User authentication basics in Raspberry Pi - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this simple password check?

Consider this Python code snippet running on a Raspberry Pi. What will it print if the user enters the password 'raspberry'?

Raspberry Pi

password = input('Enter password: ')
if password == 'raspberry':
    print('Access granted')
else:
    print('Access denied')

A SyntaxError

B Access denied

C Access granted

D No output

💡 Hint

Check the exact string compared in the if condition.

The code compares the input to the string 'raspberry'. If they match exactly, it prints 'Access granted'. Otherwise, it prints 'Access denied'.

🧠 Conceptual

intermediate

Which method securely stores passwords on Raspberry Pi?

When building a user login system on a Raspberry Pi, which method is best to store user passwords securely?

A Store passwords hashed with a salt

B Store passwords as plain text in a file

C Store passwords encrypted with a reversible key

D Store passwords in a public shared folder

💡 Hint

Think about what makes it hard for attackers to recover the original password.

Hashing passwords with a salt means passwords are transformed into a fixed string that cannot be reversed easily. This protects passwords even if the storage is compromised.

🔧 Debug

advanced

Why does this Raspberry Pi login script always deny access?

Look at this code snippet. It should grant access if the password is 'pi123', but it always prints 'Access denied'. What is the problem?

Raspberry Pi

password = input('Enter password: ')
if password is 'pi123':
    print('Access granted')
else:
    print('Access denied')

A The print statements are reversed

B The input function is not reading the password

C The string 'pi123' is misspelled

D Using 'is' instead of '==' causes the problem

💡 Hint

Check how string comparison works in Python.

The 'is' operator checks if two variables point to the same object, not if their values are equal. For string value comparison, '==' must be used.

📝 Syntax

advanced

Identify the syntax error in this user authentication code

Which option contains the correct syntax for this Raspberry Pi Python login snippet?

Raspberry Pi

password = input('Password: ')
if password == 'secret'
    print('Welcome!')
else:
    print('Try again')

A Add a colon ':' after the if condition

B Remove the else block

C Change '==' to '=' in the if condition

D Indent the print statements less

💡 Hint

Python requires a specific punctuation after conditions.

In Python, an if statement must end with a colon ':' before the indented block.

🚀 Application

expert

How many users can this Raspberry Pi authentication dictionary hold?

Given this dictionary storing usernames and hashed passwords, how many users are registered?

Raspberry Pi

users = {
    'alice': '5f4dcc3b5aa765d61d8327deb882cf99',
    'bob': '202cb962ac59075b964b07152d234b70',
    'carol': '098f6bcd4621d373cade4e832627b4f6'
}
print(len(users))

A 2

B 3

C 0

D 4

💡 Hint

Count the number of keys in the dictionary.

The dictionary has three keys: 'alice', 'bob', and 'carol'. The len() function returns the number of keys.