About the validNotAfter value of the certificate SAPLogonTicketKeypair-cert

Question

I am configuring the SSO between the Enterprise Portal (NW04s based) and ECC 6.0 integrated ITS. During the SSO configuration we can specify a "valid to" date for the SAPLogonTicketKeypair. It will be stored in the certificate as the validNotAfter value.
As I can see in the “Key and Certificate Generation” screen, SAP only uses two digits to represent the year in the "valid to" field (e.g. 7/18/07 11:06AM). If I set the "valid to" date to 7/18/50, after creating the certificate, we can see that the validNotAfter date becomes 7/18/1950! If I set it to 7/18/49, then it will be 7/18/2049.
Yes, we can set four digits (e.g. 7/18/2099) for the field "valid to" when creating the logon ticket key pair. And the certificate will be created with validNotAfter time with 2099. But actually, if I import the certificate to ECC system via transaction STRUSTSSO2, the SSO does not work.
I did some test with the value of the "valid to", and verified the SSO between Portal and ECC integrated ITS. Here are the results:
Valid To: 7/18/28
SSO result: successful
Valid To: 7/18/2099
SSO result: failed
Valid To: 12/31/49
SSO result: failed
Valid To: 7/18/28  (I set the date/time back to the same with the first test in order to confirm that the SSO is still working)
SSO result: successful
My question is that what's the last date for the validNotAfter value in the SAPLogonTicketKeypair certificate which supports the SSO? According to my test results, it should be a date between 2028 and 2049.

Answer 1

I have got the answer for my question. SAP Note 550742 and 499386 mentioned the year. Self-signed certificates are generated with longer validity periods (up to the year 2038).