HTTPS and secure cookies in Django - Step-by-Step Execution

Concept Flow - HTTPS and secure cookies

User sends HTTP request

↓

Server checks if HTTPS

No↓

Redirect to HTTPS URL

↓

User sends HTTPS request

↓

Server sets secure cookie with Secure flag

↓

Browser stores cookie only on HTTPS

↓

Subsequent requests send secure cookie only over HTTPS

↓

Server reads secure cookie safely

This flow shows how a user is redirected to HTTPS and how the server sets cookies with the Secure flag so browsers only send them over HTTPS.

Execution Sample

Django

# Redirect HTTP to HTTPS
if not request.is_secure():
    return redirect(request.build_absolute_uri().replace('http://', 'https://'))

response.set_cookie('sessionid', 'abc123', secure=True)

This Django code sets a secure cookie and redirects HTTP requests to HTTPS.

Execution Table

Step	Action	Condition	Result	Cookie Sent
1	User sends HTTP request	Request is HTTP	Redirect to HTTPS URL	No
2	User sends HTTPS request	Request is HTTPS	Process request	No (first request)
3	Server sets cookie	Set cookie with Secure=True	Cookie stored in browser with Secure flag	No (set in response)
4	User sends next HTTPS request	Request is HTTPS	Send cookie with request	Yes (cookie sent)
5	User sends HTTP request again	Request is HTTP	Redirect to HTTPS URL	No (cookie not sent over HTTP)

💡 Execution stops because user uses HTTPS and cookie is sent only over HTTPS, ensuring security.

Variable Tracker

Variable	Start	After Step 3	After Step 4	After Step 5
request.is_secure()	False (HTTP)	True (HTTPS)	True (HTTPS)	False (HTTP)
cookie 'sessionid'	Not set	Set with Secure flag	Sent with HTTPS request	Not sent with HTTP request

Key Moments - 3 Insights

Why doesn't the browser send the secure cookie over HTTP?

Because the cookie has the Secure flag set (see execution_table step 5), browsers only send it over HTTPS connections.

What happens if the user tries to access the site with HTTP?

The server redirects the user to HTTPS (execution_table step 1 and 5), ensuring all communication is secure.

When is the secure cookie actually stored in the browser?

After the server sets it in the HTTPS response (execution_table step 3), the browser stores it with the Secure flag.

Visual Quiz - 3 Questions

Look at the execution table, at which step is the secure cookie first sent by the browser?

A Step 3

B Step 4

C Step 1

D Step 5

💡 Hint

Check the 'Cookie Sent' column in the execution_table for when the cookie is sent.

According to variable_tracker, what is the value of request.is_secure() after step 3?

A False

B Undefined

C True

D None

💡 Hint

Look at the 'request.is_secure()' row and the 'After Step 3' column in variable_tracker.

If the Secure flag was not set on the cookie, what would change in the execution table?

A Cookie would be sent over HTTP requests too

B User would not be redirected to HTTPS

C Cookie would never be stored

D Server would reject the cookie

💡 Hint

Think about the Secure flag's role in restricting cookie sending (see key_moments about step 5).

Concept Snapshot

HTTPS and secure cookies in Django:
- Redirect HTTP requests to HTTPS for security
- Set cookies with secure=True to restrict sending to HTTPS only
- Browsers send secure cookies only over HTTPS connections
- Secure cookies prevent exposure over insecure HTTP
- Use request.is_secure() to detect HTTPS in Django views

Full Transcript

This visual trace shows how HTTPS and secure cookies work in Django. When a user sends an HTTP request, the server redirects them to HTTPS. Once on HTTPS, the server sets a cookie with the Secure flag. The browser stores this cookie but only sends it back on HTTPS requests, never on HTTP. This protects the cookie from being sent over insecure connections. The variable tracker shows how request.is_secure() changes from False to True when switching to HTTPS, and how the cookie is stored and sent only over HTTPS. Key moments clarify why the Secure flag matters and how redirects enforce HTTPS. The quiz tests understanding of when cookies are sent and the role of the Secure flag.

Practice

1. What is the main purpose of setting SESSION_COOKIE_SECURE = True in Django settings?

easy

A. To allow cookies on both HTTP and HTTPS

B. To make cookies accessible to JavaScript

C. To disable cookies entirely

D. To ensure cookies are only sent over HTTPS connections

Solution

1. Step 1: Understand what SESSION_COOKIE_SECURE does

   This setting tells Django to only send session cookies over HTTPS connections, preventing them from being sent over insecure HTTP.

2. Step 2: Analyze the options

   To ensure cookies are only sent over HTTPS connections correctly describes this behavior. The other options do not match the purpose of this setting.

3. Final Answer:

   To ensure cookies are only sent over HTTPS connections -> Option D

4. Quick Check:

   SESSION_COOKIE_SECURE = True means HTTPS only [OK]

Hint: Secure cookies only send on HTTPS connections [OK]

Common Mistakes:

• Thinking it makes cookies accessible to JavaScript
• Believing it disables cookies
• Assuming it allows cookies on HTTP

2. Which of the following is the correct way to enable HTTPS redirection in Django settings?

easy

A. SECURE_SSL_REDIRECT = False

B. SECURE_SSL_REDIRECT = True

C. SESSION_COOKIE_SECURE = False

D. CSRF_COOKIE_SECURE = False

Solution

1. Step 1: Identify the setting for HTTPS redirection

   The setting SECURE_SSL_REDIRECT controls whether Django redirects HTTP requests to HTTPS.

2. Step 2: Choose the correct value to enable redirection

   Setting SECURE_SSL_REDIRECT = True enables automatic redirection to HTTPS. The other options either disable security or relate to cookies.

3. Final Answer:

   SECURE_SSL_REDIRECT = True -> Option B

4. Quick Check:

   Enable HTTPS redirect with SECURE_SSL_REDIRECT = True [OK]

Hint: Set SECURE_SSL_REDIRECT to True to force HTTPS [OK]

Common Mistakes:

• Setting SECURE_SSL_REDIRECT to False disables HTTPS redirect
• Confusing cookie settings with HTTPS redirect
• Not enabling HTTPS redirect at all

3. Given the following Django settings snippet, what will happen when a user accesses the site over HTTP?

SECURE_SSL_REDIRECT = True
SESSION_COOKIE_SECURE = True
CSRF_COOKIE_SECURE = True

medium

A. The user will be redirected to the HTTPS version of the site

B. The session cookie will be sent over HTTP

C. CSRF protection will be disabled

D. The site will allow HTTP access without redirection

Solution

1. Step 1: Understand SECURE_SSL_REDIRECT = True

   This setting forces Django to redirect all HTTP requests to HTTPS automatically.

2. Step 2: Analyze cookie settings

   Both SESSION_COOKIE_SECURE and CSRF_COOKIE_SECURE ensure cookies are only sent over HTTPS, but the redirect happens first.

3. Final Answer:

   The user will be redirected to the HTTPS version of the site -> Option A

4. Quick Check:

   SECURE_SSL_REDIRECT = True causes HTTPS redirect [OK]

Hint: HTTPS redirect happens before cookies are sent [OK]

Common Mistakes:

• Thinking cookies are sent over HTTP despite redirect
• Assuming CSRF protection is disabled
• Believing HTTP access is allowed without redirect

4. You set SESSION_COOKIE_SECURE = True but notice session cookies are still sent over HTTP. What is the most likely cause?

medium

A. The site is not using HTTPS, so cookies are sent anyway

B. The browser does not support secure cookies

C. You forgot to set SECURE_SSL_REDIRECT = True

D. You need to set CSRF_COOKIE_SECURE = False

Solution

1. Step 1: Understand the role of SECURE_SSL_REDIRECT

   This setting forces HTTP requests to HTTPS, ensuring secure cookies are sent only over HTTPS.

2. Step 2: Identify why cookies are sent over HTTP

   If SECURE_SSL_REDIRECT is not enabled, users can access the site over HTTP, so cookies may be sent insecurely despite SESSION_COOKIE_SECURE.

3. Final Answer:

   You forgot to set SECURE_SSL_REDIRECT = True -> Option C

4. Quick Check:

   Enable SECURE_SSL_REDIRECT to enforce HTTPS [OK]

Hint: Enable SECURE_SSL_REDIRECT to prevent HTTP cookie sending [OK]

Common Mistakes:

• Assuming browser ignores secure cookie flag
• Thinking CSRF_COOKIE_SECURE affects session cookies
• Believing HTTPS is automatic without redirect

5. You want to secure your Django site so that session and CSRF cookies are only sent over HTTPS, and all HTTP requests redirect to HTTPS. Which combination of settings achieves this securely?

hard

A. SECURE_SSL_REDIRECT = True, SESSION_COOKIE_SECURE = True, CSRF_COOKIE_SECURE = True

B. SECURE_SSL_REDIRECT = False, SESSION_COOKIE_SECURE = True, CSRF_COOKIE_SECURE = True

C. SECURE_SSL_REDIRECT = True, SESSION_COOKIE_SECURE = False, CSRF_COOKIE_SECURE = False

D. SECURE_SSL_REDIRECT = False, SESSION_COOKIE_SECURE = False, CSRF_COOKIE_SECURE = False

Solution

1. Step 1: Ensure HTTP requests redirect to HTTPS

   Setting SECURE_SSL_REDIRECT = True forces all HTTP requests to HTTPS, preventing insecure access.

2. Step 2: Secure cookies for session and CSRF

   Setting both SESSION_COOKIE_SECURE and CSRF_COOKIE_SECURE to True ensures cookies are only sent over HTTPS connections.

3. Step 3: Evaluate other options

   The other options fail to secure either redirection or cookies properly, leaving security gaps.

4. Final Answer:

   SECURE_SSL_REDIRECT = True, SESSION_COOKIE_SECURE = True, CSRF_COOKIE_SECURE = True -> Option A

5. Quick Check:

   All three settings True secures HTTPS and cookies [OK]

Hint: Enable all three: redirect and secure cookies [OK]

Common Mistakes:

• Not enabling HTTPS redirect
• Leaving cookie secure flags False
• Assuming one setting is enough alone