---
# nuzlocke-tracker-t9aj
title: Migrate JWT verification from HS256 shared secret to asymmetric keys (JWKS)
<<<<<<< Updated upstream
status: todo
type: task
priority: low
created_at: 2026-03-21T11:14:29Z
updated_at: 2026-03-21T13:01:46Z
---

The backend currently verifies Supabase JWTs using an HS256 shared secret (`SUPABASE_JWT_SECRET`). Supabase recommends migrating to asymmetric keys (RS256) for better security.\n\nInstead of storing a shared secret, the backend would fetch public keys from Supabase's JWKS endpoint (`https://<project>.supabase.co/.well-known/jwks.json`) and verify tokens against those.\n\n## Changes needed\n\n- [ ] Update `backend/src/app/core/auth.py` to fetch and cache JWKS public keys\n- [ ] Change `jwt.decode` from `HS256` to `RS256` with the fetched public key\n- [ ] Remove `SUPABASE_JWT_SECRET` from config, docker-compose, deploy workflow, and .env files\n- [ ] Update tests\n\n## References\n\n- https://supabase.com/docs/guides/auth/signing-keys\n- https://supabase.com/docs/guides/auth/jwts
=======
status: completed
type: task
priority: low
created_at: 2026-03-21T11:14:29Z
updated_at: 2026-03-22T08:14:34Z
---

The backend currently verifies Supabase JWTs using an HS256 shared secret (`SUPABASE_JWT_SECRET`). Supabase recommends migrating to asymmetric keys (RS256) for better security.\n\nInstead of storing a shared secret, the backend would fetch public keys from Supabase's JWKS endpoint (`https://<project>.supabase.co/.well-known/jwks.json`) and verify tokens against those.\n\n## Changes needed\n\n- [x] Update `backend/src/app/core/auth.py` to fetch and cache JWKS public keys\n- [x] Change `jwt.decode` from `HS256` to `RS256` with the fetched public key\n- [x] Remove `SUPABASE_JWT_SECRET` from config, docker-compose, deploy workflow, and .env files\n- [x] Update tests\n\n## References\n\n- https://supabase.com/docs/guides/auth/signing-keys\n- https://supabase.com/docs/guides/auth/jwts


## Summary of Changes

Migrated JWT verification from HS256 shared secret to RS256 asymmetric key verification using JWKS:

- **auth.py**: Added `PyJWKClient` that fetches and caches public keys from Supabase's JWKS endpoint (`SUPABASE_URL/.well-known/jwks.json`). Keys are cached for 1 hour.
- **config.py**: Removed `supabase_jwt_secret` setting
- **pyproject.toml**: Changed `PyJWT` to `PyJWT[crypto]` for RS256 support
- **docker-compose.yml**: Configured local GoTrue for RS256 with mounted dev key
- **docker-compose.prod.yml**: Replaced `SUPABASE_JWT_SECRET` with `SUPABASE_URL`
- **deploy.yml**: Updated to pass `SUPABASE_URL` instead of `SUPABASE_JWT_SECRET`
- **tests**: Updated to use mocked JWKS client with RSA key pairs
>>>>>>> Stashed changes