xor

def read(filename):
    text = ''
    with open(filename, 'r', encoding='ascii') as f:
        for line in f:
            text += line
    return text

def encode_text(text, key):
    ans = ''
    for i in range(0,len(text), 24):
        line = text[i:i+24]
        for j, l in enumerate(line):
            ans += xor(l, key[j])
    return (ans)


def xor(a, b):
    a = ord(a)
    b = ord(b)
    return chr(a^b)

def get_frequensy(text, i):
    frec = {}
    for sym in text[i::24]:
        if sym in frec:
            frec[sym] += 1
        else:
            frec[sym] = 1
    i = ''
    for t in sorted(frec, key=lambda a: frec[a]):
        i = t
    return i

def get_word(text, f):
    d = ''
    popular = get_frequensy(text, f)
    for letter in text[f::24]:
        if letter == popular:
            d = xor(popular, '_')
            break
    return(d)

if __name__ == "__main__":
    text = read('encryptedtext')
    encr_text = encode_text(text, 'qwertyuiopasdfghjklzxcvb')
    decr_text = encode_text(encr_text, 'qwertyuiopasdfghjklzxcvb')
    for i in range(len(text)):
        if text[i] != decr_text[i]:
            raise TypeError(i)