Failed to export portal public key file from keystore administration

I'm trying to get the portal public key file (verify.pse) to verify SAP Logon ticket for SSO.

I went through the systemAdmin->systemConfiguration->KeystoreAdministration->Download verify.pse file

I'm getting the .zip file, but encountering a format problem when trying to open the zip file.

Can someone help on this?

Thanks,

Nir