circomlib · arnaucube's git mirror

fix: makes mimcsponge act like the paper description

* last constant is 0
* no swap at the last round

Kobi Gurkan kobigurk@gmail.com

Sun, 07 Jul 2019 15:01:14 +0300

commit

324b8bf8cc4a80357354752deb6c2ae5be22e5f5

parent

9e078dc2996f93c6f864a89f5a6b1a193e6e4b19

2 files changed, 11 insertions(+), 6 deletions(-)

jump to

circuits/mimcsponge.circom

src/mimcsponge.js

M circuits/mimcsponge.circom → circuits/mimcsponge.circom

@@ -259,7 +259,7 @@ 18224457394066545825553407391290108485121649197258948320896164404518684305122,
       274945154732293792784580363548970818611304339008964723447672490026510689427,
       11050822248291117548220126630860474473945266276626263036056336623671308219529,
       2119542016932434047340813757208803962484943912710204325088879681995922344971,
-      12785816057369026966653780180257549951796705239580629452502836335892168319323
+      0
     ];
 
     var t;
@@ -276,8 +276,8 @@ if (i<nrounds-1) {
           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];
         }
     }
 }

M src/mimcsponge.js → src/mimcsponge.js

@@ -27,10 +27,11 @@ const c2 = Web3Utils.padLeft(Web3Utils.toHex(n1), 64);
         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 @@ for (let i=0; i<NROUNDS; i++) {
         const c = cts[i];
         const t = (i==0) ? F.add(xL, k) : F.add(F.add(xL, k), c);
         const xR_tmp = bigInt(xR);
-        xR = xL;
-        xL = F.add(xR_tmp, F.exp(t, 5));
+        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),