Why is JWT popular?
Summary
TLDRIn this video, Sahn, co-author of system design interview books, explains the power and risks of JSON Web Tokens (JWTs) in web security. JWTs are widely used for secure information transmission between parties, utilizing a three-part structure: header, payload, and signature. The video covers signing algorithms, claims, and best practices for secure implementation. It also highlights potential vulnerabilities, such as token hijacking and cryptographic weaknesses. While JWTs offer portability and scalability, they can pose risks if not used carefully. Key security tips and JWT use cases in authentication and authorization are discussed.
Takeaways
- 🔒 JSON Web Tokens (JWTs) securely transmit identity over the web, but a stolen JWT can give hackers full access.
- 🧑💻 JWTs consist of three parts: the header, payload, and signature, each base64 encoded and separated by a period.
- 📋 The payload stores claims, which are statements about a user or entity. Claims can be registered, public, or private.
- 🔐 JWTs are usually signed, not encrypted, meaning that while the data is encoded, it can still be read if intercepted.
- 🛡️ There are two main signing algorithms: symmetric (HMAC SHA256) and asymmetric (RSA), each with different security trade-offs.
- 🚫 JWT payloads should never contain sensitive information unless encrypted, as they are not encrypted by default.
- ⏳ JWTs are stateless and not ideal for managing user sessions, as revoking tokens can be difficult.
- ⚠️ Common JWT vulnerabilities include token hijacking and weak cryptographic algorithms, which can be exploited.
- ✔️ Best practices for JWTs include keeping payloads small, using short expiration times, and securing tokens properly.
- 📈 JWTs offer scalability for authentication and authorization, but they can be vulnerable if not implemented securely.
Q & A
What is a JSON Web Token (JWT)?
-A JSON Web Token (JWT) is a secure method for transmitting information between parties as JSON objects. It is widely used in web security for its ability to securely authenticate and authorize users.
How is a JWT structured?
-A JWT consists of three parts: the header, the payload, and the signature. Each part is base64 encoded and separated by a period.
What information is typically included in the JWT header?
-The JWT header usually contains the token type (JWT) and the algorithm used for signing, such as HMAC SHA256 or RSA.
What is the purpose of the JWT payload?
-The payload of a JWT contains claims, which are statements about an entity (usually the user) along with additional data. Claims can be registered, public, or private.
Why should sensitive information not be included in a JWT payload?
-Since JWTs are usually only signed and not encrypted, the payload can be read if intercepted. Therefore, sensitive information should not be included unless the payload is encrypted.
What are the two main types of JWT signing algorithms?
-JWTs can be signed using symmetric algorithms, like HMAC SHA256, which use a shared secret key for both signing and verification. Alternatively, they can use asymmetric algorithms, like RSA, which use a public/private key pair.
What are some of the key advantages of using JWTs?
-JWTs are self-contained and portable, making them useful for secure information exchange without requiring server-side storage. They are commonly used for authentication and authorization in standards like OAuth2 and OpenID Connect.
What are some of the key risks and vulnerabilities associated with JWTs?
-JWTs can be vulnerable to token hijacking, where attackers steal a JWT to impersonate a user. They can also be exposed to cryptographic weaknesses, especially if weak hashing algorithms are used.
What are some best practices for securely using JWTs?
-Best practices include keeping JWT payloads compact, using short expiration times, storing tokens securely, invalidating leaked tokens, and using strong signature algorithms.
When should JWTs not be used?
-JWTs should not be used when handling highly sensitive data unless encryption is applied. They are also not ideal for managing user sessions due to their stateless nature, making session revocation difficult.
Outlines
🔐 Understanding the Basics of JSON Web Tokens (JWTs)
This paragraph introduces JSON Web Tokens (JWTs) as a secure method for transmitting information across the web. The analogy of losing a passport illustrates the risk of a stolen JWT, which grants full access to the hacker. It explains that the video will cover both the benefits and the risks of using JWTs. JWTs are defined as a way to securely transmit data between parties, formatted as JSON objects. The structure of a JWT is broken down into three parts: the header, payload, and signature, all base64 encoded and separated by periods. The header usually includes the token type (JWT) and the algorithm used (HMAC SHA256 or RSA). The payload contains claims, which describe information about the user or entity. JWTs are mostly signed but not encrypted, so sensitive data should not be stored unless first encrypted. JWTs provide a scalable and portable way to handle authentication and authorization, but users must be aware of potential vulnerabilities.
📜 JWT Structure and Signing Algorithms Explained
This paragraph delves deeper into the structure and signing mechanisms of JWTs. The payload of the JWT contains claims, which are statements about the user or entity and can include registered, public, or private claims. It emphasizes that while the payload is encoded, it is not encrypted, meaning it can be read if intercepted. The section then explains how JWTs are signed to ensure data integrity, with two main types of signing algorithms: symmetric (HMAC SHA256) and asymmetric (RSA). Symmetric algorithms use a shared secret key, while asymmetric ones use a public/private key pair. The benefits and drawbacks of each algorithm are also discussed, highlighting the importance of choosing the right one based on the application needs.
⚠️ JWT Risks and Vulnerabilities
Here, the focus is on potential risks and common vulnerabilities associated with JWTs. Token hijacking is a key issue, where attackers steal a valid JWT to impersonate the user. JWTs can also be vulnerable to weak cryptographic algorithms, making them susceptible to brute force attacks. It emphasizes the importance of strong security practices, such as using secure signing algorithms and limiting token expiration times. Additionally, the paragraph points out that JWTs are not ideal for managing user sessions because they are stateless, making it challenging to revoke access after issuance.
💡 Best Practices for Securing JWTs
This paragraph provides practical advice for securing JWTs. It recommends minimizing the payload to only include necessary claims, using short expiration times for tokens, securely storing tokens, and ensuring any leaked tokens are invalidated. It also stresses the importance of using strong signing algorithms to protect against token forgery or tampering. Following these best practices can help mitigate the risks associated with using JWTs in web applications.
👍 Pros and Cons of JWTs
The pros and cons of using JWTs are weighed in this paragraph. On the positive side, JWTs are self-contained, portable, and do not require server-side storage, making them highly scalable. However, the drawbacks include vulnerability to theft if intercepted and performance issues if too much information is stored in the payload, making the token large. The section concludes by reinforcing that while JWTs offer a scalable solution for authentication and authorization, they must be implemented carefully to avoid potential security risks.
📩 Subscribe to the System Design Newsletter
This final paragraph encourages viewers to subscribe to the System Design newsletter from ByteByteGo, which covers trending topics in large-scale system design. It highlights that the newsletter is trusted by over 500,000 readers and directs viewers to subscribe via their blog.
Mindmap
Keywords
💡JSON Web Token (JWT)
💡Payload
💡Header
💡Signature
💡Symmetric Algorithm
💡Asymmetric Algorithm
💡Claims
💡Token Hijacking
💡Token Expiration
💡OAuth2
Highlights
JSON Web Tokens (JWTs) allow secure identity transmission across the web, but a stolen JWT can give hackers full access.
JWTs consist of three parts: the header, payload, and signature, all of which are base64 encoded and separated by periods.
The header typically contains the token type (JWT) and the algorithm used, such as HMAC SHA256 or RSA.
JWT payloads store claims, which can be registered, public, or private, with predefined claims like issuer, expiration time, and subject.
While JWTs can be encrypted using JSON Web Encryption (JWE), most are signed but not encrypted, meaning the data is visible if intercepted.
JWTs should not carry sensitive information unless encrypted, as the data is easily accessible in transit.
Symmetric algorithms like HMAC SHA256 use a shared secret key, while asymmetric algorithms like RSA use a public/private key pair for signing.
JWTs are often used in OAuth2 and OpenID Connect for authentication and authorization.
JWTs are not suitable for managing user sessions as they are stateless, and revoking JWT access is difficult.
Common vulnerabilities include token hijacking, where an attacker steals a valid JWT, and cryptographic weaknesses, particularly when weak hashing algorithms are used.
To mitigate risks, use short expiration times, store tokens securely, invalidate leaked tokens, and use strong signature algorithms.
JWTs are self-contained and portable, eliminating the need for server-side storage.
If a JWT is intercepted, it can provide full access to resources, as the payload is not encrypted by default.
Large JWT payloads can negatively impact performance, especially if too much data is included.
Overall, JWTs offer a scalable solution for authentication and authorization if implemented with caution and best practices.
Transcripts
JSON Web Tokens let your identity travel the web securely.
But like losing your passport, a stolen JWT gives hackers full access.
In this video, we'll unlock the immense potential of JWTs, and the dangers lurking within.
I'm Sahn, co-author of best-selling system design interview books. We explain
complex system design concepts clearly through animations. Let's get started.
JSON Web Tokens, commonly known as JWTs,
are a robust method for securely transmitting information between parties as JSON objects.
They have become a cornerstone in the world of web security for good reasons.
First, let's talk about JSON itself. It's a lightweight data interchange
format that's easy to read and write for humans and simple for machines to parse and generate.
It's the backbone of JWTs because it represents its payload,
which is where you store the data you want to transmit.
Now, JWTs have a structure of three parts: the header,
the payload, and the signature. Each section is base64 encoded and separated by a period.
The header typically consists of the token type,
which is JWT, and the algorithm being used, like HMAC SHA256 or RSA.
The payload of a JWT is where you store the claims.
Claims are statements about an entity, which is typically the
user with some additional data. There are three types of claims: registered, public,
and private. Registered claims are predefined, like the issuer, expiration time, and subject.
While JWT payloads can be encrypted using JSON Web
Encryption (JWE), most implementations use signed but not encrypted tokens.
This means that while the data is encoded, it is not encrypted and can be read if intercepted.
That’s why sensitive information should
never travel in a JWT payload unless it's encrypted first.
Let's talk about signing these tokens.
Signing is like sealing an envelope with a wax stamp to ensure it hasn't been tampered with.
There are two main types of signing algorithms:
Symmetric algorithms, like HMAC SHA256,
use a shared secret key for both signing and verification.
Asymmetric algorithms, such as RSA, use a public/private key pair where
the private key signs the token and the public key verifies it.
When choosing an algorithm, consider your needs. Symmetric keys are quick
and simple but the secret key must be shared between parties ahead of time.
Asymmetric keys allow verification of the creator without sharing private keys but are slower.
Signed JWTs provide authentication, authorization, and secure information exchange. Upon login,
the server creates a signed JWT with user details and sends it back. The client uses
this to access protected resources by sending the token in the HTTP header.
JWTs are commonly used in standards
like OAuth2 and OpenID Connect for authentication and authorization.
However, it's crucial to know when not to use JWTs. The payload is
not encrypted by default so should not contain highly sensitive data.
Also, JWTs aren't ideal for managing user sessions
since they are stateless. Revoking JWT access can be challenging.
Some common vulnerabilities to be aware of include token hijacking,
where an attacker steals a valid JWT to impersonate a user.
JWTs also could be vulnerable to cryptographic weaknesses if using
weak hashing algorithms. Automated brute force attacks may try to crack token signatures.
To mitigate risks when using JWTs, some best practices to follow are: keeping JWT payloads
compact with only the necessary user claims; using short token expiration times when possible;
storing tokens securely and invalidating any leaked tokens; and using strong signature
algorithms .
The pros are clear: JWTs are self-contained, portable,
and don’t require server-side storage. On the downside, JWTs can be vulnerable to theft,
and if intercepted, can provide full access to resources. The payload can
also get quite large if too much information is included, which can affect performance.
Overall, JWTs provide a scalable way to handle authentication, authorization,
and information exchange if implemented carefully.
If you like our videos, you might like our System Design newsletter, as well.
It covers topics in trends and large-scale system design.
Trusted by 500,000 readers.
Subscribe at blog.bytebytego.com.
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