The certificate for verifying the signature of the barcode printed on the Arrival Attestation document (valid since 11th October 2021) has the SHA-256 fingerprint:
41 3B F0 E8 78 EC FF 5C 60 F8 DD B9 4A B2 E1 26 E0 16 A6 C8 9E 00 14 DA C3 C0 3B 87 64 FA D9 93