cipher.CipherService.Cipher(ctx, orgID) now resolves, generates, and
caches DEKs per organization (Redis key decrypted_key:<orgID>).
Platform-level secrets keep the zero-UUID identity, renamed to
platformCipherID since it no longer partitions against user keys.
New encryptedkeys.Store interface with three impls:
postgres - backend default, durable via PG
dynamodb - existing AWS path, also covers Scylla Alternator via
AWS_ENDPOINT_URL_DYNAMODB
http - worker-side adapter that talks to the backend's new
/api/v1/internal/dek/:userID endpoint, so workers never
connect directly to Postgres
The HTTP endpoint sits behind a new InternalAuthMiddleware that does
constant-time bearer-token compare against INTERNAL_API_TOKEN. Fail-
closed if the env var is unset.
cipher.Service now takes an encryptedkeys.Store instead of a Dynamo
repository. The old internal/repository/dynamo_user_encrypted_keys.go
is deleted (the file also had a pre-existing copy-paste bug using
EmailMessageMapTable in Get/Del that's gone with it).
New migration 38 adds user_encrypted_keys (user_id PK, encrypted_data_key,
created_at, updated_at).
20 tests cover HTTP round-trip, conflict semantics, factory selection,
middleware auth (fail-closed / wrong-scheme / timing-safe / happy path),
and DEK handler responses through gin's test harness.
Matthew Meszaros