A Beginner's Guide to JWTs

Developer Blog Comments
1

A Beginner’s Guide to JWTs

What is a JWT? How are they used? Find out in this post!

2

Justin Walsh

Homebrew also allows one to easily install coreutils on Linux, and WSL2.
Making brew install coreutils available in most developers coding environments.

3

Riccardo10

Hi Brian,
Very nice introduction to JWTs.
One quick question, is it possible to programmatically revoke or delete a jwt after a user has signed out of an application? Or better still if there has been inactivity for a period of time?

Thanks.

4

Shane

The not before claim is abbreviated as nfb. It should be nbf

https://uploads.disquscdn.c…

5

Thanks! I’ll get it updated!

6

I tried following steps in Linux. Although, header and payload are not tampered, signature and output doesn’t match. What am I missing?

token="eyJhbGciOiJIUzI1NiJ9.eyJuYW1lIjoiSm9lIENvZGVyIn0.5dlp7GmziL2QS06sZgK4mtaqv0_xX4oFUuTDh1zHK4U"
signature=$(echo $token | cut -f 3 -d '.')
secret_key_in_hex=$(echo -n $signature'=' | basenc -d --base64url | hexdump -ve '/1 "%02x"')
headpay=$(echo $token | cut -f -2 -d '.')
echo -n $headpay | openssl dgst -sha256 -macopt hexkey:${secret_key_in_hex} -mac hmac -binary | basenc --base64url | sed 's/=//'