1const createBlakeHash = require("blake-hash");
  2const bigInt = require("snarkjs").bigInt;
  3const babyJub = require("./babyjub");
  4const pedersenHash = require("./pedersenHash").hash;
  5const mimc7 = require("./mimc7");
  6const crypto = require("crypto");
  7    
  8exports.cratePrvKey = cratePrvKey;
  9exports.prv2pub= prv2pub;
 10exports.sign = sign;
 11exports.signMiMC = signMiMC;
 12exports.verify = verify;
 13exports.verifyMiMC = verifyMiMC;
 14exports.packSignature = packSignature;
 15exports.unpackSignature = unpackSignature;
 16exports.pruneBuffer = pruneBuffer;
 17
 18
 19function cratePrvKey() {
 20    return crypto.randomBytes(32);
 21}
 22
 23function pruneBuffer(_buff) {
 24    const buff = Buffer.from(_buff);
 25    buff[0] = buff[0] & 0xF8;
 26    buff[31] = buff[31] & 0x7F;
 27    buff[31] = buff[31] | 0x40;
 28    return buff;
 29}
 30
 31function prv2pub(prv) {
 32    const sBuff = pruneBuffer(createBlakeHash("blake512").update(prv).digest().slice(0,32));
 33    let s = bigInt.leBuff2int(sBuff);
 34    const A = babyJub.mulPointEscalar(babyJub.Base8, s.shr(3));
 35    return A;
 36}
 37
 38function sign(prv, msg) {
 39    const h1 = createBlakeHash("blake512").update(prv).digest();
 40    const sBuff = pruneBuffer(h1.slice(0,32));
 41    const s = bigInt.leBuff2int(sBuff);
 42    const A = babyJub.mulPointEscalar(babyJub.Base8, s.shr(3));
 43
 44    const rBuff = createBlakeHash("blake512").update(Buffer.concat([h1.slice(32,64), msg])).digest();
 45    let r = bigInt.leBuff2int(rBuff);
 46    r = r.mod(babyJub.subOrder);
 47    const R8 = babyJub.mulPointEscalar(babyJub.Base8, r);
 48    const R8p = babyJub.packPoint(R8);
 49    const Ap = babyJub.packPoint(A);
 50    const hmBuff = pedersenHash(Buffer.concat([R8p, Ap, msg]));
 51    const hm = bigInt.leBuff2int(hmBuff);
 52    const S = r.add(hm.mul(s)).mod(babyJub.subOrder);
 53    return {
 54        R8: R8,
 55        S: S
 56    };
 57}
 58
 59function signMiMC(prv, msg) {
 60    const h1 = createBlakeHash("blake512").update(prv).digest();
 61    const sBuff = pruneBuffer(h1.slice(0,32));
 62    const s = bigInt.leBuff2int(sBuff);
 63    const A = babyJub.mulPointEscalar(babyJub.Base8, s.shr(3));
 64
 65    const msgBuff = bigInt.leInt2Buff(msg, 32);
 66    const rBuff = createBlakeHash("blake512").update(Buffer.concat([h1.slice(32,64), msgBuff])).digest();
 67    let r = bigInt.leBuff2int(rBuff);
 68    r = r.mod(babyJub.subOrder);
 69    const R8 = babyJub.mulPointEscalar(babyJub.Base8, r);
 70    const hm = mimc7.multiHash([R8[0], R8[1], A[0], A[1], msg]);
 71    const S = r.add(hm.mul(s)).mod(babyJub.subOrder);
 72    return {
 73        R8: R8,
 74        S: S
 75    };
 76}
 77
 78function verify(msg, sig, A) {
 79    // Check parameters
 80    if (typeof sig != "object") return false;
 81    if (!Array.isArray(sig.R8)) return false;
 82    if (sig.R8.length!= 2) return false;
 83    if (!babyJub.inCurve(sig.R8)) return false;
 84    if (!Array.isArray(A)) return false;
 85    if (A.length!= 2) return false;
 86    if (!babyJub.inCurve(A)) return false;
 87    if (sig.S>= babyJub.subOrder) return false;
 88
 89    const R8p = babyJub.packPoint(sig.R8);
 90    const Ap = babyJub.packPoint(A);
 91    const hmBuff = pedersenHash(Buffer.concat([R8p, Ap, msg]));
 92    const hm = bigInt.leBuff2int(hmBuff);
 93
 94    const Pleft = babyJub.mulPointEscalar(babyJub.Base8, sig.S);
 95    let Pright = babyJub.mulPointEscalar(A, hm.mul(bigInt("8")));
 96    Pright = babyJub.addPoint(sig.R8, Pright);
 97
 98    if (!Pleft[0].equals(Pright[0])) return false;
 99    if (!Pleft[1].equals(Pright[1])) return false;
100    return true;
101}
102
103function verifyMiMC(msg, sig, A) {
104    // Check parameters
105    if (typeof sig != "object") return false;
106    if (!Array.isArray(sig.R8)) return false;
107    if (sig.R8.length!= 2) return false;
108    if (!babyJub.inCurve(sig.R8)) return false;
109    if (!Array.isArray(A)) return false;
110    if (A.length!= 2) return false;
111    if (!babyJub.inCurve(A)) return false;
112    if (sig.S>= babyJub.subOrder) return false;
113
114    const hm = mimc7.multiHash([sig.R8[0], sig.R8[1], A[0], A[1], msg]);
115
116    const Pleft = babyJub.mulPointEscalar(babyJub.Base8, sig.S);
117    let Pright = babyJub.mulPointEscalar(A, hm.mul(bigInt("8")));
118    Pright = babyJub.addPoint(sig.R8, Pright);
119
120    if (!Pleft[0].equals(Pright[0])) return false;
121    if (!Pleft[1].equals(Pright[1])) return false;
122    return true;
123}
124
125function packSignature(sig) {
126    const R8p = babyJub.packPoint(sig.R8);
127    const Sp = bigInt.leInt2Buff(sig.S, 32);
128    return Buffer.concat([R8p, Sp]);
129}
130
131function unpackSignature(sigBuff) {
132    return {
133        R8: babyJub.unpackPoint(sigBuff.slice(0,32)),
134        S: bigInt.leBuff2int(sigBuff.slice(32,64))
135    };
136}
137
138