path: root/src/bls.cpp

/**
    @file
    @author MITSUNARI Shigeo(@herumi)
    @license modified new BSD license
    http://opensource.org/licenses/BSD-3-Clause
*/
#include <cybozu/crypto.hpp>
#include <cybozu/random_generator.hpp>
#include <vector>
#include <string>
#include <bls/bls.hpp>
#if BLS_MAX_OP_UNIT_SIZE == 4
#include <mcl/bn256.hpp>
using namespace mcl::bn256;
#elif BLS_MAX_OP_UNIT_SIZE == 6
#include <mcl/bn384.hpp>
using namespace mcl::bn384;
#else
    #error "define BLS_MAX_OP_UNIT_SIZE 4(or 6)"
#endif

typedef std::vector<Fr> FrVec;

#define PUT(x) std::cout << #x << "=" << x << std::endl;

static cybozu::RandomGenerator& getRG()
{
    static cybozu::RandomGenerator rg;
    return rg;
}

const std::vector<Fp6> *g_pQcoeff;
const G2 *g_pQ;

namespace bls {

static const G2& getQ() { return *g_pQ; }
static const std::vector<Fp6>& getQcoeff() { return *g_pQcoeff; }

static void HashAndMapToG1(G1& P, const std::string& m)
{
    Fp t;
    t.setMsg(m);
    BN::mapToG1(P, t);
}

template<class T, class G, class Vec>
void evalPoly(G& y, const T& x, const Vec& c)
{
    if (c.size() < 2) throw cybozu::Exception("bls:evalPoly:bad size") << c.size();
    y = c[c.size() - 1];
    for (int i = (int)c.size() - 2; i >= 0; i--) {
        G::mul(y, y, x);
        G::add(y, y, c[i]);
    }
}

template<class T, class G>
struct WrapArray {
    const T *v;
    size_t k;
    WrapArray(const T *v, size_t k) : v(v), k(k) {}
    const G& operator[](size_t i) const
    {
        return v[i].getInner().get();
    }
    size_t size() const { return k; }
};

struct Polynomial {
    FrVec c; // f[x] = sum_{i=0}^{k-1} c[i] x^i
    void init(const Fr& s, int k)
    {
        if (k < 2) throw cybozu::Exception("bls:Polynomial:init:bad k") << k;
        c.resize(k);
        c[0] = s;
        for (size_t i = 1; i < c.size(); i++) {
            c[i].setRand(getRG());
        }
    }
    // y = f(id)
    void eval(Fr& y, const Fr& id) const
    {
        if (id.isZero()) throw cybozu::Exception("bls:Polynomial:eval:id is zero");
        evalPoly(y, id, c);
    }
};

namespace impl {

struct Id {
    Fr v;
    const Fr& get() const { return v; }
};

struct SecretKey {
    Fr s;
    const Fr& get() const { return s; }
};

struct Signature {
    G1 sHm; // s Hash(m)
    const G1& get() const { return sHm; }
};

struct PublicKey {
    G2 sQ;
    const G2& get() const { return sQ; }
    void getStr(std::string& str) const
    {
        sQ.getStr(str, mcl::IoArrayRaw);
    }
};

} // mcl::bls::impl

/*
    recover f(0) by { (x, y) | x = S[i], y = f(x) = vec[i] }
*/
template<class G, class V1, class V2>
void LagrangeInterpolation(G& r, const V1& vec, const V2& S)
{
    /*
        delta_{i,S}(0) = prod_{j != i} S[j] / (S[j] - S[i]) = a / b
        where a = prod S[j], b = S[i] * prod_{j != i} (S[j] - S[i])
    */
    const size_t k = S.size();
    if (vec.size() != k) throw cybozu::Exception("bls:LagrangeInterpolation:bad size") << vec.size() << k;
    if (k < 2) throw cybozu::Exception("bls:LagrangeInterpolation:too small size") << k;
    FrVec delta(k);
    Fr a = S[0];
    for (size_t i = 1; i < k; i++) {
        a *= S[i];
    }
    for (size_t i = 0; i < k; i++) {
        Fr b = S[i];
        for (size_t j = 0; j < k; j++) {
            if (j != i) {
                Fr v = S[j] - S[i];
                if (v.isZero()) throw cybozu::Exception("bls:LagrangeInterpolation:S has same id") << i << j;
                b *= v;
            }
        }
        delta[i] = a / b;
    }

    /*
        f(0) = sum_i f(S[i]) delta_{i,S}(0)
    */
    r.clear();
    G t;
    for (size_t i = 0; i < delta.size(); i++) {
        G::mul(t, vec[i], delta[i]);
        r += t;
    }
}

template<class T>
std::ostream& writeAsHex(std::ostream& os, const T& t)
{
    std::string str;
    t.getStr(str, mcl::IoHexPrefix);
    return os << str;
}

void init(int curve, int maxUnitSize)
{
    if (maxUnitSize != BLS_MAX_OP_UNIT_SIZE) throw cybozu::Exception("bls:init:bad maxUnitSize") << maxUnitSize << BLS_MAX_OP_UNIT_SIZE;
    mcl::bn::CurveParam cp;
    switch (curve) {
    case bls::CurveFp254BNb:
        cp = mcl::bn::CurveFp254BNb;
        break;
#if BLS_MAX_OP_UNIT_SIZE == 6
    case bls::CurveFp382_1:
        cp = mcl::bn::CurveFp382_1;
        break;
    case bls::CurveFp382_2:
        cp = mcl::bn::CurveFp382_2;
        break;
#endif
    default:
        throw cybozu::Exception("bls:init:bad curve") << curve;
    }
    BN::init(cp);
    G1::setCompressedExpression();
    G2::setCompressedExpression();
    Fr::init(BN::param.r);
//  mcl::setIoMode(mcl::IoHeximal);
    assert(sizeof(Id) == sizeof(impl::Id));
    assert(sizeof(SecretKey) == sizeof(impl::SecretKey));
    assert(sizeof(PublicKey) == sizeof(impl::PublicKey));
    assert(sizeof(Signature) == sizeof(impl::Signature));
    static G2 Q;
    if (curve == bls::CurveFp254BNb) {
        Q.set(
            Fp2("12723517038133731887338407189719511622662176727675373276651903807414909099441", "4168783608814932154536427934509895782246573715297911553964171371032945126671"),
            Fp2("13891744915211034074451795021214165905772212241412891944830863846330766296736", "7937318970632701341203597196594272556916396164729705624521405069090520231616")
        );
    } else {
        BN::mapToG2(Q, 1);
    }
    static std::vector<Fp6> Qcoeff;

    BN::precomputeG2(Qcoeff, Q);
    g_pQ = &Q;
    g_pQcoeff = &Qcoeff;
}
size_t getOpUnitSize()
{
    return Fp::getUnitSize() * sizeof(mcl::fp::Unit) / sizeof(uint64_t);
}

void getCurveOrder(std::string& str)
{
    Fr::getModulo(str);
}
void getFieldOrder(std::string& str)
{
    Fp::getModulo(str);
}

Id::Id(unsigned int id)
{
    getInner().v = id;
}

bool Id::operator==(const Id& rhs) const
{
    return getInner().v == rhs.getInner().v;
}

std::ostream& operator<<(std::ostream& os, const Id& id)
{
    return writeAsHex(os, id.getInner().v);
}

std::istream& operator>>(std::istream& is, Id& id)
{
    return is >> id.getInner().v;
}
void Id::getStr(std::string& str, int ioMode) const
{
    getInner().v.getStr(str, ioMode);
}
void Id::setStr(const std::string& str, int ioMode)
{
    getInner().v.setStr(str, ioMode);
}

bool Id::isZero() const
{
    return getInner().v.isZero();
}

void Id::set(const uint64_t *p)
{
    getInner().v.setArrayMask(p, keySize);
}

void Id::setLittleEndian(const void *buf, size_t bufSize)
{
    getInner().v.setArrayMask((const char *)buf, bufSize);
}

bool Signature::operator==(const Signature& rhs) const
{
    return getInner().sHm == rhs.getInner().sHm;
}

std::ostream& operator<<(std::ostream& os, const Signature& s)
{
    return writeAsHex(os, s.getInner().sHm);
}

std::istream& operator>>(std::istream& os, Signature& s)
{
    return os >> s.getInner().sHm;
}
void Signature::getStr(std::string& str, int ioMode) const
{
    getInner().sHm.getStr(str, ioMode);
}
void Signature::setStr(const std::string& str, int ioMode)
{
    getInner().sHm.setStr(str, ioMode);
}

bool Signature::verify(const PublicKey& pub, const std::string& m) const
{
    G1 Hm;
    HashAndMapToG1(Hm, m); // Hm = Hash(m)
#if 1
    /*
        e(P1, Q1) == e(P2, Q2)
        <=> finalExp(ML(P1, Q1)) == finalExp(ML(P2, Q2))
        <=> finalExp(ML(P1, Q1) / ML(P2, Q2)) == 1
        <=> finalExp(ML(P1, Q1) * ML(-P2, Q2)) == 1
        2.1Mclk => 1.5Mclk
    */
    Fp12 e;
    std::vector<Fp6> Q2coeff;
    BN::precomputeG2(Q2coeff, pub.getInner().sQ);
    BN::precomputedMillerLoop2(e, getInner().sHm, getQcoeff(), -Hm, Q2coeff);
    BN::finalExp(e, e);
    return e.isOne();
#else
    Fp12 e1, e2;
    BN::pairing(e1, getInner().sHm, getQ()); // e(s Hm, Q)
    BN::pairing(e2, Hm, pub.getInner().sQ); // e(Hm, sQ)
    return e1 == e2;
#endif
}

bool Signature::verify(const PublicKey& pub) const
{
    std::string str;
    pub.getInner().sQ.getStr(str);
    return verify(pub, str);
}

void Signature::recover(const SignatureVec& sigVec, const IdVec& idVec)
{
    if (sigVec.size() != idVec.size()) throw cybozu::Exception("Signature:recover:bad size") << sigVec.size() << idVec.size();
    recover(sigVec.data(), idVec.data(), sigVec.size());
}

void Signature::recover(const Signature* sigVec, const Id *idVec, size_t n)
{
    WrapArray<Signature, G1> signW(sigVec, n);
    WrapArray<Id, Fr> idW(idVec, n);
    LagrangeInterpolation(getInner().sHm, signW, idW);
}

void Signature::add(const Signature& rhs)
{
    getInner().sHm += rhs.getInner().sHm;
}

bool PublicKey::operator==(const PublicKey& rhs) const
{
    return getInner().sQ == rhs.getInner().sQ;
}

std::ostream& operator<<(std::ostream& os, const PublicKey& pub)
{
    return writeAsHex(os, pub.getInner().sQ);
}

std::istream& operator>>(std::istream& is, PublicKey& pub)
{
    return is >> pub.getInner().sQ;
}

void PublicKey::getStr(std::string& str, int ioMode) const
{
    getInner().sQ.getStr(str, ioMode);
}
void PublicKey::setStr(const std::string& str, int ioMode)
{
    getInner().sQ.setStr(str, ioMode);
}
void PublicKey::set(const PublicKey *mpk, size_t k, const Id& id)
{
    WrapArray<PublicKey, G2> w(mpk, k);
    evalPoly(getInner().sQ, id.getInner().v, w);
}

void PublicKey::recover(const PublicKeyVec& pubVec, const IdVec& idVec)
{
    if (pubVec.size() != idVec.size()) throw cybozu::Exception("PublicKey:recover:bad size") << pubVec.size() << idVec.size();
    recover(pubVec.data(), idVec.data(), pubVec.size());
}
void PublicKey::recover(const PublicKey *pubVec, const Id *idVec, size_t n)
{
    WrapArray<PublicKey, G2> pubW(pubVec, n);
    WrapArray<Id, Fr> idW(idVec, n);
    LagrangeInterpolation(getInner().sQ, pubW, idW);
}

void PublicKey::add(const PublicKey& rhs)
{
    getInner().sQ += rhs.getInner().sQ;
}

bool SecretKey::operator==(const SecretKey& rhs) const
{
    return getInner().s == rhs.getInner().s;
}

std::ostream& operator<<(std::ostream& os, const SecretKey& sec)
{
    return writeAsHex(os, sec.getInner().s);
}

std::istream& operator>>(std::istream& is, SecretKey& sec)
{
    return is >> sec.getInner().s;
}
void SecretKey::getStr(std::string& str, int ioMode) const
{
    getInner().s.getStr(str, ioMode);
}
void SecretKey::setStr(const std::string& str, int ioMode)
{
    getInner().s.setStr(str, ioMode);
}

void SecretKey::init()
{
    getInner().s.setRand(getRG());
}

void SecretKey::set(const uint64_t *p)
{
    getInner().s.setArrayMask(p, keySize);
}
void SecretKey::setLittleEndian(const void *buf, size_t bufSize)
{
    getInner().s.setArrayMask((const char *)buf, bufSize);
}

void SecretKey::getPublicKey(PublicKey& pub) const
{
    G2::mul(pub.getInner().sQ, getQ(), getInner().s);
}

void SecretKey::sign(Signature& sig, const std::string& m) const
{
    G1 Hm;
    HashAndMapToG1(Hm, m);
//  G1::mul(sig.getInner().sHm, Hm, getInner().s);
    G1::mulCT(sig.getInner().sHm, Hm, getInner().s);
}

void SecretKey::getPop(Signature& pop) const
{
    PublicKey pub;
    getPublicKey(pub);
    std::string m;
    pub.getInner().sQ.getStr(m);
    sign(pop, m);
}

void SecretKey::getMasterSecretKey(SecretKeyVec& msk, size_t k) const
{
    if (k <= 1) throw cybozu::Exception("bls:SecretKey:getMasterSecretKey:bad k") << k;
    msk.resize(k);
    msk[0] = *this;
    for (size_t i = 1; i < k; i++) {
        msk[i].init();
    }
}

void SecretKey::set(const SecretKey *msk, size_t k, const Id& id)
{
    WrapArray<SecretKey, Fr> w(msk, k);
    evalPoly(getInner().s, id.getInner().v, w);
}

void SecretKey::recover(const SecretKeyVec& secVec, const IdVec& idVec)
{
    if (secVec.size() != idVec.size()) throw cybozu::Exception("SecretKey:recover:bad size") << secVec.size() << idVec.size();
    recover(secVec.data(), idVec.data(), secVec.size());
}
void SecretKey::recover(const SecretKey *secVec, const Id *idVec, size_t n)
{
    WrapArray<SecretKey, Fr> secW(secVec, n);
    WrapArray<Id, Fr> idW(idVec, n);
    LagrangeInterpolation(getInner().s, secW, idW);
}

void SecretKey::add(const SecretKey& rhs)
{
    getInner().s += rhs.getInner().s;
}

} // bls