circomlib/circuit/pedersen2.circom

include "montgomery.circom";
include "mux3.circom";
include "babyjub.circom";

template Window4() {
    signal input in[4];
    signal input base[2];
    signal output out[2];
    signal output out8[2];   // Returns 8*Base (To be linked)

    component mux = MultiMux3(2);

    mux.s[0] <== in[0];
    mux.s[1] <== in[1];
    mux.s[2] <== in[2];

    component dbl2 = MontgomeryDouble();
    component adr3 = MontgomeryAdd();
    component adr4 = MontgomeryAdd();
    component adr5 = MontgomeryAdd();
    component adr6 = MontgomeryAdd();
    component adr7 = MontgomeryAdd();
    component adr8 = MontgomeryAdd();

// in[0]  -> 1*BASE

    mux.c[0][0] <== base[0];
    mux.c[1][0] <== base[1];

// in[1] -> 2*BASE
    dbl2.in[0] <== base[0];
    dbl2.in[1] <== base[1];
    mux.c[0][1] <== dbl2.out[0];
    mux.c[1][1] <== dbl2.out[1];

// in[2] -> 3*BASE
    adr3.in1[0] <== base[0];
    adr3.in1[1] <== base[1];
    adr3.in2[0] <== dbl2.out[0];
    adr3.in2[1] <== dbl2.out[1];
    mux.c[0][2] <== adr3.out[0];
    mux.c[1][2] <== adr3.out[1];

// in[3] -> 4*BASE
    adr4.in1[0] <== base[0];
    adr4.in1[1] <== base[1];
    adr4.in2[0] <== adr3.out[0];
    adr4.in2[1] <== adr3.out[1];
    mux.c[0][3] <== adr4.out[0];
    mux.c[1][3] <== adr4.out[1];

// in[4] -> 5*BASE
    adr5.in1[0] <== base[0];
    adr5.in1[1] <== base[1];
    adr5.in2[0] <== adr4.out[0];
    adr5.in2[1] <== adr4.out[1];
    mux.c[0][4] <== adr5.out[0];
    mux.c[1][4] <== adr5.out[1];

// in[5] -> 6*BASE
    adr6.in1[0] <== base[0];
    adr6.in1[1] <== base[1];
    adr6.in2[0] <== adr5.out[0];
    adr6.in2[1] <== adr5.out[1];
    mux.c[0][5] <== adr6.out[0];
    mux.c[1][5] <== adr6.out[1];

// in[6] -> 7*BASE
    adr7.in1[0] <== base[0];
    adr7.in1[1] <== base[1];
    adr7.in2[0] <== adr6.out[0];
    adr7.in2[1] <== adr6.out[1];
    mux.c[0][6] <== adr7.out[0];
    mux.c[1][6] <== adr7.out[1];

// in[7] -> 8*BASE
    adr8.in1[0] <== base[0];
    adr8.in1[1] <== base[1];
    adr8.in2[0] <== adr7.out[0];
    adr8.in2[1] <== adr7.out[1];
    mux.c[0][7] <== adr8.out[0];
    mux.c[1][7] <== adr8.out[1];

    out8[0] <== adr8.out[0];
    out8[1] <== adr8.out[1];

    out[0] <== mux.out[0];
    out[1] <== - mux.out[1]*2*in[3] + mux.out[1];  // Negate y if in[3] is one
}


template Segment(nWindows) {
    signal input in[nWindows*4];
    signal input base[2];
    signal output out[2];

    var i;
    var j;

    // Convert the base to montgomery

    component e2m = Edwards2Montgomery();
    e2m.in[0] <== base[0];
    e2m.in[1] <== base[1];

    component windows[nWindows];
    component doublers1[nWindows-1];
    component doublers2[nWindows-1];
    component adders[nWindows-1];
    for (i=0; i<nWindows; i++) {
        windows[i] = Window4();
        if (i==0) {
            windows[i].base[0] <== e2m.out[0];
            windows[i].base[1] <== e2m.out[1];
        } else {
            doublers1[i-1] = MontgomeryDouble();
            doublers2[i-1] = MontgomeryDouble();
            doublers1[i-1].in[0] <== windows[i-1].out8[0];
            doublers1[i-1].in[1] <== windows[i-1].out8[1];
            doublers2[i-1].in[0] <== doublers1[i-1].out[0];
            doublers2[i-1].in[1] <== doublers1[i-1].out[1];

            windows[i].base[0] <== doublers2[i-1].out[0];
            windows[i].base[1] <== doublers2[i-1].out[1];

            adders[i-1] = MontgomeryAdd();
            if (i==1) {
                adders[i-1].in1[0] <== windows[0].out[0];
                adders[i-1].in1[1] <== windows[0].out[1];
            } else {
                adders[i-1].in1[0] <== adders[i-2].out[0];
                adders[i-1].in1[1] <== adders[i-2].out[1];
            }
            adders[i-1].in2[0] <== windows[i].out[0];
            adders[i-1].in2[1] <== windows[i].out[1];
        }
        for (j=0; j<4; j++) {
            windows[i].in[j] <== in[4*i+j];
        }
    }

    component m2e = Montgomery2Edwards();

    if (nWindows > 1) {
        m2e.in[0] <== adders[nWindows-2].out[0];
        m2e.in[1] <== adders[nWindows-2].out[1];
    } else {
        m2e.in[0] <== windows[0].out[0];
        m2e.in[1] <== windows[0].out[1];
    }

    out[0] <== m2e.out[0];
    out[1] <== m2e.out[1];
}

template Pedersen(n) {
    signal input in[n];
    signal output out[2];

    var BASE = [
        [7889815880984390413826091016397158135734961432619494935997950708325418623781,8846020814737052626835496416415322522216827521798085437978304928900248828704],
        [12932435660254426850246080929365951045207624124386035886549006330955720993567,15876660444082442781217588393435527739441124986236154572507597829115005542086],
        [2482397177297734131621151094340467680859038448217226675361423673093734165962,10039279516804305991696249700635360957313934801940294703211894781106216299926],
        [17157815998940296936592098789990444736073034804807810484873853349962905015352,6488208869655503622669430389521947006738035600928015942696596112432120303604],
        [264004460746169389447419243214191481604172623204375600962322511417379874376,2415858116338771134001541482988382151008857516531390792628421155957250972277],
        [4135925743285698117252356077971179769271452015650275231796007492648697405139,10188226868678337759614729372197905253307539893323271103976079007344248400845],
        [1774758779250924961062140611815304699163957993414252473010092444201412186500,4347026286058522695608532575722049241297833321096891696953943795644684841805],
        [7879866447646097585900946926276218605564915618236971624614091698429769712458,2093592432852088858177276030443845730480437238346603396739626046140688969347],
        [8298560996095230984182228319122592575131718101813938808256495049817179791777,1767915891871602626938298102360238720016341966012238026281701463959008338852],
        [10415885340847357003805466620366840573458521568359796855704531856219635265921,3432650026491357206165099540731361444311747596326968441647905394914712226413]
    ]

    var nSegments = ((n-1)\200)+1;

    component segments[nSegments];

    var i;
    var j;
    var nBits;
    var nWindows;
    for (i=0; i<nSegments; i++) {
        nBits = (i == (nSegments-1)) ? n - (nSegments-1)*200 : 200;
        nWindows = ((nBits - 1)\4)+1;
        segments[i] = Segment(nWindows);
        segments[i].base[0] <== BASE[i][0];
        segments[i].base[1] <== BASE[i][1];
        for (j = 0; j<nBits; j++) {
            segments[i].in[j] <== in[i*200+j];
        }
        // Fill padding bits
        for (j = nBits; j < nWindows*4; j++) {
            segments[i].in[j] <== 0;
        }
    }

    component adders[nSegments-1];

    for (i=0; i<nSegments-1; i++) {
        adders[i] = BabyAdd();
        if (i==0) {
            adders[i].x1 <== segments[0].out[0];
            adders[i].y1 <== segments[0].out[1];
            adders[i].x2 <== segments[1].out[0];
            adders[i].y2 <== segments[1].out[1];
        } else {
            adders[i].x1 <== adders[i-1].xout;
            adders[i].y1 <== adders[i-1].xout;
            adders[i].x2 <== segments[i+1].out[0];
            adders[i].y2 <== segments[i+1].out[1];
        }
    }

/*
    coponent packPoint = PackPoint();

    if (nSegments>1) {
        packPoint.in[0] <== adders[nSegments-2].xout;
        packPoint.in[1] <== adders[nSegments-2].yout;
    } else {
        packPoint.in[0] <== segments[0].out[0];
        packPoint.in[1] <== segments[0].out[1];
    }

    out[0] <== packPoint.out[0];
    out[1] <== packPoint.out[1];
*/

    if (nSegments>1) {
        out[0] <== adders[nSegments-2].xout;
        out[1] <== adders[nSegments-2].yout;
    } else {
        out[0] <== segments[0].out[0];
        out[1] <== segments[0].out[1];
    }
}