bignum.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2012 The Bitcoin developers
// Copyright (c) 2015-2018 The PIVX developers
// Copyright (c) 2018-2020 The DAPS Project developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_BIGNUM_H
#define BITCOIN_BIGNUM_H
 
#include <stdexcept>
#include <vector>
#include <openssl/bn.h>
#include "serialize.h"
#include "uint256.h"
#include "version.h"
 
class bignum_error : public std::runtime_error
{
public:
    explicit bignum_error(const std::string& str) : std::runtime_error(str) {}
};
 
 
class CAutoBN_CTX
{
protected:
    BN_CTX* pctx;
    BN_CTX* operator=(BN_CTX* pnew) { return pctx = pnew; }
 
public:
    CAutoBN_CTX()
    {
        pctx = BN_CTX_new();
        if (pctx == NULL)
            throw bignum_error("CAutoBN_CTX : BN_CTX_new() returned NULL");
    }
 
    ~CAutoBN_CTX()
    {
        if (pctx != NULL)
            BN_CTX_free(pctx);
    }
 
    operator BN_CTX*() { return pctx; }
    BN_CTX& operator*() { return *pctx; }
    BN_CTX** operator&() { return &pctx; }
    bool operator!() { return (pctx == NULL); }
};
 
 
class CBigNum
{
    BIGNUM* bn;
public:
    CBigNum()
    {
        bn = BN_new();
    }
 
    // Initialize from a Hex String
    CBigNum(const std::string& str) {
        bn = BN_new();
        SetHexBool(str);
    }
 
 
    CBigNum(const CBigNum& b)
    {
        bn = BN_new();
        if (!BN_copy(bn, b.bn))
        {
            BN_clear_free(bn);
            throw bignum_error("CBigNum::CBigNum(const CBigNum&) : BN_copy failed");
        }
    }
 
    CBigNum& operator=(const CBigNum& b)
    {
        if (!BN_copy(bn, b.bn))
            throw bignum_error("CBigNum::operator= : BN_copy failed");
        return (*this);
    }
 
    ~CBigNum()
    {
        BN_clear_free(bn);
    }
 
    //CBigNum(char n) is not portable.  Use 'signed char' or 'unsigned char'.
    CBigNum(signed char n)      { bn = BN_new(); if (n >= 0) setulong(n); else setint64(n); }
    CBigNum(short n)            { bn = BN_new(); if (n >= 0) setulong(n); else setint64(n); }
    CBigNum(int n)              { bn = BN_new(); if (n >= 0) setulong(n); else setint64(n); }
    CBigNum(long n)             { bn = BN_new(); if (n >= 0) setulong(n); else setint64(n); }
#ifdef __APPLE__
    CBigNum(int64_t n)            { bn = BN_new(); setint64(n); }
#endif
    CBigNum(unsigned char n)    { bn = BN_new(); setulong(n); }
    CBigNum(unsigned short n)   { bn = BN_new(); setulong(n); }
    CBigNum(unsigned int n)     { bn = BN_new(); setulong(n); }
    CBigNum(unsigned long n)    { bn = BN_new(); setulong(n); }
  //  CBigNum(uint64_t n)           { bn = BN_new(); setuint64(n); }
    explicit CBigNum(uint256 n) { bn = BN_new(); setuint256(n); }
 
    explicit CBigNum(const std::vector<unsigned char>& vch)
    {
        bn = BN_new();
        setvch(vch);
    }
 
    static CBigNum  randBignum(const CBigNum& range) {
        CBigNum ret;
        if(!BN_rand_range(ret.bn, range.bn)){
            throw bignum_error("CBigNum:rand element : BN_rand_range failed");
        }
        return ret;
    }
 
    static CBigNum RandKBitBigum(const uint32_t k){
        CBigNum ret;
        if(!BN_rand(ret.bn, k, -1, 0)){
            throw bignum_error("CBigNum:rand element : BN_rand failed");
        }
        return ret;
    }
 
    int bitSize() const{
        return  BN_num_bits(bn);
    }
 
    void setulong(unsigned long n)
    {
        if (!BN_set_word(bn, n))
            throw bignum_error("CBigNum conversion from unsigned long : BN_set_word failed");
    }
 
    unsigned long getulong() const
    {
        return BN_get_word(bn);
    }
 
    unsigned int getuint() const
    {
        return BN_get_word(bn);
    }
 
    int getint() const
    {
        unsigned long n = BN_get_word(bn);
        if (!BN_is_negative(bn))
            return (n > (unsigned long)std::numeric_limits<int>::max() ? std::numeric_limits<int>::max() : n);
        else
            return (n > (unsigned long)std::numeric_limits<int>::max() ? std::numeric_limits<int>::min() : -(int)n);
    }
 
    void setint64(int64_t sn)
    {
        unsigned char pch[sizeof(sn) + 6];
        unsigned char* p = pch + 4;
        bool fNegative;
        uint64_t n;
 
        if (sn < (int64_t)0)
        {
            // Since the minimum signed integer cannot be represented as positive so long as its type is signed,
            // and it's not well-defined what happens if you make it unsigned before negating it,
            // we instead increment the negative integer by 1, convert it, then increment the (now positive) unsigned integer by 1 to compensate
            n = -(sn + 1);
            ++n;
            fNegative = true;
        } else {
            n = sn;
            fNegative = false;
        }
 
        bool fLeadingZeroes = true;
        for (int i = 0; i < 8; i++)
        {
            unsigned char c = (n >> 56) & 0xff;
            n <<= 8;
            if (fLeadingZeroes)
            {
                if (c == 0)
                    continue;
                if (c & 0x80)
                    *p++ = (fNegative ? 0x80 : 0);
                else if (fNegative)
                    c |= 0x80;
                fLeadingZeroes = false;
            }
            *p++ = c;
        }
        unsigned int nSize = p - (pch + 4);
        pch[0] = (nSize >> 24) & 0xff;
        pch[1] = (nSize >> 16) & 0xff;
        pch[2] = (nSize >> 8) & 0xff;
        pch[3] = (nSize) & 0xff;
        BN_mpi2bn(pch, p - pch, bn);
    }
 
    void setuint64(uint64_t n)
    {
        unsigned char pch[sizeof(n) + 6];
        unsigned char* p = pch + 4;
        bool fLeadingZeroes = true;
        for (int i = 0; i < 8; i++)
        {
            unsigned char c = (n >> 56) & 0xff;
            n <<= 8;
            if (fLeadingZeroes)
            {
                if (c == 0)
                    continue;
                if (c & 0x80)
                    *p++ = 0;
                fLeadingZeroes = false;
            }
            *p++ = c;
        }
        unsigned int nSize = p - (pch + 4);
        pch[0] = (nSize >> 24) & 0xff;
        pch[1] = (nSize >> 16) & 0xff;
        pch[2] = (nSize >> 8) & 0xff;
        pch[3] = (nSize) & 0xff;
        BN_mpi2bn(pch, p - pch, bn);
    }
 
    void setuint256(uint256 n)
    {
        unsigned char pch[sizeof(n) + 6];
        unsigned char* p = pch + 4;
        bool fLeadingZeroes = true;
        unsigned char* pbegin = (unsigned char*)&n;
        unsigned char* psrc = pbegin + sizeof(n);
        while (psrc != pbegin)
        {
            unsigned char c = *(--psrc);
            if (fLeadingZeroes)
            {
                if (c == 0)
                    continue;
                if (c & 0x80)
                    *p++ = 0;
                fLeadingZeroes = false;
            }
            *p++ = c;
        }
        unsigned int nSize = p - (pch + 4);
        pch[0] = (nSize >> 24) & 0xff;
        pch[1] = (nSize >> 16) & 0xff;
        pch[2] = (nSize >> 8) & 0xff;
        pch[3] = (nSize >> 0) & 0xff;
        BN_mpi2bn(pch, p - pch, bn);
    }
 
    uint256 getuint256() const
    {
        unsigned int nSize = BN_bn2mpi(bn, NULL);
        if (nSize < 4)
            return 0;
        std::vector<unsigned char> vch(nSize);
        BN_bn2mpi(bn, &vch[0]);
        if (vch.size() > 4)
            vch[4] &= 0x7f;
        uint256 n = 0;
        for (unsigned int i = 0, j = vch.size()-1; i < sizeof(n) && j >= 4; i++, j--)
            ((unsigned char*)&n)[i] = vch[j];
        return n;
    }
 
    void setvch(const std::vector<unsigned char>& vch)
    {
        std::vector<unsigned char> vch2(vch.size() + 4);
        unsigned int nSize = vch.size();
        // BIGNUM's byte stream format expects 4 bytes of
        // big endian size data info at the front
        vch2[0] = (nSize >> 24) & 0xff;
        vch2[1] = (nSize >> 16) & 0xff;
        vch2[2] = (nSize >> 8) & 0xff;
        vch2[3] = (nSize >> 0) & 0xff;
        // swap data to big endian
        reverse_copy(vch.begin(), vch.end(), vch2.begin() + 4);
        BN_mpi2bn(&vch2[0], vch2.size(), bn);
    }
 
    std::vector<unsigned char> getvch() const
    {
        unsigned int nSize = BN_bn2mpi(bn, NULL);
        if (nSize <= 4)
            return std::vector<unsigned char>();
        std::vector<unsigned char> vch(nSize);
        BN_bn2mpi(bn, &vch[0]);
        vch.erase(vch.begin(), vch.begin() + 4);
        reverse(vch.begin(), vch.end());
        return vch;
    }
 
    // The "compact" format is a representation of a whole
    // number N using an unsigned 32bit number similar to a
    // floating point format.
    // The most significant 8 bits are the unsigned exponent of base 256.
    // This exponent can be thought of as "number of bytes of N".
    // The lower 23 bits are the mantissa.
    // Bit number 24 (0x800000) represents the sign of N.
    // N = (-1^sign) * mantissa * 256^(exponent-3)
    //
    // Satoshi's original implementation used BN_bn2mpi() and BN_mpi2bn().
    // MPI uses the most significant bit of the first byte as sign.
    // Thus 0x1234560000 is compact (0x05123456)
    // and  0xc0de000000 is compact (0x0600c0de)
    // (0x05c0de00) would be -0x40de000000
    //
    // Bitcoin only uses this "compact" format for encoding difficulty
    // targets, which are unsigned 256bit quantities.  Thus, all the
    // complexities of the sign bit and using base 256 are probably an
    // implementation accident.
    //
    // This implementation directly uses shifts instead of going
    // through an intermediate MPI representation.
    CBigNum& SetCompact(unsigned int nCompact)
    {
        unsigned int nSize = nCompact >> 24;
        bool fNegative     =(nCompact & 0x00800000) != 0;
        unsigned int nWord = nCompact & 0x007fffff;
        if (nSize <= 3)
        {
            nWord >>= 8*(3-nSize);
            BN_set_word(bn, nWord);
        }
        else
        {
            BN_set_word(bn, nWord);
            BN_lshift(bn, bn, 8*(nSize-3));
        }
        BN_set_negative(bn, fNegative);
        return *this;
    }
 
    unsigned int GetCompact() const
    {
        unsigned int nSize = BN_num_bytes(bn);
        unsigned int nCompact = 0;
        if (nSize <= 3)
            nCompact = BN_get_word(bn) << 8*(3-nSize);
        else
        {
            CBigNum cbn;
            BN_rshift(cbn.bn, bn, 8*(nSize-3));
            nCompact = BN_get_word(bn);
        }
        // The 0x00800000 bit denotes the sign.
        // Thus, if it is already set, divide the mantissa by 256 and increase the exponent.
        if (nCompact & 0x00800000)
        {
            nCompact >>= 8;
            nSize++;
        }
        nCompact |= nSize << 24;
        nCompact |= (BN_is_negative(bn) ? 0x00800000 : 0);
        return nCompact;
    }
 
    void SetHex(const std::string& str)
    {
        // skip 0x
        const char* psz = str.c_str();
        while (isspace(*psz))
            psz++;
        bool fNegative = false;
        if (*psz == '-')
        {
            fNegative = true;
            psz++;
        }
        if (psz[0] == '0' && tolower(psz[1]) == 'x')
            psz += 2;
        while (isspace(*psz))
            psz++;
 
        // hex string to bignum
        static const signed char phexdigit[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
        *this = 0;
        while (isxdigit(*psz))
        {
            *this <<= 4;
            int n = phexdigit[(unsigned char)*psz++];
            *this += n;
        }
        if (fNegative)
            *this = 0 - *this;
    }
 
    bool SetHexBool(const std::string& str)
    {
        // skip 0x
        const char* psz = str.c_str();
        while (isspace(*psz))
            psz++;
        bool fNegative = false;
        if (*psz == '-')
        {
            fNegative = true;
            psz++;
        }
        if (psz[0] == '0' && tolower(psz[1]) == 'x')
            psz += 2;
        while (isspace(*psz))
            psz++;
 
        // hex string to bignum
        static const signed char phexdigit[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
        *this = 0;
        while (isxdigit(*psz))
        {
            *this <<= 4;
            int n = phexdigit[(unsigned char)*psz++];
            *this += n;
        }
        if (fNegative)
            *this = 0 - *this;
 
        return true;
    }
 
 
    std::string ToString(int nBase=10) const
    {
        CAutoBN_CTX pctx;
        CBigNum bnBase = nBase;
        CBigNum bn0 = 0;
    CBigNum locBn = *this;
        std::string str;
        BN_set_negative(locBn.bn, false);
        CBigNum dv;
        CBigNum rem;
        if (BN_cmp(locBn.bn, bn0.bn) == 0)
            return "0";
        while (BN_cmp(locBn.bn, bn0.bn) > 0)
        {
            if (!BN_div(dv.bn, rem.bn, locBn.bn, bnBase.bn, pctx))
                throw bignum_error("CBigNum::ToString() : BN_div failed");
            locBn = dv;
            unsigned int c = rem.getulong();
            str += "0123456789abcdef"[c];
        }
        if (BN_is_negative(bn))
            str += "-";
        reverse(str.begin(), str.end());
        return str;
    }
 
    std::string GetHex() const
    {
        return ToString(16);
    }
 
    unsigned int GetSerializeSize(int nType=0, int nVersion=PROTOCOL_VERSION) const
    {
        return ::GetSerializeSize(getvch(), nType, nVersion);
    }
 
    template<typename Stream>
    void Serialize(Stream& s, int nType=0, int nVersion=PROTOCOL_VERSION) const
    {
        ::Serialize(s, getvch(), nType, nVersion);
    }
 
    template<typename Stream>
    void Unserialize(Stream& s, int nType=0, int nVersion=PROTOCOL_VERSION)
    {
        std::vector<unsigned char> vch;
        ::Unserialize(s, vch, nType, nVersion);
        setvch(vch);
    }
 
    CBigNum pow(const int e) const {
        return this->pow(CBigNum(e));
    }
 
    CBigNum pow(const CBigNum& e) const {
        CAutoBN_CTX pctx;
        CBigNum ret;
        if (!BN_exp(ret.bn, bn, e.bn, pctx))
            throw bignum_error("CBigNum::pow : BN_exp failed");
        return ret;
    }
 
    CBigNum mul_mod(const CBigNum& b, const CBigNum& m) const {
        CAutoBN_CTX pctx;
        CBigNum ret;
        if (!BN_mod_mul(ret.bn, bn, b.bn, m.bn, pctx))
                throw bignum_error("CBigNum::mul_mod : BN_mod_mul failed");
 
        return ret;
    }
 
    CBigNum pow_mod(const CBigNum& e, const CBigNum& m) const {
        CAutoBN_CTX pctx;
        CBigNum ret;
        if( e < 0){
            // g^-x = (g^-1)^x
            CBigNum inv = this->inverse(m);
            CBigNum posE = e * -1;
            if (!BN_mod_exp(ret.bn, inv.bn, posE.bn, m.bn, pctx))
                throw bignum_error("CBigNum::pow_mod: BN_mod_exp failed on negative exponent");
        }else
            if (!BN_mod_exp(ret.bn, bn, e.bn, m.bn, pctx))
                throw bignum_error("CBigNum::pow_mod : BN_mod_exp failed");
 
        return ret;
    }
 
    CBigNum inverse(const CBigNum& m) const {
        CAutoBN_CTX pctx;
        CBigNum ret;
        if (!BN_mod_inverse(ret.bn, bn, m.bn, pctx))
            throw bignum_error("CBigNum::inverse*= :BN_mod_inverse");
        return ret;
    }
 
    static CBigNum generatePrime(const unsigned int numBits, bool safe = false) {
        CBigNum ret;
        if(!BN_generate_prime_ex(ret.bn, numBits, (safe == true), NULL, NULL, NULL))
            throw bignum_error("CBigNum::generatePrime*= :BN_generate_prime_ex");
        return ret;
    }
 
    CBigNum gcd( const CBigNum& b) const{
        CAutoBN_CTX pctx;
        CBigNum ret;
        if (!BN_gcd(ret.bn, bn, b.bn, pctx))
            throw bignum_error("CBigNum::gcd*= :BN_gcd");
        return ret;
    }
 
    bool isPrime(const int checks=BN_prime_checks) const {
        CAutoBN_CTX pctx;
        int ret = BN_is_prime_ex(bn, checks, pctx, NULL);
        if(ret < 0){
            throw bignum_error("CBigNum::isPrime :BN_is_prime");
        }
        return ret;
    }
 
    bool isOne() const {
        return BN_is_one(bn);
    }
 
 
 
    bool operator!() const
    {
        return BN_is_zero(bn);
    }
 
    CBigNum& operator+=(const CBigNum& b)
    {
        if (!BN_add(bn, bn, b.bn))
            throw bignum_error("CBigNum::operator+= : BN_add failed");
        return *this;
    }
 
    CBigNum& operator-=(const CBigNum& b)
    {
        if (!BN_sub(bn, bn, b.bn))
        throw bignum_error("CBigNum::operator-= : BN_sub failed");
        return *this;
    }
 
    CBigNum& operator*=(const CBigNum& b)
    {
        CAutoBN_CTX pctx;
        if (!BN_mul(bn, bn, b.bn, pctx))
            throw bignum_error("CBigNum::operator*= : BN_mul failed");
        return *this;
    }
 
    CBigNum& operator/=(const CBigNum& b)
    {
    CAutoBN_CTX pctx;
        if (!BN_div(bn, NULL, bn, b.bn, pctx))
        throw bignum_error("CBigNum::operator/= : BN_div failed");
        return *this;
    }
 
    CBigNum& operator%=(const CBigNum& b)
    {
    CAutoBN_CTX pctx;
        if (!BN_mod(bn, b.bn, bn, pctx))
        throw bignum_error("CBigNum::operator%= : BN_mod failed");
        return *this;
    }
 
    CBigNum& operator<<=(unsigned int shift)
    {
        if (!BN_lshift(bn, bn, shift))
            throw bignum_error("CBigNum:operator<<= : BN_lshift failed");
        return *this;
    }
 
    CBigNum& operator>>=(unsigned int shift)
    {
        // Note: BN_rshift segfaults on 64-bit if 2^shift is greater than the number
        //   if built on ubuntu 9.04 or 9.10, probably depends on version of OpenSSL
        CBigNum a = 1;
        a <<= shift;
        if (BN_cmp(a.bn, bn) > 0)
        {
            bn = 0;
            return *this;
        }
 
        if (!BN_rshift(bn, bn, shift))
            throw bignum_error("CBigNum:operator>>= : BN_rshift failed");
        return *this;
    }
 
 
    CBigNum& operator++()
    {
        // prefix operator
        if (!BN_add(bn, bn, BN_value_one()))
            throw bignum_error("CBigNum::operator++ : BN_add failed");
        return *this;
    }
 
    const CBigNum operator++(int)
    {
        // postfix operator
        const CBigNum ret = *this;
        ++(*this);
        return ret;
    }
 
    CBigNum& operator--()
    {
        // prefix operator
        CBigNum r;
        if (!BN_sub(r.bn, bn, BN_value_one()))
            throw bignum_error("CBigNum::operator-- : BN_sub failed");
        bn = r.bn;
        return *this;
    }
 
    const CBigNum operator--(int)
    {
        // postfix operator
        const CBigNum ret = *this;
        --(*this);
        return ret;
    }
 
    friend inline const CBigNum operator+(const CBigNum& a, const CBigNum& b);
    friend inline const CBigNum operator-(const CBigNum& a, const CBigNum& b);
    friend inline const CBigNum operator/(const CBigNum& a, const CBigNum& b);
    friend inline const CBigNum operator%(const CBigNum& a, const CBigNum& b);
    friend inline const CBigNum operator*(const CBigNum& a, const CBigNum& b);
    friend inline const CBigNum operator<<(const CBigNum& a, unsigned int shift);
    friend inline const CBigNum operator-(const CBigNum& a);
    friend inline bool operator==(const CBigNum& a, const CBigNum& b);
    friend inline bool operator!=(const CBigNum& a, const CBigNum& b);
    friend inline bool operator<=(const CBigNum& a, const CBigNum& b);
    friend inline bool operator>=(const CBigNum& a, const CBigNum& b);
    friend inline bool operator<(const CBigNum& a, const CBigNum& b);
    friend inline bool operator>(const CBigNum& a, const CBigNum& b);
};
 
 
 
inline const CBigNum operator+(const CBigNum& a, const CBigNum& b)
{
    CBigNum r;
    if (!BN_add(r.bn, a.bn, b.bn))
        throw bignum_error("CBigNum::operator+ : BN_add failed");
    return r;
}
 
inline const CBigNum operator-(const CBigNum& a, const CBigNum& b)
{
    CBigNum r;
    if (!BN_sub(r.bn, a.bn, b.bn))
        throw bignum_error("CBigNum::operator- : BN_sub failed");
    return r;
}
 
inline const CBigNum operator-(const CBigNum& a)
{
    CBigNum r(a);
    BN_set_negative(r.bn, !BN_is_negative(r.bn));
    return r;
}
 
inline const CBigNum operator*(const CBigNum& a, const CBigNum& b)
{
    CAutoBN_CTX pctx;
    CBigNum r;
    if (!BN_mul(r.bn, a.bn, b.bn, pctx))
        throw bignum_error("CBigNum::operator* : BN_mul failed");
    return r;
}
 
inline const CBigNum operator/(const CBigNum& a, const CBigNum& b)
{
    CAutoBN_CTX pctx;
    CBigNum r;
    if (!BN_div(r.bn, NULL, a.bn, b.bn, pctx))
        throw bignum_error("CBigNum::operator/ : BN_div failed");
    return r;
}
 
inline const CBigNum operator%(const CBigNum& a, const CBigNum& b)
{
    CAutoBN_CTX pctx;
    CBigNum r;
    if (!BN_nnmod(r.bn, a.bn, b.bn, pctx))
        throw bignum_error("CBigNum::operator% : BN_div failed");
    return r;
}
 
inline const CBigNum operator<<(const CBigNum& a, unsigned int shift)
{
    CBigNum r;
    if (!BN_lshift(r.bn, a.bn, shift))
        throw bignum_error("CBigNum:operator<< : BN_lshift failed");
    return r;
}
 
inline const CBigNum operator>>(const CBigNum& a, unsigned int shift)
{
    CBigNum r = a;
    r >>= shift;
    return r;
}
 
inline bool operator==(const CBigNum& a, const CBigNum& b) { return (BN_cmp(a.bn, b.bn) == 0); }
inline bool operator!=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(a.bn, b.bn) != 0); }
inline bool operator<=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(a.bn, b.bn) <= 0); }
inline bool operator>=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(a.bn, b.bn) >= 0); }
inline bool operator<(const CBigNum& a, const CBigNum& b)  { return (BN_cmp(a.bn, b.bn) < 0); }
inline bool operator>(const CBigNum& a, const CBigNum& b)  { return (BN_cmp(a.bn, b.bn) > 0); }
inline std::ostream& operator<<(std::ostream &strm, const CBigNum &b) { return strm << b.ToString(10); }
 
typedef CBigNum Bignum;
 
#endif