Programming Authentication (Edexcel GCSE Computer Science)

Revision Note

Written by: James Woodhouse

Reviewed by: Lucy Kirkham

Programming Authentication

What is Authentication?

Authentication is the process of ensuring that a system is secure by asking the user to complete tasks to prove they are an authorised user of the system
Authentication is done because bots can submit data in online forms
Authentication can be done in several ways, these include
- Usernames and Passwords
- CAPTCHA
Other methods that programmers can do to authenticate the user include
- Allowing users to recover passwords via email links and SMS codes
- Encrypting data

How can authentication be programmed?

Authentication of usernames and passwords can be programmed in several ways, including using lists, databases and encryption
Students are required to be able to program looking up usernames and passwords using a list/array
To do this successfully, a 2-dimensional list/array will be used

Python example
# Set a Boolean flag to track if the username is found `found = False` # List of usernames and corresponding passwords `usernames = [` `["Dave", "1"],` `["Steve", "2"],` `["James", "3"],` `["Alice", "4"],` `["Stephanie", "5"]` `]` # Ask the user to input their username `user = input("Enter your username: ")` # Loop through each username in the list `for i in range(len(usernames)):` # Check if the entered username matches any in the list `if user == usernames[i][0]:` `found = True` # Set the flag to indicate the username is found `password = input("Enter your password: ")` # Ask for the password # Check if the entered password matches the password associated with the username `if password == usernames[i][1]:` `print("Welcome")` `else:` `print("Wrong password")` # Check if the username was not found `if not found:` `print("User not found")`

Python example

# Set a Boolean flag to track if the username is found

found = False

# List of usernames and corresponding passwords

usernames = [

["Dave", "1"],

["Steve", "2"],

["James", "3"],

["Alice", "4"],

["Stephanie", "5"]

]

# Ask the user to input their username

user = input("Enter your username: ")

# Loop through each username in the list

for i in range(len(usernames)):

# Check if the entered username matches any in the list

if user == usernames[i][0]:

found = True # Set the flag to indicate the username is found

password = input("Enter your password: ") # Ask for the password

# Check if the entered password matches the password associated with the username

if password == usernames[i][1]:

print("Welcome")

else:

print("Wrong password")

# Check if the username was not found

if not found:

print("User not found")

Last updated: 8 April 2024

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