Google API OAuth2 : “invalid_grant” error when requesting token for Service Account with Perl

Question

Got the credentials for Service Account from Developer Console

First, I converted p12 private key to PEM:

openssl pkcs12 -in 

        

Answer 1

Try to use BASE64URL instead of BASE64. JWT/JWS/JWE specifications use BASE64URL.

MIME::Base64 ---> MIME::Base64::URLSafe
encode_base64 ---> urlsafe_b64encode