from Zahid Hussain
Hey folks! It's me again – Zahid Hussain, i guess i won't need much introduction if you have read my other posts! The Python session was conducted on 22 September 2019 by Rahul Bhai. This particular session was a little hard(nothing that we can't understand, right?) from the previous one, our main aim of the session was to make an ID generation system with authentication system. In layman's terms – Authentication is the process of determining whether someone or something is, in fact, who or what it declares. Authentication can involve highly complex and secure methods or can be very simple. The simplest form of authentication is the transmission of a shared password between entities wishing to authenticate each other.
Rahul bhai first told us about loops – if we sometimes want to do something repeatedly, or for a number of times, or for a number of things, we use loops and they make our life easier. 1) While loop – while loop is used to execute a block of statements repeatedly until a given a condition is satisfied. And when the condition becomes false, the line immediately after the loop in program is executed. syntax :
while condition:
statement1
statement2
example :
n = 0
while n < 11:
print(n)
n += 1
Pro tip : We generally use a while loop, when we don't know how many times exactly does the loop need to run.
2)For loop – A for loop is used for iterating over a sequence (that is either a list, a tuple, a dictionary, a set, or a string). P.S : lists are basically arrays which are a structured way of storing stuff. example :
fruits = ["apple", "banana", "cherry"]
for x in fruits:
print(x)
We then move onto special inbuilt functions.
1) len function – The len function returns the length of anything.
example :
a = [ 1, 342, 223, 'India', 'Fedora']
print(len(a))
2)range function – The range function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number.
example :
x = range(6)
for n in x:
print(n)
Then we learned about reading/writing to files. One way of reading from a file is by using a while loop. example :
with open('test.txt') as f:
text = f.readline()
print(text)
To write to a file :
with open('python.txt', 'w') as f:
f.write('Python's the best!!')
There are other functions as well for this – f.read(), f.readlines().
The main difference between readline() and readlines() is :
readlines() – reads all the lines and put them in 'list'(between these [ ]) and displays them with each line ending with'\n'.
readline() – reads a single line from the file; a newline character (\n) is left at the end of the string, and is only omitted on the last line of the file if the file doesn’t end in a newline.
The next order of business was to learn about functions – function is a group of related statements that perform a specific task.Functions help break our program into smaller and modular chunks. As our program grows larger and larger, functions make it more organized and manageable.Furthermore, it avoids repetition and makes code reusable. example :
def my_function():
print("Hello from a function")
Before we get into actually programming the ID Generation system, there are few important things to learn -
#> isalpha – isalpha() is a built-in method used for string handling. The isalpha() methods returns “True” if all characters in the string are alphabets, Otherwise, It returns “False”.
#> split – split() method returns a list of strings after breaking the given string by the specified separator.
#>PIP – PIP is a package manager for Python packages. A package contains all the files you need for a module. Modules are Python code libraries you can include in your project.
#> Vulture – It's a tool to automatically find which part of your code is unused. To install vulture (type the code in terminal) :
pip install vulture
#> texttable – This is a python library for printing tables in a pretty format. To install texttable (type the code in terminal) :
pip install texttable
#> getpass – getpass() prompts the user for a password without echoing. The getpass module provides a secure way to handle the password prompts where programs interact with the users via the terminal.
#> Hashing – Hashing is way of generating a value or values from a string of text using a mathematical function, such that it's (nearly) impossible to find it's inverse, it's like a one way ticket!
In python hashlib module implements a common interface to many different secure hash and message digest algorithms.
example :
from hashlib import sha256
print(sha256(b'<yourstrongpassword>').hexdigest())
After learning the necessary things, we can move on to the actual code of our ID Generation System :
from getpass import getpass
import hashlib
from texttable import Texttable
from hashlib import sha256
hashed_pass = sha256(b'yourstrongpassword').hexdigest()
with open('hashed_password.txt', 'w') as f:
f.write(hashed_pass)
LOGO = r"""
█████╗███╗ █████╗ ██╗ ██████╗██████████████╗
██╔══██████╗ ██████║ ██║ ██╔═══████╔════██╔════╝
█████████╔████╔████║ █████████║ ████████████████╗
██╔══████║╚██╔╝████║ ██╚════██║ ██╚════██╚════██║
██║ ████║ ╚═╝ ██╚██████╔╝ ╚██████╔██████████████║
╚═╝ ╚═╚═╝ ╚═╝╚═════╝ ╚═════╝╚══════╚══════╝
"""
def validate_name(name):
for part in name.split():
if not part.isalpha():
return False
return True
def take_name_input(prompt):
name = input(prompt)
while not validate_name(name):
print("You did not enter the name correctly, please try again!")
name = input(prompt)
return name
def print_id(u_info):
table = Texttable()
table.add_rows([[f"{LOGO} \n MEMBER - {u_info[0]}"],
[f"Slack Username: {u_info[1]}"],
[f"MOTHER'S NAME: {u_info[2]}"],
[f"FATHER'S NAME: {u_info[3]}"]
])
print(table.draw())
def read_hash(filename):
with open(filename, "r") as f:
hash = f.readline()
return hash
def authenticate(password):
correct_hash = read_hash("hashed_password.txt")
hashed_password = hashlib.sha256(password.encode('utf-8')).hexdigest()
if hashed_password == correct_hash:
print("[INFO] Successfully authenticated!")
return True
print("Authentication failed! You cannot print ID")
return False
def get_user_info():
u_info = []
u_info.append(take_name_input("Name of applicant: "))
u_info.append(input("Slack username: "))
u_info.append(take_name_input("Mother's name: "))
u_info.append(take_name_input("Father's name: "))
return u_info
def main():
password = getpass("Enter admin password: ")
if authenticate(password):
u_info = get_user_info()
print_id(u_info)
if __name__ == '__main__':
main()
#> append function – It is used to add something to the end of the list.
Before executing code, Python interpreter reads source file and define few special variables/global variables. If the python interpreter is running that module (the source file) as the main program, it sets the special name variable to have a value “main”. If this file is being imported from another module, name will be set to the module’s name. Module’s name is available as value to name global variable. A module is a file containing Python definitions and statements. The file name is the module name with the suffix .py appended.
