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fix: makes mimcsponge act like the paper description 

* last constant is 0
* no swap at the last round
This commit is contained in:
Kobi Gurkan 2019-07-07 15:01:14 +03:00
parent 9e078dc299
commit 324b8bf8cc
2 changed files with 11 additions and 6 deletions
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6
circuits/mimcsponge.circom
View File

@ -259,7 +259,7 @@ template MiMCFeistel(nrounds) {
274945154732293792784580363548970818611304339008964723447672490026510689427,
11050822248291117548220126630860474473945266276626263036056336623671308219529,
2119542016932434047340813757208803962484943912710204325088879681995922344971,
12785816057369026966653780180257549951796705239580629452502836335892168319323
0
];
var t;
@ -276,8 +276,8 @@ template MiMCFeistel(nrounds) {
xL[i] <== ((i==0) ? xR_in : xR[i-1]) + t4[i]*t;
xR[i] = (i==0) ? xL_in : xL[i-1];
} else {
xL_out <== xR[i-1] + t4[i]*t;
xR_out <== xL[i-1];
xR_out <== xR[i-1] + t4[i]*t;
xL_out <== xL[i-1];
}
}
}

7
src/mimcsponge.js
View File

@ -27,10 +27,11 @@ exports.getConstants = (seed, nRounds) => {
cts[i] = bigInt(Web3Utils.toBN(c2).toString());
}
cts[0] = bigInt(0);
cts[cts.length - 1] = bigInt(0);
return cts;
};
const cts = exports.getConstants(SEED, 220);
const cts = exports.getConstants(SEED, NROUNDS);
exports.hash = (_xL_in, _xR_in, _k) =>{
let xL = bigInt(_xL_in);
@ -40,8 +41,12 @@ exports.hash = (_xL_in, _xR_in, _k) =>{
const c = cts[i];
const t = (i==0) ? F.add(xL, k) : F.add(F.add(xL, k), c);
const xR_tmp = bigInt(xR);
if (i < (NROUNDS - 1)) {
xR = xL;
xL = F.add(xR_tmp, F.exp(t, 5));
} else {
xR = F.add(xR_tmp, F.exp(t, 5));
}
}
return {
xL: F.affine(xL),