src/test/bignum.h

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2013 The Bitcoin developers
   3 // Distributed under the MIT/X11 software license, see the accompanying
   4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5
   6 #ifndef BITCOIN_BIGNUM_H
   7 #define BITCOIN_BIGNUM_H
   8
   9 #include <algorithm>
  10 #include <limits>
  11 #include <stdexcept>
  12 #include <stdint.h>
  13 #include <string>
  14 #include <vector>
  15
  16 #include <openssl/bn.h>
  17
  18 class bignum_error : public std::runtime_error
  19 {
  20 public:
  21     explicit bignum_error(const std::string& str) : std::runtime_error(str) {}
  22 };
  23
  24
  25 /** C++ wrapper for BIGNUM (OpenSSL bignum) */
  26 class CBigNum : public BIGNUM
  27 {
  28 public:
  29     CBigNum()
  30     {
  31         BN_init(this);
  32     }
  33
  34     CBigNum(const CBigNum& b)
  35     {
  36         BN_init(this);
  37         if (!BN_copy(this, &b))
  38         {
  39             BN_clear_free(this);
  40             throw bignum_error("CBigNum::CBigNum(const CBigNum&) : BN_copy failed");
  41         }
  42     }
  43
  44     CBigNum& operator=(const CBigNum& b)
  45     {
  46         if (!BN_copy(this, &b))
  47             throw bignum_error("CBigNum::operator= : BN_copy failed");
  48         return (*this);
  49     }
  50
  51     ~CBigNum()
  52     {
  53         BN_clear_free(this);
  54     }
  55
  56     CBigNum(long long n)          { BN_init(this); setint64(n); }
  57
  58     explicit CBigNum(const std::vector<unsigned char>& vch)
  59     {
  60         BN_init(this);
  61         setvch(vch);
  62     }
  63
  64     int getint() const
  65     {
  66         unsigned long n = BN_get_word(this);
  67         if (!BN_is_negative(this))
  68             return (n > (unsigned long)std::numeric_limits<int>::max() ? std::numeric_limits<int>::max() : n);
  69         else
  70             return (n > (unsigned long)std::numeric_limits<int>::max() ? std::numeric_limits<int>::min() : -(int)n);
  71     }
  72
  73     void setint64(int64_t sn)
  74     {
  75         unsigned char pch[sizeof(sn) + 6];
  76         unsigned char* p = pch + 4;
  77         bool fNegative;
  78         uint64_t n;
  79
  80         if (sn < (int64_t)0)
  81         {
  82             // Since the minimum signed integer cannot be represented as positive so long as its type is signed,
  83             // and it's not well-defined what happens if you make it unsigned before negating it,
  84             // we instead increment the negative integer by 1, convert it, then increment the (now positive) unsigned integer by 1 to compensate
  85             n = -(sn + 1);
  86             ++n;
  87             fNegative = true;
  88         } else {
  89             n = sn;
  90             fNegative = false;
  91         }
  92
  93         bool fLeadingZeroes = true;
  94         for (int i = 0; i < 8; i++)
  95         {
  96             unsigned char c = (n >> 56) & 0xff;
  97             n <<= 8;
  98             if (fLeadingZeroes)
  99             {
 100                 if (c == 0)
 101                     continue;
 102                 if (c & 0x80)
 103                     *p++ = (fNegative ? 0x80 : 0);
 104                 else if (fNegative)
 105                     c |= 0x80;
 106                 fLeadingZeroes = false;
 107             }
 108             *p++ = c;
 109         }
 110         unsigned int nSize = p - (pch + 4);
 111         pch[0] = (nSize >> 24) & 0xff;
 112         pch[1] = (nSize >> 16) & 0xff;
 113         pch[2] = (nSize >> 8) & 0xff;
 114         pch[3] = (nSize) & 0xff;
 115         BN_mpi2bn(pch, p - pch, this);
 116     }
 117
 118     void setvch(const std::vector<unsigned char>& vch)
 119     {
 120         std::vector<unsigned char> vch2(vch.size() + 4);
 121         unsigned int nSize = vch.size();
 122         // BIGNUM's byte stream format expects 4 bytes of
 123         // big endian size data info at the front
 124         vch2[0] = (nSize >> 24) & 0xff;
 125         vch2[1] = (nSize >> 16) & 0xff;
 126         vch2[2] = (nSize >> 8) & 0xff;
 127         vch2[3] = (nSize >> 0) & 0xff;
 128         // swap data to big endian
 129         reverse_copy(vch.begin(), vch.end(), vch2.begin() + 4);
 130         BN_mpi2bn(&vch2[0], vch2.size(), this);
 131     }
 132
 133     std::vector<unsigned char> getvch() const
 134     {
 135         unsigned int nSize = BN_bn2mpi(this, NULL);
 136         if (nSize <= 4)
 137             return std::vector<unsigned char>();
 138         std::vector<unsigned char> vch(nSize);
 139         BN_bn2mpi(this, &vch[0]);
 140         vch.erase(vch.begin(), vch.begin() + 4);
 141         reverse(vch.begin(), vch.end());
 142         return vch;
 143     }
 144
 145     friend inline const CBigNum operator-(const CBigNum& a, const CBigNum& b);
 146 };
 147
 148
 149
 150 inline const CBigNum operator+(const CBigNum& a, const CBigNum& b)
 151 {
 152     CBigNum r;
 153     if (!BN_add(&r, &a, &b))
 154         throw bignum_error("CBigNum::operator+ : BN_add failed");
 155     return r;
 156 }
 157
 158 inline const CBigNum operator-(const CBigNum& a, const CBigNum& b)
 159 {
 160     CBigNum r;
 161     if (!BN_sub(&r, &a, &b))
 162         throw bignum_error("CBigNum::operator- : BN_sub failed");
 163     return r;
 164 }
 165
 166 inline const CBigNum operator-(const CBigNum& a)
 167 {
 168     CBigNum r(a);
 169     BN_set_negative(&r, !BN_is_negative(&r));
 170     return r;
 171 }
 172
 173 inline bool operator==(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) == 0); }
 174 inline bool operator!=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) != 0); }
 175 inline bool operator<=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) <= 0); }
 176 inline bool operator>=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) >= 0); }
 177 inline bool operator<(const CBigNum& a, const CBigNum& b)  { return (BN_cmp(&a, &b) < 0); }
 178 inline bool operator>(const CBigNum& a, const CBigNum& b)  { return (BN_cmp(&a, &b) > 0); }
 179
 180 #endif