Implement Jacobian coordinates

mratsim / constantine

Constantine: modular, high-performance, zero-dependency cryptography stack for verifiable computation, proof systems and blockchain protocols.

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Implement Jacobian coordinates #83

Closed mratsim closed 4 years ago

mratsim commented 4 years ago

Currently we only implement homogeneous projective coordinates.

However the complete formulae to defend against side-channel attacks may be more costly than masked select on Jacobian coordinates, especially on G2 for curves that have a costly non-residue or b in y² = x³ + b:

BN254_Snarks: -1 on 𝔽p, 9+𝑖 on 𝔽p²
BLS12_377: -5 on 𝔽p, 0+𝑖 on 𝔽p²

mratsim commented 4 years ago

Closed by #95