During registration of .SU domain names, registrar change, ownership transfer, or registration cancellation, as well as ID data change in the agreement, you will be required to submit to Rucenter:
You may check if you are identified in your personal account → Account → Contract section.
Copies of the requested documents could be submitted to Rucenter via:
Digital ID document copies can be submitted in .JPG, .PNG, .GIF, or .PDF formats. Attachment size should not exceed 10 MB.
In all cases you will be required to specify your contract number(s) or domain name(s).