feat: add MiMC implementation

.github/NIGHTLY_CANARY_DIED.md

@@ -1,7 +1,8 @@
 ---
 title: "Tests fail on latest Nargo nightly release"
+assignees: TomAFrench
 ---
 
 The tests on this Noir project have started failing when using the latest nightly release of the Noir compiler. This likely means that there have been breaking changes for which this project needs to be updated to take into account.
 
-Check the [{{env.WORKFLOW_NAME}}]({{env.WORKFLOW_URL}}) workflow for details.
+Check the [{{env.WORKFLOW_NAME}}]({{env.WORKFLOW_URL}}) workflow for details.

Nargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "noir_library"
+name = "mimc"
 type = "lib"
 authors = [""]
 compiler_version = ">=0.34.0"

README.md

@@ -1,20 +1,7 @@
-# noir-library-starter
 
-This repository is a template used by the noir-lang org when creating internally maintained libraries.
+# MiMC
 
-This provides out of the box:
-
-- A simple CI setup to test and format the library
-- A canary flagging up compilation failures on nightly releases.
-- A [release-please](https://github.com/googleapis/release-please) setup to ease creating releases for the library.
-
-Feel free to use this template as a starting point to create your own Noir libraries.
-
----
-
-# LIBRARY_NAME
-
-Add a brief description of the library
+A Noir implementation of the MiMC hash function.
 
 ## Benchmarks
 
@@ -27,11 +14,5 @@ In your _Nargo.toml_ file, add the version of this library you would like to ins
 
 ```
 [dependencies]
-LIBRARY = { tag = "v0.1.0", git = "https://github.com/noir-lang/LIBRARY_NAME" }
+mimc = { tag = "v0.1.0", git = "https://github.com/noir-lang/mimc" }
 ```
-
-## `library`
-
-### Usage
-
-`PLACEHOLDER`

src/lib.nr

@@ -1,5 +1,165 @@
-/// This doesn't really do anything by ensures that there is a test for CI to run.
-#[test]
-fn smoke_test() {
-    assert(true);
+use std::hash::Hasher;
+use std::default::Default;
+
+// mimc-p/p implementation
+// constants are (publicly generated) random numbers, for instance using keccak as a ROM.
+// You must use constants generated for the native field
+// Rounds number should be ~ log(p)/log(exp)
+// For 254 bit primes, exponent 7 and 91 rounds seems to be recommended
+pub fn mimc<let N: u32>(x: Field, k: Field, constants: [Field; N], exp: Field) -> Field {
+    //round 0
+    let mut t = x + k;
+    let mut h = t.pow_32(exp);
+    //next rounds
+    for i in 1..constants.len() {
+        t = h + k + constants[i];
+        h = t.pow_32(exp);
+    }
+    h + k
+}
+
+global MIMC_BN254_ROUNDS: u32 = 91;
+//generated from seed "mimc" using keccak256 
+global MIMC_BN254_CONSTANTS: [Field; MIMC_BN254_ROUNDS] = [
+        0,
+        20888961410941983456478427210666206549300505294776164667214940546594746570981,
+        15265126113435022738560151911929040668591755459209400716467504685752745317193,
+        8334177627492981984476504167502758309043212251641796197711684499645635709656,
+        1374324219480165500871639364801692115397519265181803854177629327624133579404,
+        11442588683664344394633565859260176446561886575962616332903193988751292992472,
+        2558901189096558760448896669327086721003508630712968559048179091037845349145,
+        11189978595292752354820141775598510151189959177917284797737745690127318076389,
+        3262966573163560839685415914157855077211340576201936620532175028036746741754,
+        17029914891543225301403832095880481731551830725367286980611178737703889171730,
+        4614037031668406927330683909387957156531244689520944789503628527855167665518,
+        19647356996769918391113967168615123299113119185942498194367262335168397100658,
+        5040699236106090655289931820723926657076483236860546282406111821875672148900,
+        2632385916954580941368956176626336146806721642583847728103570779270161510514,
+        17691411851977575435597871505860208507285462834710151833948561098560743654671,
+        11482807709115676646560379017491661435505951727793345550942389701970904563183,
+        8360838254132998143349158726141014535383109403565779450210746881879715734773,
+        12663821244032248511491386323242575231591777785787269938928497649288048289525,
+        3067001377342968891237590775929219083706800062321980129409398033259904188058,
+        8536471869378957766675292398190944925664113548202769136103887479787957959589,
+        19825444354178182240559170937204690272111734703605805530888940813160705385792,
+        16703465144013840124940690347975638755097486902749048533167980887413919317592,
+        13061236261277650370863439564453267964462486225679643020432589226741411380501,
+        10864774797625152707517901967943775867717907803542223029967000416969007792571,
+        10035653564014594269791753415727486340557376923045841607746250017541686319774,
+        3446968588058668564420958894889124905706353937375068998436129414772610003289,
+        4653317306466493184743870159523234588955994456998076243468148492375236846006,
+        8486711143589723036499933521576871883500223198263343024003617825616410932026,
+        250710584458582618659378487568129931785810765264752039738223488321597070280,
+        2104159799604932521291371026105311735948154964200596636974609406977292675173,
+        16313562605837709339799839901240652934758303521543693857533755376563489378839,
+        6032365105133504724925793806318578936233045029919447519826248813478479197288,
+        14025118133847866722315446277964222215118620050302054655768867040006542798474,
+        7400123822125662712777833064081316757896757785777291653271747396958201309118,
+        1744432620323851751204287974553233986555641872755053103823939564833813704825,
+        8316378125659383262515151597439205374263247719876250938893842106722210729522,
+        6739722627047123650704294650168547689199576889424317598327664349670094847386,
+        21211457866117465531949733809706514799713333930924902519246949506964470524162,
+        13718112532745211817410303291774369209520657938741992779396229864894885156527,
+        5264534817993325015357427094323255342713527811596856940387954546330728068658,
+        18884137497114307927425084003812022333609937761793387700010402412840002189451,
+        5148596049900083984813839872929010525572543381981952060869301611018636120248,
+        19799686398774806587970184652860783461860993790013219899147141137827718662674,
+        19240878651604412704364448729659032944342952609050243268894572835672205984837,
+        10546185249390392695582524554167530669949955276893453512788278945742408153192,
+        5507959600969845538113649209272736011390582494851145043668969080335346810411,
+        18177751737739153338153217698774510185696788019377850245260475034576050820091,
+        19603444733183990109492724100282114612026332366576932662794133334264283907557,
+        10548274686824425401349248282213580046351514091431715597441736281987273193140,
+        1823201861560942974198127384034483127920205835821334101215923769688644479957,
+        11867589662193422187545516240823411225342068709600734253659804646934346124945,
+        18718569356736340558616379408444812528964066420519677106145092918482774343613,
+        10530777752259630125564678480897857853807637120039176813174150229243735996839,
+        20486583726592018813337145844457018474256372770211860618687961310422228379031,
+        12690713110714036569415168795200156516217175005650145422920562694422306200486,
+        17386427286863519095301372413760745749282643730629659997153085139065756667205,
+        2216432659854733047132347621569505613620980842043977268828076165669557467682,
+        6309765381643925252238633914530877025934201680691496500372265330505506717193,
+        20806323192073945401862788605803131761175139076694468214027227878952047793390,
+        4037040458505567977365391535756875199663510397600316887746139396052445718861,
+        19948974083684238245321361840704327952464170097132407924861169241740046562673,
+        845322671528508199439318170916419179535949348988022948153107378280175750024,
+        16222384601744433420585982239113457177459602187868460608565289920306145389382,
+        10232118865851112229330353999139005145127746617219324244541194256766741433339,
+        6699067738555349409504843460654299019000594109597429103342076743347235369120,
+        6220784880752427143725783746407285094967584864656399181815603544365010379208,
+        6129250029437675212264306655559561251995722990149771051304736001195288083309,
+        10773245783118750721454994239248013870822765715268323522295722350908043393604,
+        4490242021765793917495398271905043433053432245571325177153467194570741607167,
+        19596995117319480189066041930051006586888908165330319666010398892494684778526,
+        837850695495734270707668553360118467905109360511302468085569220634750561083,
+        11803922811376367215191737026157445294481406304781326649717082177394185903907,
+        10201298324909697255105265958780781450978049256931478989759448189112393506592,
+        13564695482314888817576351063608519127702411536552857463682060761575100923924,
+        9262808208636973454201420823766139682381973240743541030659775288508921362724,
+        173271062536305557219323722062711383294158572562695717740068656098441040230,
+        18120430890549410286417591505529104700901943324772175772035648111937818237369,
+        20484495168135072493552514219686101965206843697794133766912991150184337935627,
+        19155651295705203459475805213866664350848604323501251939850063308319753686505,
+        11971299749478202793661982361798418342615500543489781306376058267926437157297,
+        18285310723116790056148596536349375622245669010373674803854111592441823052978,
+        7069216248902547653615508023941692395371990416048967468982099270925308100727,
+        6465151453746412132599596984628739550147379072443683076388208843341824127379,
+        16143532858389170960690347742477978826830511669766530042104134302796355145785,
+        19362583304414853660976404410208489566967618125972377176980367224623492419647,
+        1702213613534733786921602839210290505213503664731919006932367875629005980493,
+        10781825404476535814285389902565833897646945212027592373510689209734812292327,
+        4212716923652881254737947578600828255798948993302968210248673545442808456151,
+        7594017890037021425366623750593200398174488805473151513558919864633711506220,
+        18979889247746272055963929241596362599320706910852082477600815822482192194401,
+        13602139229813231349386885113156901793661719180900395818909719758150455500533
+    ];
+
+//mimc implementation with hardcoded parameters for BN254 curve.
+#[field(bn254)]
+pub fn mimc_bn254<let N: u32>(array: [Field; N]) -> Field {
+    let exponent = 7;
+    let mut r = 0;
+    for elem in array {
+        let h = mimc(elem, r, MIMC_BN254_CONSTANTS, exponent);
+        r = r + elem + h;
+    }
+    r
+}
+
+pub struct MimcHasher {
+    _state: [Field],
+}
+
+impl Hasher for MimcHasher {
+    #[field(bn254)]
+    fn finish(self) -> Field {
+        let exponent = 7;
+        let mut r = 0;
+        for i in 0..self._state.len() {
+            let h = mimc(self._state[i], r, MIMC_BN254_CONSTANTS, exponent);
+            r = r + self._state[i] + h;
+        }
+        r
+    }
+
+    fn write(&mut self, input: Field) {
+        self._state = self._state.push_back(input);
+    }
+}
+
+impl Default for MimcHasher {
+    fn default() -> Self {
+        MimcHasher { _state: &[] }
+    }
+}
+
+mod tests {
+    use super::mimc_bn254;
+
+    #[test]
+    fn smoke_test() {
+        let input = [12, 45, 78, 41];
+        let expected_output = 18226366069841799622585958305961373004333097209608110160936134895615261821931;
+        assert_eq(mimc_bn254(input), expected_output);
+    }
 }