Does the signature method affect the expiration date of a Signed-URL in GCS?

Google Cloud Compute Infrastructure
1

I am creating a Signed-URL with GCS.
“signBlob” to sign a signature, it appears to expire in as little as 12 hours due to the rotation of the signBlob’s key.
doc: https://cloud.google.com/storage/docs/access-control/signed-urls?hl=en#signing-iam

So does this mean that even though the signature expires in 7 days, it could expire before that?

And if I want it to be valid for 7 days, do I have to use the HMAC key?

2

Reading this, signBlob is just one option for generating the signature. You can use other implementations of SHA-256 which do not depend on a key that rotates every 12 hours. So you should be able to use v4 signing with longer expirations if you don’t use signBlob.