Session Vs JWT: The Differences You May Not Know!

Summary

This video explores two prevalent web authentication methods: session-based and JWT (Json Web Tokens). It outlines the process flow for each, highlighting their pros and cons. Session-based authentication is server-centric, storing data and issuing session IDs, which are easy to revoke but may add latency in distributed systems. JWTs, on the other hand, embed user data within tokens, offering a stateless solution suitable for microservices and third-party services, with refresh tokens enhancing security. The choice between them hinges on specific application needs and architecture.

Takeaways

• 🔒 **Session-Based Authentication**: The server creates and stores session data, using a unique session ID to authenticate requests.
• 🍪 **Session ID in Cookies**: A session ID is sent back to the client, usually in the form of a cookie, which is then sent with subsequent requests.
• 🗃️ **Centralized Session Store**: In distributed systems, a centralized session store like Redis or a distributed SQL database is used for session data access by multiple servers.
• 🚫 **Session Revocation**: Sessions can be easily revoked by the server, which is advantageous for security in case of account compromise.
• 🔄 **Complexity in Distributed Systems**: Using a centralized session store adds complexity and latency due to the need for server requests to the session store.
• 🔐 **JWT Authentication**: JSON Web Tokens (JWTs) are generated and signed by the server with a secret key to ensure token integrity.
• 🔑 **Token Storage**: Clients store JWTs, typically in local storage or cookies, and send them in request headers for authentication.
• 📈 **Stateless Nature of JWTs**: Unlike sessions, JWTs do not require the server to store any session state, as all necessary data is contained within the token.
• 🛡️ **Signing Algorithms**: JWTs can be signed using HMAC, RSA, or ECDSA, with the choice depending on security requirements and system architecture.
• ⏱️ **Token Expiration Handling**: JWTs can be vulnerable to misuse if stolen, but this can be mitigated using short-lived access tokens and refresh tokens.
• 🔄 **Refresh Tokens**: Refresh tokens allow for the issuance of new access tokens without requiring user re-authentication, balancing security and user experience.
• 🏢 **Use Case for Sessions**: Session-based authentication is suitable for applications needing instant session revocation or already using a centralized data store.
• 🌐 **Use Case for JWTs**: JWTs are ideal for stateless architectures, microservices, and scenarios where authentication data needs to be shared with other services.

Q & A

What are the two most common approaches to web authentication discussed in the script?

The two most common approaches to web authentication discussed in the script are session-based authentication and JSON Web Tokens (JWTs).

How does session-based authentication work?

In session-based authentication, the server verifies the user's login credentials, creates a new session if they're valid, stores session data, and sends back a unique session ID to the client, usually in a cookie. The client sends this session ID with each subsequent request, and the server uses it to look up session data for authentication.

What is the advantage of revoking a session in session-based authentication?

Revoking a session in session-based authentication is straightforward because the session data is stored on the server. The server can simply delete or invalidate the session at any time.

What challenges arise when using a centralized session store in a distributed system?

In a distributed system, all servers need access to the same session data, which typically requires a centralized session store like Redis or a distributed SQL database. This adds complexity and potential latency to each request as the server needs to make a separate trip to the session store.

How does JWT-based authentication differ from session-based authentication?

JWT-based authentication involves the server generating a token with a secret key after verifying the user's credentials. The client stores this token and sends it in the request headers for subsequent requests. The server verifies the token's signature and uses the data in the token for authentication, without storing any session state.

What are the common signing algorithms used for JWTs?

The common signing algorithms used for JWTs include HMAC, RSA, and ECDSA. HMAC is a symmetric signing method, while RSA and ECDSA are asymmetric methods offering more security by keeping the private key secret.

Why might HMAC be a concern from a security perspective?

HMAC might be a security concern because it requires sharing the secret key with any service that needs to verify the token. This can be a risk if the key is exposed or if the services are not trusted.

What is the purpose of refresh tokens in JWT-based authentication?

Refresh tokens are used in combination with short-lived access tokens to handle token expiration. When the access token expires, the client can send a refresh token to obtain a new access token without requiring the user to log in again, balancing security and user experience.

How does using JWTs benefit a microservices architecture?

JWTs are beneficial in a microservices architecture because they store all necessary data within the token itself, allowing services to verify and trust the token without needing to contact the authentication service on each request.

When should you choose session-based authentication over JWTs?

Session-based authentication is a better choice when you need the ability to revoke sessions instantly, if a user reports an account compromise, or when you already have a centralized data store for other purposes and can leverage it for session storage.

What considerations should be made when deciding between session-based and JWT-based authentication?

The decision between session-based and JWT-based authentication should consider the specific needs and architecture of your application, including the need for instant session revocation, the presence of a centralized data store, the requirement for a stateless architecture, and the need to share authentication data with other services.

Outlines

00:00

🔐 Session-Based Authentication Overview

This paragraph delves into the mechanics of session-based authentication, starting with the user submitting their login credentials to the server. Upon verification, the server initiates a session, storing session data in a database or in-memory cache like Redis. This data typically encompasses user ID, session expiration time, and other metadata. The server responds with a unique session ID, often delivered via a cookie. For subsequent requests, the client automatically sends this session ID, allowing the server to retrieve session data and authenticate the request. The advantage of session-based authentication is the ease of revoking sessions, but it requires a centralized session store in distributed systems, adding complexity and latency to requests.

05:02

🔑 JSON Web Tokens (JWT) Authentication Process

The second paragraph explains the flow of JWT-based authentication. The process begins similarly with the user submitting their login credentials, which the server verifies. If valid, the server generates a JWT signed with a secret key to ensure integrity and prevent tampering. The JWT contains all necessary data for authentication and is sent back to the client, often stored in local storage or a cookie. For subsequent requests, the client includes the JWT in the request headers, and the server uses it to authenticate and authorize the request without storing any session state. The paragraph also discusses the use of different signing algorithms for JWTs, including HMAC, RSA, and ECDSA, each with its own security implications and performance considerations. Additionally, it addresses the challenge of token expiration and the use of refresh tokens to enhance security and user experience by allowing short-lived access tokens and long-lived refresh tokens.

🏢 Choosing Between Session-Based and JWT Authentication

The final paragraph provides guidance on choosing between session-based and JWT authentication. Session-based authentication is recommended when the ability to instantly revoke sessions is necessary, such as in cases of compromised accounts, or when a centralized data store is already in place. It also highlights the security advantage of keeping sensitive data on the server. On the other hand, JWTs are preferred for stateless architecture, horizontal scaling across multiple servers, and sharing authentication data with other services, such as in a microservices architecture. The paragraph concludes with the suggestion to implement refresh tokens with JWTs to balance security and user experience, and it invites viewers to subscribe to a system design newsletter for further insights into large-scale system design.

Keywords

💡Web Authentication

Web authentication refers to the process of verifying the identity of a user or system in a web-based environment. It is crucial for securing access to sensitive data and services. In the video, two common approaches to web authentication are discussed: session-based authentication and JSON Web Tokens (JWTs), illustrating the importance of choosing the right method for different scenarios.

💡Session-Based Authentication

Session-based authentication is a method where the server creates a session for the user after verifying their credentials. The session data, which may include user ID and session expiration time, is stored on the server, and a unique session ID is sent to the client, typically in a cookie. This method is highlighted in the video as being straightforward for session revocation but adds complexity in distributed systems where a centralized session store is required.

💡JSON Web Tokens (JWTs)

JSON Web Tokens are a compact, URL-safe means of representing claims to be transferred between two parties. In the context of the video, JWTs are used for authentication by encoding user information and signing it with a secret key. The signed token is then sent to the client, which includes it in the headers of subsequent requests for authentication purposes. JWTs are contrasted with session-based authentication in terms of state management and scalability.

💡Session ID

A session ID is a unique identifier assigned by the server to a user's session. It is used as a key to retrieve session data stored on the server. In the script, the session ID is mentioned as being sent back to the client in the form of a cookie, which the client then automatically sends with each request to maintain the session.

💡Centralized Session Store

A centralized session store is a shared resource, such as Redis or a distributed SQL database, used to store session data in a distributed system. This is discussed in the video as a solution to enable multiple servers to access the same session data, which is necessary for session-based authentication but adds latency to each request.

💡Token Integrity

Token integrity refers to the assurance that the data within a token has not been altered since it was issued. In the video, the server generates JWTs with a secret key to ensure integrity, preventing tampering and ensuring that the data can be trusted for authentication.

💡Signing Algorithms

Signing algorithms are methods used to sign JWTs to ensure their integrity and authenticity. The video mentions HMAC, RSA, and ECDSA as common signing algorithms. HMAC is a symmetric method, while RSA and ECDSA are asymmetric, offering different security and efficiency trade-offs.

💡Refresh Tokens

Refresh tokens are used in conjunction with JWTs to handle token expiration securely. The video explains that a refresh token, which has a longer expiration time than the access token, can be used to obtain a new access token when the previous one expires, without requiring the user to re-authenticate.

💡Microservices Architecture

A microservices architecture is a style of software architecture where applications are composed of small, independent services that communicate over well-defined APIs. The video suggests that JWTs are particularly useful in such architectures because they allow services to authenticate and trust tokens without needing to contact an authentication service for each request.

💡Security vs. User Experience

The balance between security and user experience is a central theme in the video. It discusses how using short-lived access tokens in combination with refresh tokens can limit the window of potential misuse while still providing a seamless experience for the user, allowing them to remain authenticated over an extended period.

💡System Design

System design is the process of defining the architecture, components, modules, and data flow of a system. The video concludes by suggesting that understanding different authentication methods is part of broader system design considerations, which is also the focus of a recommended newsletter for readers interested in large-scale system design trends.

Highlights

Introduction to two common web authentication methods: session-based authentication and JSON Web Tokens (JWT).

Exploration of session-based authentication flow, involving server-side session data storage and session ID cookie exchange.

Advantages of session-based authentication include ease of session revocation and use of existing centralized data stores.

Challenges with session-based authentication in distributed systems, requiring access to shared session data.

JWT authentication flow explained, with server generating a token signed with a secret key after user credentials verification.

JWTs contain all necessary data for authentication, eliminating the need for server-side session storage.

Different signing algorithms for JWTs, including HMAC, RSA, and ECDSA, each with their own security and efficiency trade-offs.

HMAC's simplicity and efficiency contrasted with RSA and ECDSA's security advantages in asymmetric cryptography.

Handling JWT expiration with refresh tokens to balance security and user experience, using short-lived access tokens and longer-lived refresh tokens.

Refresh tokens are used to obtain new access tokens without user re-authentication, enhancing convenience.

When to use session-based authentication: instant session revocation needs and existing centralized data stores.

When to prefer JWTs: stateless architecture requirements and sharing authentication data across services in microservices.

Security considerations when choosing between session-based and JWT authentication methods.

Practical applications of JWTs in microservices architecture for seamless service-to-service authentication.

The importance of choosing the right signing algorithm based on security requirements and system architecture.

Recommendation to implement refresh tokens with JWTs to mitigate the risk of token theft and misuse.

Final thoughts on selecting the appropriate authentication method based on application needs and architecture.

Promotional mention of a system design newsletter for further insights into large-scale system design trends.

Transcripts

today we're diving into the world of web

authentication we'll explore the two

most common approaches session based

authentication and Json web tokens or

jots we'll walk through the flow of each

mechanism and discuss their pros and

cons by the end you'll have a clear

understanding of when to use each one

let's get started first let's walk

through the flow of session based

authentication the user send their login

credentials to the server the server

verifies these credentials if they're

valid it creates a new session the

server then stores the session data

typically in a database or in memory

cache like reddis this data may include

the user ID session exploration time and

other metadata the server sends back a

response with a unique session ID

usually in the form of a cookie on

subsequent requests the clients

automatically sends the session ID token

with each request the server takes the

session ID looks up the corresponding

session data in the session store and

uses that data to authenticate and

process a request the key point is that

with session based authentication the

server is responsible for creating and

storing the session data it then uses

the session ID as a key to retrieve this

data on future requests one advantage of

sessions is that revoking a session is

straightforward since the session data

is stored on the server the server can

simply delete or invalidate the session

at any time however in a distributed

system where your application runs on

multiple servers all those servers need

access to the same session data this is

typically achieved by using a

centralized session store that all

servers access like redis or a

distributor seal database while this

works well it does add some complexity

and potential incy to each request as

the server needs to make a separate trip

to the session store now let's look at

the flow of job based authentication

first the user sends their login

credentials to the server the server

verifies these credentials if they are

valid it generates a jot the server the

jot with a secret key this signature

ensures the Integrity of the token

preventing tempering the server then

sends back the jot to the client

typically in the response body the

client stores the jot usually in local

storage or a cookie on subsequent

request the client sends the jot in the

request headers the server verifies the

jot signature if it's valid the server

trust the data in the token and uses it

for authentication authorization the

critical difference here is that with

jots the server doesn't store any

session State all the necessary data is

contained within the token itself which

is stored on the client this makes jots

stainless for signing jots there are

several algorithms available with hmac

RSA and ecdsa being the most common hmag

is a symmetric signing method which

means that the same secret key is used

to sign and verify the token this is

simpler and more efficient but it

requires sharing the secret key with any

service that needs to verify the token

which can be a security concern RSA and

ecdsa on the other hand are asymmetric

signing methods they use a private key

to sign a token and a public key to

verify it this allows for a more secure

architecture where the private key is

kept secret and only is used for signing

while any service can verify the token

using the public key however this SM

complexity and computational overhead

compared to hmac the choice of signing

algorithms depends on your security

requirements and system architecture if

you have a monolithic application or

trust all the services in your system hm

might be sufficient but if you have a

microservices architecture or need to

share jots with untrusted thirdparty

Services RSA or ecdsa provide a more

secure Solution One Challenge with jots

is handling token expiration if a token

is stolen it can be used until it

expires to mitigate this you can use

refresh tokens in combination with

shortlived access tokens the access

token is the actual jot used for

authentication on each request it has a

short expiration time typically around

15 minutes the refresh token on the

other hand has a much longer expiration

time perhaps several days or weeks when

the access token expires instead of

requiring the user the login again the

client can send a refresh token to a

special token endpoint on the server the

server checks if the refresh token is

valid and hasn't been revoked if if

everything checks out the server issues

a new access token this process happens

behind the scenes without requiring

interaction from the user this approach

strikes a balance between security and

user experience the short lft access

token limit the window of potential

misuse if a token is stolen while the

Long Live refresh token allow users to

remain authenticated for an extended

period without needing to log in

repeatedly it's important to note that

the refresh token is only sent when the

access token has expired not on every

request the access token is sent on

every request that require

authentication so when should you use

session based authentication and when

adjust a better choice session based

authentication is a good fit when you

need the ability to revoke sessions

instantly if a user reports the account

is compromised you can immediately

invalidate the session on the server

side sessions are a good choice if you

already have a centralized data store

for other purposes in this case you can

leverage that existing infrastructure

for session storage as well however it's

important to keep in mind that using a

centralized session store does add some

latency to each request as the server

needs to fetch the session data from the

store finally sessions keep sensitive

data on the server which can be a

security advantage on the other hand JS

are a great choice when you need a stess

architecture because JS store all the

necessary data in the token itself your

server doesn't need to keep track of

sessions in memory or in a database this

makes it much easier to scale your

application horizontally across multiple

servers jots are also useful when you

need to share authentication data with

other services for instance in a

microservices architecture a jot

generated by a authentication Service

can be verified and trusted by other

services without needing to contact the

authentication Service on each request

if you do choose JS consider

implementing refresh tokens to balance

security and user experience refresh

token allows you to use shortlived

access token to limit the window of

potential misuse while still allowing

users to remain authenticated for an

extended period ultimately the choice

depends on the specific needs and

architecture of your

applications if you like our videos you

might like a system design newsletter as

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