The additive homomorphism of Paillier’s encryption allows a set of participants (voters) to publish an encrypted value (ballot) and to compute the encrypted sum of all these values based on their ciphertext. Our scheme has the particularity that anyone can decrypt the sum, but only once all participants have contributed to its computation. More precisely, the sum can be decrypted at all times, but remains blinded until all participants have contributed their vote, which contains a share of the unblinding key.
See http://homepages.ulb.ac.be/jdossogn for publications regarding this encryption scheme.