name: str = pdf_filename.stem + "_decrypted.pdf"
        filename_decrypted = pdf_filename.parent / new_name

        with open(filename_decrypted, 'wb') as pdf_file_decrypted:
            pdf_writer.write(pdf_file_decrypted)
    return True


def break_encryption(pdf_filename: Path, dictionary_filename: str) -> bool:
    """Try's out words from a dictionary to break encryption"""
    with open(dictionary_filename, 'r') as dictionary_file:
        keyword: str = dictionary_file.readline().strip()

        if decrypt(pdf_filename, keyword):
            return keyword
        if decrypt(pdf_filename, keyword.lower()):
            return keyword.lower()

        while keyword:
            keyword = dictionary_file.readline().strip()

            if decrypt(pdf_filename, keyword):
                return keyword
            if decrypt(pdf_filename, keyword.lower()):
                return keyword.lower()
    return None


def pdf_password_breaker():
    """main loop"""
    filename: Path = get_filename_from_user()
    password: str = break_encryption(filename, "dictionary.txt")

    if password:
        print("File unlocked. Password was:" + password)
        return
    print("File could not be unlocked")

if __name__ == "__main__":
    pdf_password_breaker()