# Jwt.io debugger and ESxxx validation

**URL:** <https://community.auth0.com/t/jwt-io-debugger-and-esxxx-validation/41716>\
**Category:** JWT.io\
**Tags:** debugger\
**Created:** [April 24, 2020, 4:02pm UTC](https://community.auth0.com/t/jwt-io-debugger-and-esxxx-validation/41716 "2020-04-24T16:02:40Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![fxmathieu](https://sea1.discourse-cdn.com/auth0/user_avatar/community.auth0.com/fxmathieu/32/20730_2.png) [@fxmathieu](https://community.auth0.com/u/fxmathieu)\
**Post date:** [April 24, 2020, 4:02pm UTC](https://community.auth0.com/t/jwt-io-debugger-and-esxxx-validation/41716/1 "2020-04-24T16:02:40Z")

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Hi,

Just a question about validation of signature token using ESS algorithm.

Is it normal to reject a signature made with a certificate of a different ECDSA while standard Java signature verification allow it ?

In other words [jwt.io](http://jwt.io) debugger says:  
ESS256 is ok with certificat ECDSA-256 but ko with ECDSA-384 or ECDSA-512  
ESS384 is ok with certificat ECDSA-384 but ko with ECDSA-256 or ECDSA-512  
ESS512 is ok with certificat ECDSA-512 but ko with ECDSA-256 or ECDSA-384

Thanks for your explanation  
François