https://github.com/engineering87/jwt-inspector
Effortlessly decode, inspect, and validate JWTs
https://github.com/engineering87/jwt-inspector
decoding dotnet jsonwebtoken jwt security token validation
Last synced: 12 months ago
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Effortlessly decode, inspect, and validate JWTs
- Host: GitHub
- URL: https://github.com/engineering87/jwt-inspector
- Owner: engineering87
- License: mit
- Created: 2024-11-06T10:29:57.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2025-04-09T22:30:01.000Z (12 months ago)
- Last Synced: 2025-04-09T23:28:25.261Z (12 months ago)
- Topics: decoding, dotnet, jsonwebtoken, jwt, security, token, validation
- Language: C#
- Homepage:
- Size: 85 KB
- Stars: 2
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# JwtInspector - A Library for Decoding and Validating JWT Tokens
[](https://opensource.org/licenses/MIT)
[](https://github.com/engineering87/jwt-inspector/issues)
[](https://www.nuget.org/packages/JwtInspector.Core)
[](https://github.com/engineering87/jwt-inspector/actions/workflows/dotnet.yml)
[](https://github.com/engineering87/jwt-inspector)
JwtInspector is a C# library that provides utilities for decoding, validating, and inspecting JWT (JSON Web Tokens). This library simplifies working with JWTs by providing easy-to-use methods for extracting data, validating tokens, and more.
The library supports various use cases, such as decoding JWT payloads, validating token expiration, and verifying the authenticity of tokens using HMAC-SHA algorithms.
## Features
- Decode JWT tokens to extract claims and payload.
- Validate JWT token authenticity and expiration.
- Support for handling `iat` (issued at), `exp` (expiration), and `sub` (subject) claims.
- Provides a simple interface for inspecting JWT headers, payloads, and signatures.
- Easy-to-use methods for handling base64 URL encoding and decoding.
- JWT validation against a symmetric key (HMAC-SHA256) and token verification.
## Installation
You can install the library via the NuGet package manager with the following command:
```bash
dotnet add package JwtInspector.Core
```
## Usage
### Decoding JWT Payload
To decode the payload of a JWT token and get a dictionary of claims:
```csharp
using JwtInspector.Core.Services;
var jwtInspector = new JwtInspectorService();
string token = "";
var claims = jwtInspector.DecodePayloadAsJson(token);
Console.WriteLine(claims);
```
### Validating JWT Token
To validate a JWT token using a secret key:
```csharp
using JwtInspector.Core.Services;
var jwtInspector = new JwtInspectorService();
string token = "";
string secretKey = "";
bool isValid = jwtInspector.ValidateToken(token, secretKey);
Console.WriteLine($"Token valid: {isValid}");
```
### Extracting JWT Parts
You can extract the header, payload, and signature from a JWT token:
```csharp
using JwtInspector.Core.Services;
var jwtInspector = new JwtInspectorService();
string token = "";
var (header, payload, signature) = jwtInspector.ExtractJwtParts(token);
Console.WriteLine($"Header: {header}");
Console.WriteLine($"Payload: {payload}");
Console.WriteLine($"Signature: {signature}");
```
### Checking Token Expiration
To check if a JWT token is expired:
```csharp
using JwtInspector.Core.Services;
var jwtInspector = new JwtInspectorService();
string token = "";
bool isExpired = jwtInspector.IsExpired(token);
Console.WriteLine($"Token expired: {isExpired}");
```
### Extracting JWT Claims
To get the claims from a JWT token:
```csharp
using JwtInspector.Core.Services;
var jwtInspector = new JwtInspectorService();
string token = "";
var claims = jwtInspector.GetClaims(token);
foreach (var claim in claims)
{
Console.WriteLine($"{claim.Key}: {claim.Value}");
}
```
### Example Usage: Validating a Token with HMAC-SHA256
```csharp
using JwtInspector.Core.Services;
using Microsoft.IdentityModel.Tokens;
var jwtInspector = new JwtInspectorService();
string secretKey = "my_secret_key_123456789123456789"; // 32 bytes key
string token = "";
bool isValid = jwtInspector.ValidateToken(token, secretKey);
Console.WriteLine($"Is token valid: {isValid}");
```
## Methods Overview
### Decoding methods
- `DecodeBase64Url(string input)`: Decodes a Base64Url encoded string.
- `DecodePayload(string token)`: Decodes the payload of a JWT token.
- `DecodePayloadAsJson(string token)`: Returns the decoded JWT payload as a JSON string.
- `ExtractJwtParts(string token)`: Extracts the header, payload, and signature from a JWT token.
- `GetAudience(string token)`: Extracts the audience (`aud`) from the JWT token.
- `GetClaims(string token)`: Extracts all claims from the JWT token.
- `GetExpirationDate(string token)`: Extracts the expiration date (`exp`) of the JWT token.
- `GetIssuedAt(string token)`: Extracts the issued date (`iat`) of the JWT token.
- `GetJwtId(string token)`: Extracts the JWT ID (`jti`) of the JWT token.
- `GetSigningAlgorithm(string token)`: Extracts the signing algorithm used in the JWT.
- `IsExpired(string token)`: Checks if the JWT token is expired.
- `IsValidFormat(string token)`: Checks if the JWT token has a valid format (three parts separated by dots).
- `GetIssuer(string token)`: Retrieves the issuer claim from the JWT token.
- `GetCustomClaim(string token, string claimKey)`: Retrieves a specific custom claim from the JWT token.
- `IDictionary GetAllHeaders(string token)`: Retrieves all headers from the JWT token.
- `DecodePayloadAs(string token)`: Deserializes the JWT payload into a strongly-typed object.
- `GetTokenSummary(string token)`: Generates a human-readable summary of the JWT token contents.
### Validation methods
- `ValidateToken(string token, string secretKey)`: Validates the JWT token using the provided secret key for HMAC-SHA256 verification.
- `VerifyIssuer(string token, string expectedIssuer)`: Verifies that the issuer of the token matches the expected issuer.
- `ValidateIssuerAndAudience(string token, string expectedIssuer, string expectedAudience)`: Verifies that the issuer and audience of the token match the expected values.
- `ValidateLifetime(string token)`: Validates the token's lifetime based on the expiration date.
- `ValidateAlgorithm(string token, string expectedAlgorithm)`: Verifies that the algorithm used to sign the token matches the expected algorithm.
- `ValidateIssuerSigningKey(string token, string signingKey)`: Ensures that the token was signed using the correct signing key.
- `ValidateClaims(string token, IDictionary requiredClaims)`: Validates specific claims in the token (e.g., roles, permissions).
- `ValidateNotBefore(string token)`: Validates that the token is not used before the specified 'Not Before' time (nbf claim).
## JWT Format
A valid JWT token consists of three parts:
- **Header**: Contains metadata such as the signing algorithm (`alg`) and token type (`typ`).
- **Payload**: Contains the claims, which can be public, private, or registered claims such as `sub`, `iat`, `exp`, `aud`.
- **Signature**: A cryptographic signature used to verify the integrity of the token.
A JWT token is typically represented in the following format: `header.payload.signature`
## Example JWT
A typical JWT might look like this:
`eyJhbGciOiAiSFMyNTYiLCAidHlwIjogIkpXVCJ9.eyJzdWIiOiAiMTIzNDU2Nzg5MCIsICJuYW1lIjogIkpvaG4gRG9lIiwgImlhdCI6IDE1MTYyMzkwMjJ9.MD8fpgF7N0XWhQGGVm9lA_EvVoHkcmrr74xhL2y7H3U`
## Contributing
Thank you for considering to help out with the source code!
If you'd like to contribute, please fork, fix, commit and send a pull request for the maintainers to review and merge into the main code base.
* [Setting up Git](https://docs.github.com/en/get-started/getting-started-with-git/set-up-git)
* [Fork the repository](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/fork-a-repo)
* [Open an issue](https://github.com/engineering87/jwt-inspector/issues) if you encounter a bug or have a suggestion for improvements/features
## Licensee
JwtInspector source code is available under MIT License, see license in the source.
## Contact
Please contact at francesco.delre.87[at]gmail.com for any details.