I don't know anything about this area at all, but I remember in a cryptography lecture, being told you can perform arithmetic on un-padded standard RSA, is this similar to that. I imagine this could be very useful for banks possibly in databases, to for instance increase and decrease peoples funds, without standard employees seeing the total ammount of money in the account.
You might be thinking of blinding, which lets you do stuff like affix a signature to an encrypted message in such a way that the signature can be "moved" to the plaintext version of the message (I think that's how it went, anyway).
you can do that now with what's called a hidden accumulator - you add a secret random 20 digit # to the balance, let the employees do all the addition/subtraction they want, then subtract it again before you let the non-unclean at it.
