The client should provide you with a zip file (that includes IMOS-Raw.cer file, IMOS-Base64.cer ,IMOSFederationMetadata.xml file) or IMOS-Base64.cer file only.
Open the file with Notepad++
The certificate should automatically open.
To check the Valid To date of the certificate, use the following tool:
Copy and Paste the certificate in the Tool and click on Decode.
Check the Valid To date.