There's a range of algorithms that support homomorphism.<p><a href="https://en.m.wikipedia.org/wiki/ElGamal_encryption" rel="nofollow">https://en.m.wikipedia.org/wiki/ElGamal_encryption</a><p>ElGamal is very simple and supports multiplicative homomorphism. If you do it over an elliptic curve, this changes to additive.<p>Another is NTRU, but it's naturally addictively homomorphic.<p><a href="https://en.wikipedia.org/wiki/NTRUEncrypt" rel="nofollow">https://en.wikipedia.org/wiki/NTRUEncrypt</a><p>The values are added modulus 3 though so I'm not aware of any applications for it.<p>For example, adding cipher texts of the plaintexts [1,2,0,0] and [1,1,0,1] results in [2,0,0,1]