A public-key cryptosystem invented by Pascal Paillier in 1999.

The Paillier cryptosystem was invented in Pascal Paillier in 1999. It is a public-key cryptosystem which, due to its additive homomorphic property, is starting to be used in a number of research systems. It is semantically secure without modification unlike RSA which requires random padding to be semantically secure. It is based on the difficulty of computing n-th residue classes.