Merge branch 'kobigurk-feature/mimcsponge'

5 years ago · c84f6da970
14 changed files with 799 additions and 4 deletions
--- a/circuits/eddsamimcsponge.circom
+++ b/circuits/eddsamimcsponge.circom
@ -0,0 +1,123 @@
 /*
    Copyright 2018 0KIMS association.

    This file is part of circom (Zero Knowledge Circuit Compiler).

    circom is a free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    circom is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
    License for more details.

    You should have received a copy of the GNU General Public License
    along with circom. If not, see <https://www.gnu.org/licenses/>.
 */

 include "compconstant.circom";
 include "pointbits.circom";
 include "mimcsponge.circom";
 include "bitify.circom";
 include "escalarmulany.circom";
 include "escalarmulfix.circom";

 template EdDSAMiMCSpongeVerifier() {
    signal input enabled;
    signal input Ax;
    signal input Ay;

    signal input S;
    signal input R8x;
    signal input R8y;

    signal input M;

    var i;

 // Ensure S<Subgroup Order

    component snum2bits = Num2Bits(253);
    snum2bits.in <== S;

    component  compConstant = CompConstant(2736030358979909402780800718157159386076813972158567259200215660948447373040);

    for (i=0; i<253; i++) {
        snum2bits.out[i] ==> compConstant.in[i];
    }
    compConstant.in[253] <== 0;
    compConstant.out === 0;

 // Calculate the h = H(R,A, msg)

    component hash = MiMCSponge(5, 220, 1);
    hash.ins[0] <== R8x;
    hash.ins[1] <== R8y;
    hash.ins[2] <== Ax;
    hash.ins[3] <== Ay;
    hash.ins[4] <== M;
    hash.k <== 0;

    component h2bits = Num2Bits_strict();
    h2bits.in <== hash.outs[0];

 // Calculate second part of the right side:  right2 = h*8*A

    // Multiply by 8 by adding it 3 times.  This also ensure that the result is in
    // the subgroup.
    component dbl1 = BabyDbl();
    dbl1.x <== Ax;
    dbl1.y <== Ay;
    component dbl2 = BabyDbl();
    dbl2.x <== dbl1.xout;
    dbl2.y <== dbl1.yout;
    component dbl3 = BabyDbl();
    dbl3.x <== dbl2.xout;
    dbl3.y <== dbl2.yout;

    // We check that A is not zero.
    component isZero = IsZero();
    isZero.in <== dbl3.x;
    isZero.out === 0;

    component mulAny = EscalarMulAny(254);
    for (i=0; i<254; i++) {
        mulAny.e[i] <== h2bits.out[i];
    }
    mulAny.p[0] <== dbl3.xout;
    mulAny.p[1] <== dbl3.yout;


 // Compute the right side: right =  R8 + right2

    component addRight = BabyAdd();
    addRight.x1 <== R8x;
    addRight.y1 <== R8y;
    addRight.x2 <== mulAny.out[0];
    addRight.y2 <== mulAny.out[1];

 // Calculate left side of equation left = S*B8

    var BASE8 = [
        17777552123799933955779906779655732241715742912184938656739573121738514868268,
        2626589144620713026669568689430873010625803728049924121243784502389097019475
    ];
    component mulFix = EscalarMulFix(253, BASE8);
    for (i=0; i<253; i++) {
        mulFix.e[i] <== snum2bits.out[i];
    }

 // Do the comparation left == right if enabled;

    component eqCheckX = ForceEqualIfEnabled();
    eqCheckX.enabled <== enabled;
    eqCheckX.in[0] <== mulFix.out[0];
    eqCheckX.in[1] <== addRight.xout;

    component eqCheckY = ForceEqualIfEnabled();
    eqCheckY.enabled <== enabled;
    eqCheckY.in[0] <== mulFix.out[1];
    eqCheckY.in[1] <== addRight.yout;
 }
--- a/circuits/mimcsponge.circom
+++ b/circuits/mimcsponge.circom
@ -0,0 +1,283 @@
 // implements MiMC-2n/n as hash using a sponge construction.
 // log_5(21888242871839275222246405745257275088548364400416034343698204186575808495617) ~= 110
 // => nRounds should be 220
 template MiMCSponge(nInputs, nRounds, nOutputs) {
  signal input ins[nInputs];
  signal input k;
  signal output outs[nOutputs];

  // S = R||C
  component S[nInputs + nOutputs - 1];

  for (var i = 0; i < nInputs; i++) {
    S[i] = MiMCFeistel(nRounds);
    S[i].k <== k;
    if (i == 0) {
      S[i].xL_in <== ins[0];
      S[i].xR_in <== 0;
    } else {
      S[i].xL_in <== S[i-1].xL_out + ins[i];
      S[i].xR_in <== S[i-1].xR_out;
    }
  }

  outs[0] = S[nInputs - 1].xL_out;

  for (var i = 0; i < nOutputs - 1; i++) {
    S[nInputs + i] = MiMCFeistel(nRounds);
    S[nInputs + i].k <== k;
    S[nInputs + i].xL_in <== S[nInputs + i - 1].xL_out;
    S[nInputs + i].xR_in <== S[nInputs + i - 1].xR_out;
    outs[i + 1] <== S[nInputs + i].xL_out;
  }
 }

 template MiMCFeistel(nrounds) {
    signal input xL_in;
    signal input xR_in;
    signal input k;
    signal output xL_out;
    signal output xR_out;

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      9783723818270121678386992630754842961728702994964214799008457449989291229500,
      15550788416669474113213749561488122552422887538676036667630838378023479382689,
      15016165746156232864069722572047169071786333815661109750860165034341572904221,
      6506225705710197163670556961299945987488979904603689017479840649664564978574,
      10796631184889302076168355684722130903785890709107732067446714470783437829037,
      19871836214837460419845806980869387567383718044439891735114283113359312279540,
      20871081766843466343749609089986071784031203517506781251203251608363835140622,
      5100105771517691442278432864090229416166996183792075307747582375962855820797,
      8777887112076272395250620301071581171386440850451972412060638225741125310886,
      5300440870136391278944213332144327695659161151625757537632832724102670898756,
      1205448543652932944633962232545707633928124666868453915721030884663332604536,
      5542499997310181530432302492142574333860449305424174466698068685590909336771,
      11028094245762332275225364962905938096659249161369092798505554939952525894293,
      19187314764836593118404597958543112407224947638377479622725713735224279297009,
      17047263688548829001253658727764731047114098556534482052135734487985276987385,
      19914849528178967155534624144358541535306360577227460456855821557421213606310,
      2929658084700714257515872921366736697080475676508114973627124569375444665664,
      15092262360719700162343163278648422751610766427236295023221516498310468956361,
      21578580340755653236050830649990190843552802306886938815497471545814130084980,
      1258781501221760320019859066036073675029057285507345332959539295621677296991,
      3819598418157732134449049289585680301176983019643974929528867686268702720163,
      8653175945487997845203439345797943132543211416447757110963967501177317426221,
      6614652990340435611114076169697104582524566019034036680161902142028967568142,
      19212515502973904821995111796203064175854996071497099383090983975618035391558,
      18664315914479294273286016871365663486061896605232511201418576829062292269769,
      11498264615058604317482574216318586415670903094838791165247179252175768794889,
      10814026414212439999107945133852431304483604215416531759535467355316227331774,
      17566185590731088197064706533119299946752127014428399631467913813769853431107,
      14016139747289624978792446847000951708158212463304817001882956166752906714332,
      8242601581342441750402731523736202888792436665415852106196418942315563860366,
      9244680976345080074252591214216060854998619670381671198295645618515047080988,
      12216779172735125538689875667307129262237123728082657485828359100719208190116,
      10702811721859145441471328511968332847175733707711670171718794132331147396634,
      6479667912792222539919362076122453947926362746906450079329453150607427372979,
      15117544653571553820496948522381772148324367479772362833334593000535648316185,
      6842203153996907264167856337497139692895299874139131328642472698663046726780,
      12732823292801537626009139514048596316076834307941224506504666470961250728055,
      6936272626871035740815028148058841877090860312517423346335878088297448888663,
      17297554111853491139852678417579991271009602631577069694853813331124433680030,
      16641596134749940573104316021365063031319260205559553673368334842484345864859,
      7400481189785154329569470986896455371037813715804007747228648863919991399081,
      2273205422216987330510475127669563545720586464429614439716564154166712854048,
      15162538063742142685306302282127534305212832649282186184583465569986719234456,
      5628039096440332922248578319648483863204530861778160259559031331287721255522,
      16085392195894691829567913404182676871326863890140775376809129785155092531260,
      14227467863135365427954093998621993651369686288941275436795622973781503444257,
      18224457394066545825553407391290108485121649197258948320896164404518684305122,
      274945154732293792784580363548970818611304339008964723447672490026510689427,
      11050822248291117548220126630860474473945266276626263036056336623671308219529,
      2119542016932434047340813757208803962484943912710204325088879681995922344971,
      0
    ];

    var t;
    signal t2[nrounds];
    signal t4[nrounds];
    signal xL[nrounds-1];
    signal xR[nrounds-1];

    for (var i=0; i<nrounds; i++) {
        t = (i==0) ? k+xL_in : k + xL[i-1] + c[i];
        t2[i] <== t*t;
        t4[i] <== t2[i]*t2[i];
        if (i<nrounds-1) {
          xL[i] <== ((i==0) ? xR_in : xR[i-1]) + t4[i]*t;
          xR[i] = (i==0) ? xL_in : xL[i-1];
        } else {
          xR_out <== xR[i-1] + t4[i]*t;
          xL_out <== xL[i-1];
        }
    }
 }
--- a/index.js
+++ b/index.js
@ -1,5 +1,6 @@
 exports.smt = require("./src/smt");
 exports.eddsa = require("./src/eddsa");
 exports.mimc7 = require("./src/mimc7");
 exports.mimcsponge = require("./src/mimcsponge");
 exports.babyJub = require("./src/babyjub");
 exports.pedersenHash = require("./src/pedersenHash");
--- a/package-lock.json
+++ b/package-lock.json
@ -3909,7 +3909,7 @@
    },
    "os-tmpdir": {
      "version": "1.0.2",
      "resolved": "http://registry.npmjs.org/os-tmpdir/-/os-tmpdir-1.0.2.tgz",
      "resolved": "https://registry.npmjs.org/os-tmpdir/-/os-tmpdir-1.0.2.tgz",
      "integrity": "sha1-u+Z0BseaqFxc/sdm/lc0VV36EnQ="
    },
    "p-defer": {
@ -4785,7 +4785,7 @@
    },
    "sprintf-js": {
      "version": "1.0.3",
      "resolved": "http://registry.npmjs.org/sprintf-js/-/sprintf-js-1.0.3.tgz",
      "resolved": "https://registry.npmjs.org/sprintf-js/-/sprintf-js-1.0.3.tgz",
      "integrity": "sha1-BOaSb2YolTVPPdAVIDYzuFcpfiw="
    },
    "stack-trace": {
--- a/src/eddsa.js
+++ b/src/eddsa.js
@ -4,14 +4,17 @@ const babyJub = require("./babyjub");
 const pedersenHash = require("./pedersenHash").hash;
 const mimc7 = require("./mimc7");
 const poseidon = require("./poseidon.js");
 const mimcsponge = require("./mimcsponge");

 exports.prv2pub= prv2pub;
 exports.sign = sign;
 exports.signMiMC = signMiMC;
 exports.signPoseidon = signPoseidon;
 exports.signMiMCSponge = signMiMCSponge;
 exports.verify = verify;
 exports.verifyMiMC = verifyMiMC;
 exports.verifyPoseidon = verifyPoseidon;
 exports.verifyMiMCSponge = verifyMiMCSponge;
 exports.packSignature = packSignature;
 exports.unpackSignature = unpackSignature;
 exports.pruneBuffer = pruneBuffer;
@ -72,6 +75,24 @@ function signMiMC(prv, msg) {
    };
 }

 function signMiMCSponge(prv, msg) {
    const h1 = createBlakeHash("blake512").update(prv).digest();
    const sBuff = pruneBuffer(h1.slice(0,32));
    const s = bigInt.leBuff2int(sBuff);
    const A = babyJub.mulPointEscalar(babyJub.Base8, s.shr(3));

    const msgBuff = bigInt.leInt2Buff(msg, 32);
    const rBuff = createBlakeHash("blake512").update(Buffer.concat([h1.slice(32,64), msgBuff])).digest();
    let r = bigInt.leBuff2int(rBuff);
    r = r.mod(babyJub.subOrder);
    const R8 = babyJub.mulPointEscalar(babyJub.Base8, r);
    const hm = mimcsponge.multiHash([R8[0], R8[1], A[0], A[1], msg]);
    const S = r.add(hm.mul(s)).mod(babyJub.subOrder);
    return {
        R8: R8,
        S: S
    };
 }

 function signPoseidon(prv, msg) {
    const h1 = createBlakeHash("blake512").update(prv).digest();
@ -84,9 +105,7 @@ function signPoseidon(prv, msg) {
    let r = bigInt.leBuff2int(rBuff);
    r = r.mod(babyJub.subOrder);
    const R8 = babyJub.mulPointEscalar(babyJub.Base8, r);

    const hash = poseidon.createHash(6, 8, 57);

    const hm = hash([R8[0], R8[1], A[0], A[1], msg]);
    const S = r.add(hm.mul(s)).mod(babyJub.subOrder);
    return {
@ -166,6 +185,28 @@ function verifyPoseidon(msg, sig, A) {
    return true;
 }

 function verifyMiMCSponge(msg, sig, A) {
    // Check parameters
    if (typeof sig != "object") return false;
    if (!Array.isArray(sig.R8)) return false;
    if (sig.R8.length!= 2) return false;
    if (!babyJub.inCurve(sig.R8)) return false;
    if (!Array.isArray(A)) return false;
    if (A.length!= 2) return false;
    if (!babyJub.inCurve(A)) return false;
    if (sig.S>= babyJub.subOrder) return false;

    const hm = mimcsponge.multiHash([sig.R8[0], sig.R8[1], A[0], A[1], msg]);

    const Pleft = babyJub.mulPointEscalar(babyJub.Base8, sig.S);
    let Pright = babyJub.mulPointEscalar(A, hm.mul(bigInt("8")));
    Pright = babyJub.addPoint(sig.R8, Pright);

    if (!Pleft[0].equals(Pright[0])) return false;
    if (!Pleft[1].equals(Pright[1])) return false;
    return true;
 }

 function packSignature(sig) {
    const R8p = babyJub.packPoint(sig.R8);
    const Sp = bigInt.leInt2Buff(sig.S, 32);
--- a/src/mimc_printconstants..js
+++ b/src/mimc_printconstants..js
--- a/src/mimcsponge.js
+++ b/src/mimcsponge.js
@ -0,0 +1,86 @@
 const bn128 = require("snarkjs").bn128;
 const bigInt = require("snarkjs").bigInt;
 const Web3Utils = require("web3-utils");
 const F = bn128.Fr;

 const SEED = "mimcsponge";
 const NROUNDS = 220;

 exports.getIV = (seed) => {
    if (typeof seed === "undefined") seed = SEED;
    const c = Web3Utils.keccak256(seed+"_iv");
    const cn = bigInt(Web3Utils.toBN(c).toString());
    const iv = cn.mod(F.q);
    return iv;
 };

 exports.getConstants = (seed, nRounds) => {
    if (typeof seed === "undefined") seed = SEED;
    if (typeof nRounds === "undefined") nRounds = NROUNDS;
    const cts = new Array(nRounds);
    let c = Web3Utils.keccak256(SEED);
    for (let i=1; i<nRounds; i++) {
        c = Web3Utils.keccak256(c);

        const n1 = Web3Utils.toBN(c).mod(Web3Utils.toBN(F.q.toString()));
        const c2 = Web3Utils.padLeft(Web3Utils.toHex(n1), 64);
        cts[i] = bigInt(Web3Utils.toBN(c2).toString());
    }
    cts[0] = bigInt(0);
    cts[cts.length - 1] = bigInt(0);
    return cts;
 };

 const cts = exports.getConstants(SEED, NROUNDS);

 exports.hash = (_xL_in, _xR_in, _k) =>{
    let xL = bigInt(_xL_in);
    let xR = bigInt(_xR_in);
    const k = bigInt(_k);
    for (let i=0; i<NROUNDS; i++) {
        const c = cts[i];
        const t = (i==0) ? F.add(xL, k) : F.add(F.add(xL, k), c);
        const xR_tmp = bigInt(xR);
        if (i < (NROUNDS - 1)) {
          xR = xL;
          xL = F.add(xR_tmp, F.exp(t, 5));
        } else {
          xR = F.add(xR_tmp, F.exp(t, 5));
        }
    }
    return {
      xL: F.affine(xL),
      xR: F.affine(xR),
    };
 };

 exports.multiHash = (arr, key, numOutputs) => {
    if (typeof(numOutputs) === "undefined") {
      numOutputs = 1;
    }
    if (typeof(key) === "undefined") {
        key = F.zero;
    }

    let R = F.zero;
    let C = F.zero;

    for (let i=0; i<arr.length; i++) {
      R = F.add(R, bigInt(arr[i]));
      const S = exports.hash(R, C, key);
      R = S.xL;
      C = S.xR;
    }
    let outputs = [R];
    for (let i=1; i < numOutputs; i++) {
      const S = exports.hash(R, C, key);
      R = S.xL;
      C = S.xR;
      outputs.push(R);
    }
    if (numOutputs == 1) {
      return F.affine(outputs[0]);
    } else {
      return outputs.map(x => F.affine(x));
    }
 };
--- a/src/mimcsponge_gencontract.js
+++ b/src/mimcsponge_gencontract.js
@ -0,0 +1,128 @@
 // Copyright (c) 2018 Jordi Baylina
 // License: LGPL-3.0+
 //

 const Web3Utils = require("web3-utils");

 const Contract = require("./evmasm");

 function createCode(seed, n) {

    let ci = Web3Utils.keccak256(seed);

    const C = new Contract();

    C.push(0x64);
    C.push("0x00");
    C.push("0x00");
    C.calldatacopy();
    C.push("0x0100000000000000000000000000000000000000000000000000000000");
    C.push("0x00");
    C.mload();
    C.div();
    C.push("0x3f1a1187"); // MiMCSponge(uint256,uint256,uint256)
    C.eq();
    C.jmpi("start");
    C.invalid();

    C.label("start");
    C.push("0x30644e72e131a029b85045b68181585d2833e84879b9709143e1f593f0000001");  // q
    C.push("0x44");
    C.mload();          // k q
    C.push("0x04");
    C.mload();          // xL k q
    C.dup(2);           // q xL k q
    C.push("0x24");
    C.mload();          // xR q xL k q
    C.dup(1);           // q xR q xL k q
    C.dup(0);           // q q xR q xL k q
    C.dup(4);           // xL q q xR q xL k q
    C.dup(6);           // k xL q q xR q xL k q
    C.addmod();         // t=k+xL q xR q xL k q
    C.dup(1);           // q t q xR q xL k q
    C.dup(0);           // q q t q xR q xL k q
    C.dup(2);           // t q q t q xR q xL k q
    C.dup(0);           // t t q q t q xR q xL k q
    C.mulmod();         // b=t^2 q t q xR q xL k q
    C.dup(0);           // b b q t q xR q xL k q
    C.mulmod();         // c=t^4 t q xR q xL k q
    C.mulmod();         // d=t^5 xR q xL k q
    C.addmod();         // e=t^5+xR xL k q (for next round: xL xR k q)

    for (let i=0; i<n-1; i++) {
        if (i < n-2) {
          ci = Web3Utils.keccak256(ci);
        } else {
          ci = "0x00";
        }
        C.swap(1);      // xR xL k q
        C.dup(3);       // q xR xL k q
        C.dup(3);       // k q xR xL k q
        C.dup(1);       // q k q xR xL k q
        C.dup(4);       // xL q k q xR xL k q
        C.push(ci);     // ci xL q k q xR xL k q
        C.addmod();     // a=ci+xL k q xR xL k q
        C.addmod();     // t=a+k xR xL k q
        C.dup(4);       // q t xR xL k q
        C.swap(1);      // t q xR xL k q
        C.dup(1);       // q t q xR xL k q
        C.dup(0);       // q q t q xR xL k q
        C.dup(2);       // t q q t q xR xL k q
        C.dup(0);       // t t q q t q xR xL k q
        C.mulmod();     // b=t^2 q t q xR xL k q
        C.dup(0);       // b b q t q xR xL k q
        C.mulmod();     // c=t^4 t q xR xL k q
        C.mulmod();     // d=t^5 xR xL k q
        C.dup(4);       // q d xR xL k q
        C.swap(2);      // xR d q xL k q
        C.addmod();     // e=t^5+xR xL k q (for next round: xL xR k q)
    }

    C.push("0x20");
    C.mstore();     // Save it to pos 0;
    C.push("0x00");
    C.mstore();     // Save it to pos 1;
    C.push("0x40");
    C.push("0x00");
    C.return();

    return C.createTxData();
 }

 module.exports.abi = [
    {
        "constant": true,
        "inputs": [
            {
                "name": "xL_in",
                "type": "uint256"
            },
            {
                "name": "xR_in",
                "type": "uint256"
            },
            {
                "name": "k",
                "type": "uint256"
            }
        ],
        "name": "MiMCSponge",
        "outputs": [
            {
                "name": "xL",
                "type": "uint256"
            },
            {
                "name": "xR",
                "type": "uint256"
            }
        ],
        "payable": false,
        "stateMutability": "pure",
        "type": "function"
    }
 ];

 module.exports.createCode = createCode;


--- a/src/mimcsponge_printconstants.js
+++ b/src/mimcsponge_printconstants.js
@ -0,0 +1,13 @@
 const mimcsponge = require("./mimcsponge.js");

 const nRounds = 220;
 let S = "[\n";
 const cts = mimcsponge.getConstants();
 for (let i=0; i<nRounds; i++) {
    S = S + cts[i].toString();
    if (i<nRounds-1) S = S + ",";
    S=S+"\n";
 }
 S = S + "]\n";

 console.log(S);
--- a/src/mimcsponge_printcontract.js
+++ b/src/mimcsponge_printcontract.js
@ -0,0 +1,13 @@
 const mimcGenContract = require("./mimcsponge_gencontract");

 const SEED = "mimcsponge";

 let nRounds;
 if (typeof process.argv[2] != "undefined") {
    nRounds = parseInt(process.argv[2]);
 } else {
    nRounds = 220;
 }

 console.log(mimcGenContract.createCode(SEED, nRounds));

--- a/test/circuits/mimc_sponge_hash_test.circom
+++ b/test/circuits/mimc_sponge_hash_test.circom
@ -0,0 +1,3 @@
 include "../../circuits/mimcsponge.circom"

 component main = MiMCSponge(2, 220, 3);
--- a/test/circuits/mimc_sponge_test.circom
+++ b/test/circuits/mimc_sponge_test.circom
@ -0,0 +1,3 @@
 include "../../circuits/mimcsponge.circom"

 component main = MiMCFeistel(220);
--- a/test/mimcspongecircuit.js
+++ b/test/mimcspongecircuit.js
@ -0,0 +1,58 @@
 const chai = require("chai");
 const path = require("path");
 const snarkjs = require("snarkjs");
 const compiler = require("circom");

 const mimcjs = require("../src/mimcsponge.js");

 const assert = chai.assert;

 describe("MiMC Sponge Circuit test", function () {
    let circuit;

    this.timeout(100000);

    it("Should check permutation", async () => {
        const cirDef = await compiler(path.join(__dirname, "circuits", "mimc_sponge_test.circom"));

        circuit = new snarkjs.Circuit(cirDef);

        console.log("MiMC Feistel constraints: " + circuit.nConstraints);

        const w = circuit.calculateWitness({xL_in: 1, xR_in: 2, k: 3});

        const xLout = w[circuit.getSignalIdx("main.xL_out")];
        const xRout = w[circuit.getSignalIdx("main.xR_out")];

        const out2 = mimcjs.hash(1,2,3);

        assert.equal(xLout.toString(), out2.xL.toString());
        assert.equal(xRout.toString(), out2.xR.toString());

        assert(circuit.checkWitness(w));

    });

    it("Should check hash", async () => {
        const cirDef = await compiler(path.join(__dirname, "circuits", "mimc_sponge_hash_test.circom"));

        circuit = new snarkjs.Circuit(cirDef);

        console.log("MiMC Sponge constraints: " + circuit.nConstraints);

        const w = circuit.calculateWitness({ins: [1, 2], k: 0});

        const o1 = w[circuit.getSignalIdx("main.outs[0]")];
        const o2 = w[circuit.getSignalIdx("main.outs[1]")];
        const o3 = w[circuit.getSignalIdx("main.outs[2]")];

        const out2 = mimcjs.multiHash([1,2], 0, 3);

        assert.equal(o1.toString(), out2[0].toString());
        assert.equal(o2.toString(), out2[1].toString());
        assert.equal(o3.toString(), out2[2].toString());

        assert(circuit.checkWitness(w));

    });
 });
--- a/test/mimcspongecontract.js
+++ b/test/mimcspongecontract.js
@ -0,0 +1,43 @@
 const ganache = require("ganache-cli");
 const Web3 = require("web3");
 const chai = require("chai");
 const mimcGenContract = require("../src/mimcsponge_gencontract.js");
 const mimcjs = require("../src/mimcsponge.js");


 const assert = chai.assert;
 const log = (msg) => { if (process.env.MOCHA_VERBOSE) console.log(msg); };

 const SEED = "mimcsponge";

 describe("MiMC Sponge Smart contract test", () => {
    let testrpc;
    let web3;
    let mimc;
    let accounts;

    before(async () => {
        web3 = new Web3(ganache.provider(), null, { transactionConfirmationBlocks: 1 });
        accounts = await web3.eth.getAccounts();
    });

    it("Should deploy the contract", async () => {
        const C = new web3.eth.Contract(mimcGenContract.abi);

        mimc = await C.deploy({
            data: mimcGenContract.createCode(SEED, 220)
        }).send({
            gas: 3500000,
            from: accounts[0]
        });
    });

    it("Shold calculate the mimc correctly", async () => {
        const res = await mimc.methods.MiMCSponge(1,2,3).call();
        const res2 = await mimcjs.hash(1,2,3);

        assert.equal(res.xL.toString(), res2.xL.toString());
        assert.equal(res.xR.toString(), res2.xR.toString());
    });
 });