Product:
Cognos Analytics 10.0.12 Framework Manager
Microsoft Windows 2012 server

Problem:
Error when importing certificate file to cognos keystore with IKEYMAN.EXE.

You have setup SSL to the IIS server for the Cognos gateway. To be able to connect with client tools you import certs to cognos keystore.

Go to folder C:\Program Files (x86)\ibm\cognos\model\jre\bin
Click on IKEYMAN.EXE to start the program
Open the certificate store file from folder C:\Program Files (x86)\ibm\cognos\model\configuration\certs
Enter the password
Click Import to import your certificate file
https://www.ibm.com/support/knowledgecenter/SSD29G_2.0.0/com.ibm.swg.ba.cognos.tm1_inst.2.0.0.doc/t_pa_use_ibmkeymgmt.html

Error message:
An IO exception has occurred
DER input, integer tag error

Solution:
The format of the certificate is wrong, please try a pfx file instead.

Error message:
An IO exception has occurred
invalid keystore format

Solution:
Wrong format selected when you open the file, please try PKSC12 instead.

More information:
https://www-01.ibm.com/support/docview.wss?uid=swg21339658