/* Sonobe's Nova + CycleFold decider verifier. Joint effort by 0xPARC & PSE. More details at https://github.com/privacy-scaling-explorations/sonobe Usage and design documentation at https://privacy-scaling-explorations.github.io/sonobe-docs/ Uses the https://github.com/iden3/snarkjs/blob/master/templates/verifier_groth16.sol.ejs Groth16 verifier implementation and a KZG10 Solidity template adapted from https://github.com/weijiekoh/libkzg. Additionally we implement the NovaDecider contract, which combines the Groth16 and KZG10 verifiers to verify the zkSNARK proofs coming from Nova+CycleFold folding. */ /* =============================== */ /* KZG10 verifier methods */ {{ kzg10_verifier }} /* =============================== */ /* Groth16 verifier methods */ {{ groth16_verifier }} /* =============================== */ /* Nova+CycleFold Decider verifier */ /** * @notice Computes the decomposition of a `uint256` into num_limbs limbs of bits_per_limb bits each. * @dev Compatible with sonobe::folding-schemes::folding::circuits::nonnative::nonnative_field_to_field_elements. */ library LimbsDecomposition { function decompose(uint256 x) internal pure returns (uint256[{{num_limbs}}] memory) { uint256[{{num_limbs}}] memory limbs; for (uint8 i = 0; i < {{num_limbs}}; i++) { limbs[i] = (x >> ({{bits_per_limb}} * i)) & ((1 << {{bits_per_limb}}) - 1); } return limbs; } } /** * @author PSE & 0xPARC * @title NovaDecider contract, for verifying Nova IVC SNARK proofs. * @dev This is an askama template which, when templated, features a Groth16 and KZG10 verifiers from which this contract inherits. */ contract NovaDecider is Groth16Verifier, KZG10Verifier { /** * @notice Computes the linear combination of a and b with r as the coefficient. * @dev All ops are done mod the BN254 scalar field prime */ function rlc(uint256 a, uint256 r, uint256 b) internal pure returns (uint256 result) { assembly { result := addmod(a, mulmod(r, b, BN254_SCALAR_FIELD), BN254_SCALAR_FIELD) } } /** * @notice Verifies a nova cyclefold proof consisting of two KZG proofs and of a groth16 proof. * @dev The selector of this function is "dynamic", since it depends on `z_len`. */ function verifyNovaProof( // inputs are grouped to prevent errors due stack too deep uint256[{{ 1 + z_len * 2 }}] calldata i_z0_zi, // [i, z0, zi] where |z0| == |zi| uint256[4] calldata U_i_cmW_U_i_cmE, // [U_i_cmW[2], U_i_cmE[2]] uint256[2] calldata u_i_cmW, // [u_i_cmW[2]] uint256[3] calldata cmT_r, // [cmT[2], r] uint256[2] calldata pA, // groth16 uint256[2][2] calldata pB, // groth16 uint256[2] calldata pC, // groth16 uint256[4] calldata challenge_W_challenge_E_kzg_evals, // [challenge_W, challenge_E, eval_W, eval_E] uint256[2][2] calldata kzg_proof // [proof_W, proof_E] ) public view returns (bool) { require(i_z0_zi[0] >= 2, "Folding: the number of folded steps should be at least 2"); // from gamma_abc_len, we subtract 1. uint256[{{ public_inputs_len - 1 }}] memory public_inputs; public_inputs[0] = {{pp_hash}}; public_inputs[1] = i_z0_zi[0]; for (uint i = 0; i < {{ z_len * 2 }}; i++) { public_inputs[2 + i] = i_z0_zi[1 + i]; } { // U_i.cmW + r * u_i.cmW uint256[2] memory mulScalarPoint = super.mulScalar([u_i_cmW[0], u_i_cmW[1]], cmT_r[2]); uint256[2] memory cmW = super.add([U_i_cmW_U_i_cmE[0], U_i_cmW_U_i_cmE[1]], mulScalarPoint); { uint256[{{num_limbs}}] memory cmW_x_limbs = LimbsDecomposition.decompose(cmW[0]); uint256[{{num_limbs}}] memory cmW_y_limbs = LimbsDecomposition.decompose(cmW[1]); for (uint8 k = 0; k < {{num_limbs}}; k++) { public_inputs[{{ z_len * 2 + 2 }} + k] = cmW_x_limbs[k]; public_inputs[{{ z_len * 2 + 2 + num_limbs }} + k] = cmW_y_limbs[k]; } } require(this.check(cmW, kzg_proof[0], challenge_W_challenge_E_kzg_evals[0], challenge_W_challenge_E_kzg_evals[2]), "KZG: verifying proof for challenge W failed"); } { // U_i.cmE + r * cmT uint256[2] memory mulScalarPoint = super.mulScalar([cmT_r[0], cmT_r[1]], cmT_r[2]); uint256[2] memory cmE = super.add([U_i_cmW_U_i_cmE[2], U_i_cmW_U_i_cmE[3]], mulScalarPoint); { uint256[{{num_limbs}}] memory cmE_x_limbs = LimbsDecomposition.decompose(cmE[0]); uint256[{{num_limbs}}] memory cmE_y_limbs = LimbsDecomposition.decompose(cmE[1]); for (uint8 k = 0; k < {{num_limbs}}; k++) { public_inputs[{{ z_len * 2 + 2 + num_limbs * 2 }} + k] = cmE_x_limbs[k]; public_inputs[{{ z_len * 2 + 2 + num_limbs * 3 }} + k] = cmE_y_limbs[k]; } } require(this.check(cmE, kzg_proof[1], challenge_W_challenge_E_kzg_evals[1], challenge_W_challenge_E_kzg_evals[3]), "KZG: verifying proof for challenge E failed"); } { // add challenges public_inputs[{{ z_len * 2 + 2 + num_limbs * 4 }}] = challenge_W_challenge_E_kzg_evals[0]; public_inputs[{{ z_len * 2 + 2 + num_limbs * 4 + 1 }}] = challenge_W_challenge_E_kzg_evals[1]; public_inputs[{{ z_len * 2 + 2 + num_limbs * 4 + 2 }}] = challenge_W_challenge_E_kzg_evals[2]; public_inputs[{{ z_len * 2 + 2 + num_limbs * 4 + 3 }}] = challenge_W_challenge_E_kzg_evals[3]; uint256[{{num_limbs}}] memory cmT_x_limbs; uint256[{{num_limbs}}] memory cmT_y_limbs; cmT_x_limbs = LimbsDecomposition.decompose(cmT_r[0]); cmT_y_limbs = LimbsDecomposition.decompose(cmT_r[1]); for (uint8 k = 0; k < {{num_limbs}}; k++) { public_inputs[{{ z_len * 2 + 2 + num_limbs * 4 }} + 4 + k] = cmT_x_limbs[k]; public_inputs[{{ z_len * 2 + 2 + num_limbs * 5 }} + 4 + k] = cmT_y_limbs[k]; } // last element of the groth16 proof's public inputs is `r` public_inputs[{{ public_inputs_len - 2 }}] = cmT_r[2]; bool success_g16 = this.verifyProof(pA, pB, pC, public_inputs); require(success_g16 == true, "Groth16: verifying proof failed"); } return(true); } }