The questioner says: What if a person uses a damp cloth to wipe over his Khuffs, is this sufficient?
It’s sufficient; because he has applied water over the necessary area. Although, it’s better that he wipes over the socks directly using his hands, just as the Prophet ﷺ did. As for validity, then yes, it’s valid to do so.
Shaykh Muhammad ibn Hizaam – may Allaah preserve him
Abu Ishaq Muhammad Ibn Ahmad Ba Alawi