vigenere cipher hacking script

main.py

import math

def duplicates(vigenere):
    strings = []
    duplicates = set()
    for index in range(len(vigenere)):
        string = ""
        for i in range(3):
            if index + i < len(vigenere):
                string += vigenere[index + i]
        if string in strings:
            duplicates.add(string)
        strings.append(string)
    return duplicates

def spacings(vigenere, duplicate):
    spacings = []
    for i in range(vigenere.count(duplicate)):
        first_occurence = vigenere.index(duplicate)
        vigenere = vigenere[(first_occurence + 3):]
        second_occurence = vigenere.find(duplicate)
        if second_occurence != -1:
            second_occurence += first_occurence + 3
            spacings.append(second_occurence - first_occurence)
    return spacings

def divisors(number):
    divisors = []
    current_divisor = 2
    while current_divisor <= number / 2:
        if number % current_divisor == 0:
            divisors.add(current_divisor)
        current_divisor += 1
    return divisors

encrypted = """
KELXTNAZYXJYVGYNRFWANEWCHZCJVR
UHCSEHZAOXKEVSMJVFAAXYIEOANYIN
SLXNIZLNMHLRUUHIMUYGYYYRZANYIE
ZPCYDGLKYHOQLNMHLAHBYQYAKPZNJS
ZIWMANZIHXSUYELPEZZIWMLVLRQJMG
KRUZWFLNQNIRPNYQIEJHYASELRNWES
OIYWEHJHGFRPORCSHIPEBXEUHUWMQN
UCBMEHMEHRMFAELXEUKAMXIFDOUSHR
YSUZGUUIWMXIPEFFRQLRMNWGOECSDR
YHUWHG
""".upper().replace("\n", "")
for duplicate in duplicates(encrypted):
    print(f'{duplicate}: {spacings(encrypted, duplicate)}')