authentication

Description 🐜

If you only have a Credentials provider, you now are unable to get a CSRF token:

[next-auth][error][CALLBACK_CREDENTIALS_JWT_ERROR] 
https://next-auth.js.org/errors#callback_credentials_jwt_error Signin in with credentials only supported if JWT strategy is enabled UnsupportedStrategy [UnsupportedStrategyError]: Signin in with credentials only supported if JWT strategy is 

There was an error where someone was trying to sign up using the thirdparty recipe and postgres rejected the query cause of value too long for type character varying(128) - and in the thidparty table, only the third_party_user_id column has 128 chars limit.

Error log reference:

[https://app.zenhub.com/files/231921809/8968d6d6-bcdd-48d8-aa60-fd556e934acd/download](https://app.zenhub.com/files

Is your feature request related to a problem? Please describe.

The public key-based request signing functionality added to sso_proxy in buzzfeed/sso#106 is undocumented. In particular, it's not immediately obvious how to a) generate an appropriate keypair or b) validate a signed request in an upstream service.

Describe the solution you'd like

New documenta

Before opening, please confirm:

• I have installed the latest version of the Amplify CLI (see above), and confirmed that the issue still persists.
• I have searched for duplicate or closed issues.
• I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-cli/blob/master/CONTRIBUTI