Paillier cryptosystem

The Paillier cryptosystem, invented by and named after Pascal Paillier in 1999, is a probabilistic asymmetric algorithm for public key cryptography. The problem of computing ''n''-th residue classes is believed to be computationally difficult. The decisional composite residuosity assumption is the intractability hypothesis upon which this cryptosystem is based.

The scheme is an additive homomorphic cryptosystem; this means that, given only the public key and the encryption of $m\_1$ and $m\_2$, one can compute the encryption of $m\_1+m\_2$. Provided by Wikipedia