JWT - Payload detail

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swisskyrepo 2019-02-11 14:04:38 +01:00
parent bb0177916d
commit 88d5af0b19

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@ -15,10 +15,18 @@ JSON Web Token : `Base64(Header).Base64(Data).Base64(Signature)`
Example : `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkFtYXppbmcgSGF4eDByIiwiZXhwIjoiMTQ2NjI3MDcyMiIsImFkbWluIjp0cnVlfQ.UL9Pz5HbaMdZCV9cS9OcpccjrlkcmLovL2A2aiKiAOY`
Where we can split it into 3 components separated by a dot.
```powershell
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9 # header
eyJzdWIiOiIxMjM0[...]kbWluIjp0cnVlfQ # payload
UL9Pz5HbaMdZCV9cS9OcpccjrlkcmLovL2A2aiKiAOY # signature
```
### Header
Default algorithm is "HS256" (HMAC SHA256 symmetric encryption).
"RS256" is used for asymetric purposes (RSA asymmetric encryption and private key signature).
"RS256" is used for asymmetric purposes (RSA asymmetric encryption and private key signature).
```json
{
@ -38,6 +46,15 @@ Default algorithm is "HS256" (HMAC SHA256 symmetric encryption).
}
```
Claims are the predefined keys and their values:
- iss: issuer of the token
- exp: the expiration timestamp (reject tokens which have expired). Note: as defined in the spec, this must be in seconds.
- iat: The time the JWT was issued. Can be used to determine the age of the JWT
- nbf: "not before" is a future time when the token will become active.
- jti: unique identifier for the JWT. Used to prevent the JWT from being re-used or replayed.
- sub: subject of the token (rarely used)
- aud: audience of the token (also rarely used)
JWT Encoder Decoder: `http://jsonwebtoken.io`
## JWT Signature - None algorithm
@ -147,3 +164,4 @@ eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMj...Fh7HgQ:secret
- [Hacking JSON Web Tokens - From Zero To Hero Without Effort - Websecurify Blog](https://blog.websecurify.com/2017/02/hacking-json-web-tokens.html)
- [HITBGSEC CTF 2017 - Pasty (Web) - amon (j.heng)](https://nandynarwhals.org/hitbgsec2017-pasty/)
- [Critical vulnerabilities in JSON Web Token libraries - March 31, 2015 - Tim McLean](https://auth0.com/blog/critical-vulnerabilities-in-json-web-token-libraries//)
- [Learn how to use JSON Web Tokens (JWT) for Authentication - @dwylhq](https://github.com/dwyl/learn-json-web-tokens)