Password hashing with Werkzeug in Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of password hash check

What will be the output of this Flask code snippet using Werkzeug's password hashing?

Flask

from werkzeug.security import generate_password_hash, check_password_hash

hashed = generate_password_hash('mypassword')
result = check_password_hash(hashed, 'mypassword')
print(result)

A SyntaxError

B False

C TypeError

D True

💡 Hint

Check if the password matches the hash using check_password_hash.

The generate_password_hash creates a hashed password string. The check_password_hash returns True if the password matches the hash.

❓ Predict Output

intermediate

Result of checking wrong password

What will be the output of this code when checking a wrong password?

Flask

from werkzeug.security import generate_password_hash, check_password_hash

hashed = generate_password_hash('secret123')
result = check_password_hash(hashed, 'wrongpass')
print(result)

A False

B True

C ValueError

D None

💡 Hint

Check_password_hash returns False if password does not match.

The password 'wrongpass' does not match the hashed 'secret123', so check_password_hash returns False.

📝 Syntax

advanced

Identify the syntax error in password hashing code

Which option contains a syntax error when using Werkzeug's password hashing functions?

Flask

from werkzeug.security import generate_password_hash

hashed = generate_password_hash('pass123')

A hashed = generate_password_hash('pass123', method='sha256')

B hashed = generate_password_hash('pass123')

C hashed = generate_password_hash('pass123', method=sha256)

D hashed = generate_password_hash('pass123', salt_length=8)

💡 Hint

Check if method argument is passed as a string or variable.

The method parameter must be a string like 'sha256'. Passing sha256 without quotes causes a NameError or syntax error.

❓ component_behavior

advanced

Behavior of password hash with different salt lengths

What is the effect of changing the salt_length parameter in generate_password_hash?

Flask

from werkzeug.security import generate_password_hash

hash1 = generate_password_hash('mypassword', salt_length=8)
hash2 = generate_password_hash('mypassword', salt_length=16)
print(hash1 == hash2)

A False, hashes differ because salt length changes the hash

B True, hashes are always the same regardless of salt length

C TypeError, salt_length is not a valid parameter

D ValueError, salt_length must be 12

💡 Hint

Salt length affects the randomness added to the hash.

Changing salt_length changes the salt used, so hashes differ even for the same password.

🔧 Debug

expert

Debugging password hash verification failure

A developer uses this code but password verification always fails. What is the cause?

Flask

from werkzeug.security import generate_password_hash, check_password_hash

password = 'admin123'
hash_pw = generate_password_hash(password)

# Later in code
result = check_password_hash(password, hash_pw)
print(result)

A password variable is not a string

B check_password_hash arguments are reversed; first should be hash, second password

C check_password_hash requires bytes, not strings

D generate_password_hash returns None, causing failure

💡 Hint

Check the order of arguments in check_password_hash.

The check_password_hash function expects the hashed password first, then the plain password. Reversing them causes verification to fail.