circomlib/circuits/smt/smtverifier.circom
2019-12-14 20:32:45 +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/>.
*/
/*
SMTVerifier is a component to verify inclusion/exclusion of an element in the tree
fnc: 0 -> VERIFY INCLUSION
1 -> VERIFY NOT INCLUSION
*/
include "../gates.circom";
include "../bitify.circom";
include "../comparators.circom";
include "../switcher.circom";
include "smtlevins.circom";
include "smtverifierlevel.circom";
include "smtverifiersm.circom";
include "smthash_poseidon.circom";
template SMTVerifier(nLevels) {
signal input enabled;
signal input root;
signal input siblings[nLevels];
signal input oldKey;
signal input oldValue;
signal input isOld0;
signal input key;
signal input value;
signal input fnc;
var i;
component hash1Old = SMTHash1();
hash1Old.key <== oldKey;
hash1Old.value <== oldValue;
component hash1New = SMTHash1();
hash1New.key <== key;
hash1New.value <== value;
component n2bOld = Num2Bits_strict();
component n2bNew = Num2Bits_strict();
n2bOld.in <== oldKey;
n2bNew.in <== key;
component smtLevIns = SMTLevIns(nLevels);
for (i=0; i<nLevels; i++) smtLevIns.siblings[i] <== siblings[i];
smtLevIns.enabled <== enabled;
component sm[nLevels];
for (i=0; i<nLevels; i++) {
sm[i] = SMTVerifierSM();
if (i==0) {
sm[i].prev_top <== enabled;
sm[i].prev_i0 <== 0;
sm[i].prev_inew <== 0;
sm[i].prev_iold <== 0;
sm[i].prev_na <== 1-enabled;
} else {
sm[i].prev_top <== sm[i-1].st_top;
sm[i].prev_i0 <== sm[i-1].st_i0;
sm[i].prev_inew <== sm[i-1].st_inew;
sm[i].prev_iold <== sm[i-1].st_iold;
sm[i].prev_na <== sm[i-1].st_na;
}
sm[i].is0 <== isOld0;
sm[i].fnc <== fnc;
sm[i].levIns <== smtLevIns.levIns[i];
}
sm[nLevels-1].st_na + sm[nLevels-1].st_iold + sm[nLevels-1].st_inew + sm[nLevels-1].st_i0 === 1;
component levels[nLevels];
for (i=nLevels-1; i != -1; i--) {
levels[i] = SMTVerifierLevel();
levels[i].st_top <== sm[i].st_top;
levels[i].st_i0 <== sm[i].st_i0;
levels[i].st_inew <== sm[i].st_inew;
levels[i].st_iold <== sm[i].st_iold;
levels[i].st_na <== sm[i].st_na;
levels[i].sibling <== siblings[i];
levels[i].old1leaf <== hash1Old.out;
levels[i].new1leaf <== hash1New.out;
levels[i].lrbit <== n2bNew.out[i];
if (i==nLevels-1) {
levels[i].child <== 0;
} else {
levels[i].child <== levels[i+1].root;
}
}
// Check that if checking for non inclussuin and isOld0==0 then key!=old
component areKeyEquals = IsEqual();
areKeyEquals.in[0] <== oldKey;
areKeyEquals.in[1] <== key;
component keysOk = MultiAND(4);
keysOk.in[0] <== fnc;
keysOk.in[1] <== 1-isOld0;
keysOk.in[2] <== areKeyEquals.out;
keysOk.in[3] <== enabled;
keysOk.out === 0;
// Check the root
component checkRoot = ForceEqualIfEnabled();
checkRoot.enabled <== enabled;
checkRoot.in[0] <== levels[0].root;
checkRoot.in[1] <== root;
// levels[0].root === root;
}