def METHOD_NAME(cookie):
    salt = b''
    iterations = 1000
    key = hashlib.pbkdf2_hmac('sha256', salt, salt, iterations, 16)
    aesgcm = AESGCM(key)
    nonce = binascii.unhexlify(cookie[:24])
    ct = binascii.unhexlify(cookie[24:])
    username = str(aesgcm.decrypt(nonce, ct, None), 'ascii')
    return username