The HKAF publishes 2 metadata documents:
Metadata documents are prefereably accessible by https request but can be access via http.
All metadata documents are signed by the HKAF. Subscribers MUST use the public key available at https://md.hkaf.edu.hk/hkaf-metadata-certificate.pem to verify metadata documents whenever they are retrieved.
To confirm that you have obtained the correct key ensure the file you have downloaded conforms to the following:
$> openssl x509 -subject -dates -fingerprint -in hkaf-metadata-certificate.pem subject= /O=Hong Kong Access Federation/CN=HKAF Metadata notBefore=Oct 16 07:23:09 2017 GMT notAfter=Oct 14 07:23:09 2027 GMT SHA1 Fingerprint=B3:C0:57:D0:24:7F:21:27:A5:AF:9F:0D:0F:C5:AC:0F:29:6C:27:B3
The Joint Universities Computer Center Ltd is the federation registration authority for the Hong Kong Access Federation