1/*
  2    Copyright 2018 0KIMS association.
  3
  4    This file is part of circom (Zero Knowledge Circuit Compiler).
  5
  6    circom is a free software: you can redistribute it and/or modify it
  7    under the terms of the GNU General Public License as published by
  8    the Free Software Foundation, either version 3 of the License, or
  9    (at your option) any later version.
 10
 11    circom is distributed in the hope that it will be useful, but WITHOUT
 12    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 13    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
 14    License for more details.
 15
 16    You should have received a copy of the GNU General Public License
 17    along with circom. If not, see <https://www.gnu.org/licenses/>.
 18*/
 19
 20/*
 21
 22SMTVerifier is a component to verify inclusion/exclusion of an element in the tree
 23
 24
 25fnc:  0 -> VERIFY INCLUSION
 26      1 -> VERIFY NOT INCLUSION
 27
 28 */
 29 pragma circom 2.0.0;
 30
 31
 32include "../gates.circom";
 33include "../bitify.circom";
 34include "../comparators.circom";
 35include "../switcher.circom";
 36include "smtlevins.circom";
 37include "smtverifierlevel.circom";
 38include "smtverifiersm.circom";
 39include "smthash_poseidon.circom";
 40
 41template SMTVerifier(nLevels) {
 42    signal input enabled;
 43    signal input root;
 44    signal input siblings[nLevels];
 45    signal input oldKey;
 46    signal input oldValue;
 47    signal input isOld0;
 48    signal input key;
 49    signal input value;
 50    signal input fnc;
 51
 52    var i;
 53
 54    component hash1Old = SMTHash1();
 55    hash1Old.key <== oldKey;
 56    hash1Old.value <== oldValue;
 57
 58    component hash1New = SMTHash1();
 59    hash1New.key <== key;
 60    hash1New.value <== value;
 61
 62    component n2bOld = Num2Bits_strict();
 63    component n2bNew = Num2Bits_strict();
 64
 65    n2bOld.in <== oldKey;
 66    n2bNew.in <== key;
 67
 68    component smtLevIns = SMTLevIns(nLevels);
 69    for (i=0; i<nLevels; i++) smtLevIns.siblings[i] <== siblings[i];
 70    smtLevIns.enabled <== enabled;
 71
 72    component sm[nLevels];
 73    for (i=0; i<nLevels; i++) {
 74        sm[i] = SMTVerifierSM();
 75        if (i==0) {
 76            sm[i].prev_top <== enabled;
 77            sm[i].prev_i0 <== 0;
 78            sm[i].prev_inew <== 0;
 79            sm[i].prev_iold <== 0;
 80            sm[i].prev_na <== 1-enabled;
 81        } else {
 82            sm[i].prev_top <== sm[i-1].st_top;
 83            sm[i].prev_i0 <== sm[i-1].st_i0;
 84            sm[i].prev_inew <== sm[i-1].st_inew;
 85            sm[i].prev_iold <== sm[i-1].st_iold;
 86            sm[i].prev_na <== sm[i-1].st_na;
 87        }
 88        sm[i].is0 <== isOld0;
 89        sm[i].fnc <== fnc;
 90        sm[i].levIns <== smtLevIns.levIns[i];
 91    }
 92    sm[nLevels-1].st_na + sm[nLevels-1].st_iold + sm[nLevels-1].st_inew + sm[nLevels-1].st_i0 === 1;
 93
 94    component levels[nLevels];
 95    for (i=nLevels-1; i != -1; i--) {
 96        levels[i] = SMTVerifierLevel();
 97
 98        levels[i].st_top <== sm[i].st_top;
 99        levels[i].st_i0 <== sm[i].st_i0;
100        levels[i].st_inew <== sm[i].st_inew;
101        levels[i].st_iold <== sm[i].st_iold;
102        levels[i].st_na <== sm[i].st_na;
103
104        levels[i].sibling <== siblings[i];
105        levels[i].old1leaf <== hash1Old.out;
106        levels[i].new1leaf <== hash1New.out;
107
108        levels[i].lrbit <== n2bNew.out[i];
109        if (i==nLevels-1) {
110            levels[i].child <== 0;
111        } else {
112            levels[i].child <== levels[i+1].root;
113        }
114    }
115
116
117    // Check that if checking for non inclussuin and isOld0==0 then key!=old
118    component areKeyEquals = IsEqual();
119    areKeyEquals.in[0] <== oldKey;
120    areKeyEquals.in[1] <== key;
121
122    component keysOk = MultiAND(4);
123    keysOk.in[0] <== fnc;
124    keysOk.in[1] <== 1-isOld0;
125    keysOk.in[2] <== areKeyEquals.out;
126    keysOk.in[3] <== enabled;
127
128    keysOk.out === 0;
129
130    // Check the root
131    component checkRoot = ForceEqualIfEnabled();
132    checkRoot.enabled <== enabled;
133    checkRoot.in[0] <== levels[0].root;
134    checkRoot.in[1] <== root;
135
136    // levels[0].root === root;
137
138}