Adding Debian Security Repository GPG key

Question

I'm kinda new when it comes to working with adding GPG keys. I am trying to use the debian security repository to the sources.list to further add security to my Pi but I am getting this error below. I have searched for an answer alost everywhere but cant find one. How do I add the GPG key for this repo?

Err:3 http://security.debian.org/debian-security buster/updates InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY AA8E81B4331F7F50 NO_PUBKEY 112695A0E562B32A
Reading package lists... Done
W: GPG error: http://security.debian.org/debian-security buster/updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY AA8E81B4331F7F50 NO_PUBKEY 112695A0E562B32A
E: The repository 'http://security.debian.org/debian-security buster/updates InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

Answer 1

Get the missing public keys from the Ubuntu keyserver and try if it helps:

rpi ~$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys AA8E81B4331F7F50 112695A0E562B32A
Executing: /tmp/apt-key-gpghome.YcaQxjGmfn/gpg.1.sh --keyserver keyserver.ubuntu.com --recv-keys AA8E81B4331F7F50 112695A0E562B32A
gpg: key 4DFAB270CAA96DFA: public key "Debian Security Archive Automatic Signing Key (10/buster) <[email protected]>" imported
gpg: key EDA0D2388AE22BA9: public key "Debian Security Archive Automatic Signing Key (9/stretch) <[email protected]>" imported
gpg: Total number processed: 2
gpg:               imported: 2