exercise merkle hashes

zksnarks/semaphore/src/merkle.js

@@ -13,3 +13,39 @@ const tree = new SMT.tree.MerkleTree(
     depth,
     default_value,
 );
+
+// tree.update(index, value)
+// tree.path(index)
+
+
+// Hash values sanity check:
+// Note that first argument to hash 'level' is ignored, has nothing to do with merkle hash.
+
+// Default:
+// zero_values:
+// [ '0',
+//   '20636625426020718969131298365984859231982649550971729229988535915544421356929',
+//   '8234632431858659206959486870703726442454087730228411315786216865106603625166' ],
+
+// > hash00 = hasher.hash(0, 0, 0).toString()
+// '20636625426020718969131298365984859231982649550971729229988535915544421356929'
+
+//     > hasher.hash(0, zero_hash, zero_hash)
+// '8234632431858659206959486870703726442454087730228411315786216865106603625166'
+// await tree.root() same
+
+
+// Add 1 value:
+//    > tree.update(1, '1')
+
+//     > hash01 = hasher.hash(0, 0, 1).toString()
+// '20817788844844400846305593449019051859483675600760331396756186604441020904869'
+
+// // Err, they reversed?
+//     > hasher.hash(0, hash00, hash01).toString()
+// '11761812633131047631528311490954788291484058935864783081603456383187402910544'
+//     > hasher.hash(0, hash01, hash00).toString()
+// '11929234368174035070205246553665882981086741604867343533563248489540467991323'
+
+// Why? Would expect: hash 0 = hash( hash 0-0 || hash 0-1 )
+// Seems like it is on purpose, oh well: https://github.com/weijiekoh/semaphore-merkle-tree/blob/master/ts/merkletree.ts#L175