Hiii

The signature that you provide in the AIIMS basic registration has to be your first name written in the running and not in block letter or initals. This signature will be used in the attendence sheet during the examination on exam day. It has nothing to do with you SSC certificate but yes it is better to use same signature so that there is no issue in identification later but remember if you have done the signature by just writng the initials in your SSC certificate then do not use same signature because Signatures having only Initials or done in CAPITAL letters are not acceptable in AIIMS registration.

Hope this helps.Incase of doubt please revert back freely.

Thanks!