ElGamal Encryption

This crate provides additive homomorphic ElGamal encryption over jubjub curve and also supports fully no_std and parity-scale-codec.

Scheme

Alice has balance $a$ and public key $b$.
She generates the randomness $r$ and computes encrypted balance $(g^{r, g}a * b^{r)$.
When Bob transfers $c$ to Alice, he generates the randomness $r'$ and computes encrypted transfer amount $(g}{r'}, g^{c * b}{r'})$.
The sum of encrypted balance and transfer amount is folloing.

$$ (g^{r + r'}, g^{a + c} * b^{r + r'}) $$