GroupSign.md

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main.circom

pragma circom 2.1.4;

include "circomlib/poseidon.circom";
// include "https://github.com/0xPARC/circom-secp256k1/blob/master/circuits/bigint.circom";

template Secret2Public () {
    signal input sk;
    signal output pk;
    
    component poseidon = Poseidon(1); // the input of poseidon hash is the number of variables you want to hash, normally one or two
    poseidon.inputs[0] <== sk;
    pk <== poseidon.out;
    log("pk:", pk);
}

template Sign(){
    signal input m;
    signal input sk; // private
    signal output pk;

    component checker = Secret2Public();
    checker.sk <== sk;
    pk <== checker.pk;
}

template GroupSign(n){
    signal input m;
    signal input sk; // private
    signal input pk[n];
    
    component checker = Secret2Public();
    checker.sk <== sk;

    signal zeroChecker[n+1];
    zeroChecker[0] <== 1;
    for(var i = 0; i < n; i++){
        // the following line is not work because cirom cannot multiple more than 2-order to one variable
        // and the self multiple is not allowed,too
        // zeroChecker <== zeroChecker * (pk[i] - checker.pk);
        zeroChecker[i+1] <== zeroChecker[i] * (pk[i] - checker.pk);
    }
    zeroChecker[n] === 0;
}

component main  = GroupSign(5);

/* INPUT = {
    "m": "3",
    "sk": "5",
    "pk": ["19065150524771031435284970883882288895168425523179566388456001105768498065277",
        "2",
        "3",
        "4",
        "5"]
} */