circomlib/circuits/multiplexer.circom
2018-12-06 17:32:49 +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/>.
*/
// --> Assignation without constraint
// <-- Assignation without constraint
// === Constraint
// <== Assignation with constraint
// ==> Assignation with constraint
// All variables are members of the field F[p]
// https://github.com/zcash-hackworks/sapling-crypto
// https://github.com/ebfull/bellman
/*
function log2(a) {
if (a==0) {
return 0;
}
let n = 1;
let r = 1;
while (n<a) {
r++;
n *= 2;
}
return r;
}
*/
template EscalarProduct(w) {
signal input in1[w];
signal input in2[w];
signal output out;
signal aux[w];
var lc = 0;
for (var i=0; i<w; i++) {
aux[i] <== in1[i]*in2[i];
lc = lc + aux[i];
}
out <== lc;
}
template Decoder(w) {
signal input inp;
signal output out[w];
signal output success;
var lc=0;
for (var i=0; i<w; i++) {
out[i] <-- (inp == i) ? 1 : 0;
out[i] * (inp-i) === 0;
lc = lc + out[i];
}
lc ==> success;
success * (success -1) === 0;
}
template Multiplexor(wIn, nIn) {
signal input inp[nIn][wIn];
signal input sel;
signal output out[wIn];
component Decoder(nIn) dec;
component EscalarProduct(nIn) ep[wIn];
sel ==> dec.inp;
for (var j=0; j<wIn; j++) {
for (var k=0; k<nIn; k++) {
inp[k][j] ==> ep[j].in1[k];
dec.out[k] ==> ep[j].in2[k];
}
ep[j].out ==> out[j];
}
dec.success === 1;
}
component Multiplexor(8,3) main;