Ella

Posted on Mar 21

JWT vs. PASETO: Which One is Right for You?

#webdev #security #architecture #jwt

Introduction

If you work with authentication in web applications, you’ve probably used JSON Web Tokens (JWT). JWT is a widely adopted standard, but it has its complexities and potential security pitfalls.

As an alternative, PASETO (Platform-Agnostic Security Tokens) has emerged, designed to simplify secure token usage while enforcing strong cryptographic defaults. PASETO aims to reduce the cognitive load involved in securing tokens by removing many of the configuration steps that JWT requires.

But dose the promise of enhanced security and simplicity mean it’s time to switch from JWT to PASETO?

In this post, we’ll break down the key differences between JWT and PASETO, discuss their strengths and weaknesses, and give you some things to think about before deciding if a switch is right for your project.

How JWT Works and Its Common Pitfalls

1. JWT Offers Flexibility, But at a Cost

JWT supports multiple algorithms, giving developers the option to choose between HMAC, RSA, and ECDSA for signing and encryption. This flexibility, while useful, also introduces risks:

Algorithm Confusion Attacks: If a developer mistakenly sets the algorithm to 'none', signature verification is skipped entirely.
Key Management Complexity: Handling private/public key pairs securely requires extra effort, increasing the risk of misconfiguration.

2. JWT Payloads Are Not Encrypted By Default

JWT uses Base64 URL-safe encoding for the payload, but this is not encryption—it is simply an encoding method. This means that unless explicitly encrypted (e.g., via JWE - JSON Web Encryption), the payload remains readable.

Problem: Even if a token is signed, anyone intercepting it can see its contents.
Workaround: Developers must implement additional encryption, adding complexity.

3. Verification Requires Extra Implementation

With JWT, servers need to:

✅ Validate the token’s signature

✅ Check expiration time (exp)

✅ Ensure the correct algorithm is used

This extra verification code opens the door for potential mistakes, which could compromise security.

How PASETO Differs from JWT

1. Fixed Cryptographic Algorithms

Unlike JWT, which allows multiple cryptographic options, PASETO enforces secure defaults for each version:

V2 (widely used)

✅ Ed25519 for signing (public-key cryptography)
✅ XChaCha20-Poly1305 for encryption (symmetric encryption)

By removing algorithm flexibility, PASETO prevents misconfigurations like weak signing algorithms or 'none' attacks'.

2. No Algorithm Confusion Attacks

PASETO eliminates algorithm confusion attacks by not storing cryptographic details in the token itself. Unlike UWT, which includes the algorithm in the header, PASETO predefines the cryptographic method for each version, ensuring security.

JWT Example:
```
{
  "alg": "RS256",
  "typ": "JWT"
}
```
Attackers can tamper with this and attempt downgrade attacks.
PASETO Solution:

✅ The cryptographic method is predefined based on the version, eliminating this risk.

3. Built-in Support for Encryption

PASETO supports both:

🔹 Public-key signed tokens (public) → Like JWT's JWS

🔹 Symmetric encrypted tokens (local) → Like JWT's JWE, but simpler

This means sensitive data can be protected more easily without requiring extra encryption layers.

When JWT Might Still Be a Better Choice

1. Compatibility with Existing Systems

JWT is the default choice for:

✅ OAuth 2.0 and OpenID Connect (OIDC)

✅ Authentication providers (Auth0, Firebase, AWS Cognito)

✅ Many frameworks and libraries

Switching to PASETO might require rewriting authentication logic or customizing integrations, which could introduce significant overhead.

2. Larger Ecosystem and Community Support

JWT has been around longer, meaning:

✔ More libraries and tools exist across programming languages

✔ More third-party services natively support it

PASETO is growing, but its adoption is still limited compared to JWT, meaning it may not yet have the same breadth of community and ecosystem support.

3. Not All Applications Need PASETO’s Features

If your system already encrypts sensitive data before placing it in JWT, and you follow best practices for validation and key management, JWT can still be a secure option.

JWT vs PASETO: Key Differences at a Glance

Feature	JWT	PASETO
Cryptographic Flexibility	Multiple algorithms (HMAC, RSA, ECDSA)	Fixed algorithms (Ed25519, XChaCha20)
Algorithm Confusion Attacks	Possible (due to algorithm in the header)	Not possible (predefined in version)
Encryption Support	Not built-in, requires extra implementation	Built-in support for both public-key and symmetric encryption
Complexity of Key Management	Higher (public/private keys)	Simplified (secure defaults)
Ecosystem Support	Large, mature ecosystem	Smaller, growing community

Conclusion: Should You Switch to PASETO?

It depends.

If stronger security with minimal configuration is your priority, PASETO offers clear advantages over JWT by:

✅ Eliminating weak algorithm choices

✅ Preventing algorithm confusion attacks

✅ Providing built-in encryption

However, if your application relies on JWT-based authentication frameworks, migrating may introduce challenges such as:

❌ Rewriting existing authentication flows

❌ Limited third-party support

Ultimately, PASETO is not a direct replacement for JWT, but rather an alternative designed to reduce common security pitfalls. Carefully consider your project’s security needs, infrastructure, and compatibility before making the switch.

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