circomlib/circuits/eddsamimc.circom
2019-04-28 12:03:15 +01:00

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/*
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 "mimc.circom";
include "bitify.circom";
include "escalarmulany.circom";
include "escalarmulfix.circom";
template EdDSAMiMCVerifier() {
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 = MultiMiMC7(5, 91);
hash.in[0] <== R8x;
hash.in[1] <== R8y;
hash.in[2] <== Ax;
hash.in[3] <== Ay;
hash.in[4] <== M;
hash.k <== 0;
component h2bits = Num2Bits_strict();
h2bits.in <== hash.out;
// 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;
}