Password storage best practices in Flask - Step-by-Step Execution

Concept Flow - Password storage best practices

User enters password

↓

Generate salt

↓

Hash password + salt

↓

Store salt + hash in DB

↓

User login attempt

↓

Retrieve salt + hash from DB

↓

Hash entered password + salt

↓

Compare hashes

↓

Grant or deny access

This flow shows how a password is salted and hashed before storage, then verified on login by hashing the entered password with the stored salt and comparing hashes.

Execution Sample

Flask

from flask import Flask, request
from werkzeug.security import generate_password_hash, check_password_hash

# Store hashed password
hashed = generate_password_hash('mypassword')

# Verify password
check_password_hash(hashed, 'mypassword')

This code hashes a password securely and then checks if a given password matches the stored hash.

Execution Table

Step	Action	Input	Output	Notes
1	User enters password	'mypassword'	Password string	Raw password input
2	Generate salt and hash	'mypassword'	Hashed password string	Salt is generated internally by generate_password_hash
3	Store hashed password	Hashed password string	Saved in database	Only hashed password stored, never raw password
4	User login attempt	'mypassword'	Password string	User inputs password again
5	Retrieve stored hash	User ID	Hashed password string	Get stored hash from DB
6	Hash entered password with salt	'mypassword'	Hashed password string	Salt is extracted from stored hash internally
7	Compare hashes	Hashed entered password vs stored hash	True or False	True if passwords match
8	Grant or deny access	Comparison result	Access granted or denied	Access granted only if True

💡 Process stops after access is granted or denied based on password match

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 5	After Step 6	After Step 7
password	None	'mypassword'	'mypassword'	'mypassword'	'mypassword'	'mypassword'
salt	None	Generated internally	Stored internally in hash	Retrieved internally	Used internally	Used internally
hashed_password	None	Generated hash string	Stored in DB	Retrieved from DB	Computed from input	Compared
check_result	None	None	None	None	None	True or False

Key Moments - 3 Insights

Why do we never store the raw password in the database?

Storing raw passwords is risky because if the database is leaked, attackers get all passwords. The execution_table shows we only store the hashed password (Step 3), which protects raw passwords.

What is the role of salt in password hashing?

Salt adds random data to the password before hashing to prevent attackers from using precomputed tables. The salt is generated and stored inside the hash (Step 2 and Step 3) and reused during verification (Step 6).

How does check_password_hash verify the password?

It extracts the salt from the stored hash, hashes the entered password with it, then compares hashes (Step 6 and Step 7). This ensures the entered password matches without storing raw passwords.

Visual Quiz - 3 Questions

Look at the execution_table, what is stored in the database after Step 3?

A Hashed password string with salt

B Salt only

C Raw password string

D User's plain text password

💡 Hint

Check Step 3 in execution_table where it says what is stored in the database.

At which step does the system compare the entered password with the stored password?

A Step 5

B Step 6

C Step 7

D Step 8

💡 Hint

Look at the 'Compare hashes' action in the execution_table.

If the salt was not used, how would the execution_table change?

A Step 6 would not hash the password

B Step 2 would not generate salt

C Step 7 would always return True

D Step 3 would store raw password

💡 Hint

Salt generation is shown in Step 2; without salt, that step changes.

Concept Snapshot

Password Storage Best Practices in Flask:
- Never store raw passwords.
- Use generate_password_hash() to hash with salt.
- Store only the hashed password.
- Use check_password_hash() to verify passwords.
- Salt is handled internally to protect against attacks.

Full Transcript

This visual execution shows how password storage works in Flask using best practices. When a user enters a password, the system generates a salt and hashes the password combined with the salt. This hashed password is stored in the database, never the raw password. On login, the system retrieves the stored hash and salt, hashes the entered password with the same salt, and compares the two hashes. If they match, access is granted. This process protects user passwords even if the database is compromised.