Files
darkfi/proof/voting.zk
parazyd 6a024ab801 zkas: Add a field definition on top of the circuit file.
Currently unused, but will probably be expanded to define proofs over
different fields.
2023-08-14 17:09:18 +02:00

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k = 13;
field = "pallas";
constant "Vote" {
EcFixedPointShort VALUE_COMMIT_VALUE,
EcFixedPoint VALUE_COMMIT_RANDOM,
EcFixedPointBase NULLIFIER_K,
}
witness "Vote" {
Base process_id_0,
Base process_id_1,
Base secret_key,
Base vote,
Scalar vote_blind,
Uint32 leaf_pos,
MerklePath path,
}
circuit "Vote" {
# Nullifier hash
process_id = poseidon_hash(process_id_0, process_id_1);
nullifier = poseidon_hash(secret_key, process_id);
constrain_instance(nullifier);
# Public key derivation and hashing
public_key = ec_mul_base(secret_key, NULLIFIER_K);
public_x = ec_get_x(public_key);
public_y = ec_get_y(public_key);
pk_hash = poseidon_hash(public_x, public_y);
# Merkle root
root = merkle_root(leaf_pos, path, pk_hash);
constrain_instance(root);
# Pedersen commitment for vote
vcv = ec_mul_short(vote, VALUE_COMMIT_VALUE);
vcr = ec_mul(vote_blind, VALUE_COMMIT_RANDOM);
vote_commit = ec_add(vcv, vcr);
# Since vote_commit is a curve point, we fetch its coordinates
# and constrain_them:
vote_commit_x = ec_get_x(vote_commit);
vote_commit_y = ec_get_y(vote_commit);
constrain_instance(vote_commit_x);
constrain_instance(vote_commit_y);
}