1 // Copyright (c) 2009-2010 Satoshi Nakamoto
2 // Copyright (c) 2009-2012 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 #ifndef BITCOIN_BIGNUM_H
6 #define BITCOIN_BIGNUM_H
10 #include <openssl/bn.h>
13 /** Errors thrown by the bignum class */
14 class bignum_error : public std::runtime_error
17 explicit bignum_error(const std::string& str) : std::runtime_error(str) {}
21 /** RAII encapsulated BN_CTX (OpenSSL bignum context) */
26 BN_CTX* operator=(BN_CTX* pnew) { return pctx = pnew; }
33 throw bignum_error("CAutoBN_CTX : BN_CTX_new() returned NULL");
42 operator BN_CTX*() { return pctx; }
43 BN_CTX& operator*() { return *pctx; }
44 BN_CTX** operator&() { return &pctx; }
45 bool operator!() { return (pctx == NULL); }
49 /** C++ wrapper for BIGNUM (OpenSSL bignum) */
50 class CBigNum : public BIGNUM
58 CBigNum(const CBigNum& b)
61 if (!BN_copy(this, &b))
64 throw bignum_error("CBigNum::CBigNum(const CBigNum&) : BN_copy failed");
68 CBigNum& operator=(const CBigNum& b)
70 if (!BN_copy(this, &b))
71 throw bignum_error("CBigNum::operator= : BN_copy failed");
80 CBigNum(int8_t n) { BN_init(this); if (n >= 0) setuint32(n); else setint64(n); }
81 CBigNum(int16_t n) { BN_init(this); if (n >= 0) setuint32(n); else setint64(n); }
82 CBigNum(int32_t n) { BN_init(this); if (n >= 0) setuint32(n); else setint64(n); }
83 CBigNum(int64_t n) { BN_init(this); if (n >= 0) setuint64(n); else setint64(n); }
85 CBigNum(uint8_t n) { BN_init(this); setuint32(n); }
86 CBigNum(uint16_t n) { BN_init(this); setuint32(n); }
87 CBigNum(uint32_t n) { BN_init(this); setuint32(n); }
88 CBigNum(uint64_t n) { BN_init(this); setuint64(n); }
90 explicit CBigNum(uint256 n) { BN_init(this); setuint256(n); }
91 explicit CBigNum(const std::vector<unsigned char>& vch)
97 /** Generates a cryptographically secure random number between zero and range exclusive
98 * i.e. 0 < returned number < range
99 * @param range The upper bound on the number.
102 static CBigNum randBignum(const CBigNum& range) {
104 if(!BN_rand_range(&ret, &range)){
105 throw bignum_error("CBigNum:rand element : BN_rand_range failed");
110 /** Generates a cryptographically secure random k-bit number
111 * @param k The bit length of the number.
114 static CBigNum RandKBitBigum(const uint32_t k){
116 if(!BN_rand(&ret, k, -1, 0)){
117 throw bignum_error("CBigNum:rand element : BN_rand failed");
122 /**Returns the size in bits of the underlying bignum.
127 return BN_num_bits(this);
131 void setuint32(uint32_t n)
133 if (!BN_set_word(this, n))
134 throw bignum_error("CBigNum conversion from uint32_t : BN_set_word failed");
137 uint32_t getuint32() const
139 return BN_get_word(this);
142 int32_t getint32() const
144 uint64_t n = BN_get_word(this);
145 if (!BN_is_negative(this))
146 return (n > (uint64_t)std::numeric_limits<int32_t>::max() ? std::numeric_limits<int32_t>::max() : n);
148 return (n > (uint64_t)std::numeric_limits<int32_t>::max() ? std::numeric_limits<int32_t>::min() : -(int32_t)n);
151 void setint64(int64_t sn)
153 unsigned char pch[sizeof(sn) + 6];
154 unsigned char* p = pch + 4;
160 // 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
169 bool fLeadingZeroes = true;
170 for (int i = 0; i < 8; i++)
172 unsigned char c = (n >> 56) & 0xff;
179 *p++ = (fNegative ? 0x80 : 0);
182 fLeadingZeroes = false;
186 uint32_t nSize = p - (pch + 4);
187 pch[0] = (nSize >> 24) & 0xff;
188 pch[1] = (nSize >> 16) & 0xff;
189 pch[2] = (nSize >> 8) & 0xff;
190 pch[3] = (nSize) & 0xff;
191 BN_mpi2bn(pch, p - pch, this);
196 unsigned int nSize = BN_bn2mpi(this, NULL);
199 std::vector<unsigned char> vch(nSize);
200 BN_bn2mpi(this, &vch[0]);
204 for (unsigned int i = 0, j = vch.size()-1; i < sizeof(n) && j >= 4; i++, j--)
205 ((unsigned char*)&n)[i] = vch[j];
209 void setuint64(uint64_t n)
211 unsigned char pch[sizeof(n) + 6];
212 unsigned char* p = pch + 4;
213 bool fLeadingZeroes = true;
214 for (int i = 0; i < 8; i++)
216 unsigned char c = (n >> 56) & 0xff;
224 fLeadingZeroes = false;
228 uint32_t nSize = p - (pch + 4);
229 pch[0] = (nSize >> 24) & 0xff;
230 pch[1] = (nSize >> 16) & 0xff;
231 pch[2] = (nSize >> 8) & 0xff;
232 pch[3] = (nSize) & 0xff;
233 BN_mpi2bn(pch, p - pch, this);
236 void setuint160(uint160 n)
238 unsigned char pch[sizeof(n) + 6];
239 unsigned char* p = pch + 4;
240 bool fLeadingZeroes = true;
241 unsigned char* pbegin = (unsigned char*)&n;
242 unsigned char* psrc = pbegin + sizeof(n);
243 while (psrc != pbegin)
245 unsigned char c = *(--psrc);
252 fLeadingZeroes = false;
256 uint32_t nSize = p - (pch + 4);
257 pch[0] = (nSize >> 24) & 0xff;
258 pch[1] = (nSize >> 16) & 0xff;
259 pch[2] = (nSize >> 8) & 0xff;
260 pch[3] = (nSize >> 0) & 0xff;
261 BN_mpi2bn(pch, p - pch, this);
264 uint160 getuint160() const
266 unsigned int nSize = BN_bn2mpi(this, NULL);
269 std::vector<unsigned char> vch(nSize);
270 BN_bn2mpi(this, &vch[0]);
274 for (unsigned int i = 0, j = vch.size()-1; i < sizeof(n) && j >= 4; i++, j--)
275 ((unsigned char*)&n)[i] = vch[j];
279 void setuint256(uint256 n)
281 unsigned char pch[sizeof(n) + 6];
282 unsigned char* p = pch + 4;
283 bool fLeadingZeroes = true;
284 unsigned char* pbegin = (unsigned char*)&n;
285 unsigned char* psrc = pbegin + sizeof(n);
286 while (psrc != pbegin)
288 unsigned char c = *(--psrc);
295 fLeadingZeroes = false;
299 uint32_t nSize = p - (pch + 4);
300 pch[0] = (nSize >> 24) & 0xff;
301 pch[1] = (nSize >> 16) & 0xff;
302 pch[2] = (nSize >> 8) & 0xff;
303 pch[3] = (nSize >> 0) & 0xff;
304 BN_mpi2bn(pch, p - pch, this);
307 uint256 getuint256() const
309 unsigned int nSize = BN_bn2mpi(this, NULL);
312 std::vector<unsigned char> vch(nSize);
313 BN_bn2mpi(this, &vch[0]);
317 for (unsigned int i = 0, j = vch.size()-1; i < sizeof(n) && j >= 4; i++, j--)
318 ((unsigned char*)&n)[i] = vch[j];
322 void setBytes(const std::vector<unsigned char>& vchBytes)
324 BN_bin2bn(&vchBytes[0], vchBytes.size(), this);
327 std::vector<unsigned char> getBytes() const
329 int nBytes = BN_num_bytes(this);
331 std::vector<unsigned char> vchBytes(nBytes);
333 int n = BN_bn2bin(this, &vchBytes[0]);
335 throw bignum_error("CBigNum::getBytes : BN_bn2bin failed");
341 void setvch(const std::vector<unsigned char>& vch)
343 std::vector<unsigned char> vch2(vch.size() + 4);
344 uint32_t nSize = vch.size();
345 // BIGNUM's byte stream format expects 4 bytes of
346 // big endian size data info at the front
347 vch2[0] = (nSize >> 24) & 0xff;
348 vch2[1] = (nSize >> 16) & 0xff;
349 vch2[2] = (nSize >> 8) & 0xff;
350 vch2[3] = (nSize >> 0) & 0xff;
351 // swap data to big endian
352 reverse_copy(vch.begin(), vch.end(), vch2.begin() + 4);
353 BN_mpi2bn(&vch2[0], vch2.size(), this);
356 std::vector<unsigned char> getvch() const
358 unsigned int nSize = BN_bn2mpi(this, NULL);
360 return std::vector<unsigned char>();
361 std::vector<unsigned char> vch(nSize);
362 BN_bn2mpi(this, &vch[0]);
363 vch.erase(vch.begin(), vch.begin() + 4);
364 reverse(vch.begin(), vch.end());
368 CBigNum& SetCompact(uint32_t nCompact)
370 uint32_t nSize = nCompact >> 24;
371 std::vector<unsigned char> vch(4 + nSize);
373 if (nSize >= 1) vch[4] = (nCompact >> 16) & 0xff;
374 if (nSize >= 2) vch[5] = (nCompact >> 8) & 0xff;
375 if (nSize >= 3) vch[6] = (nCompact >> 0) & 0xff;
376 BN_mpi2bn(&vch[0], vch.size(), this);
380 uint32_t GetCompact() const
382 uint32_t nSize = BN_bn2mpi(this, NULL);
383 std::vector<unsigned char> vch(nSize);
385 BN_bn2mpi(this, &vch[0]);
386 uint32_t nCompact = nSize << 24;
387 if (nSize >= 1) nCompact |= (vch[4] << 16);
388 if (nSize >= 2) nCompact |= (vch[5] << 8);
389 if (nSize >= 3) nCompact |= (vch[6] << 0);
393 void SetHex(const std::string& str)
396 const char* psz = str.c_str();
397 while (isspace(*psz))
399 bool fNegative = false;
405 if (psz[0] == '0' && tolower(psz[1]) == 'x')
407 while (isspace(*psz))
410 // hex string to bignum
411 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 };
413 while (isxdigit(*psz))
416 int n = phexdigit[(unsigned char)*psz++];
423 std::string ToString(int nBase=10) const
426 CBigNum bnBase = nBase;
430 BN_set_negative(&bn, false);
433 if (BN_cmp(&bn, &bn0) == 0)
435 while (BN_cmp(&bn, &bn0) > 0)
437 if (!BN_div(&dv, &rem, &bn, &bnBase, pctx))
438 throw bignum_error("CBigNum::ToString() : BN_div failed");
440 unsigned int c = rem.getuint32();
441 str += "0123456789abcdef"[c];
443 if (BN_is_negative(this))
445 reverse(str.begin(), str.end());
449 std::string GetHex() const
454 unsigned int GetSerializeSize(int nType=0, int nVersion=PROTOCOL_VERSION) const
456 return ::GetSerializeSize(getvch(), nType, nVersion);
459 template<typename Stream>
460 void Serialize(Stream& s, int nType=0, int nVersion=PROTOCOL_VERSION) const
462 ::Serialize(s, getvch(), nType, nVersion);
465 template<typename Stream>
466 void Unserialize(Stream& s, int nType=0, int nVersion=PROTOCOL_VERSION)
468 std::vector<unsigned char> vch;
469 ::Unserialize(s, vch, nType, nVersion);
474 * exponentiation with an int. this^e
475 * @param e the exponent as an int
478 CBigNum pow(const int e) const {
479 return this->pow(CBigNum(e));
483 * exponentiation this^e
484 * @param e the exponent
487 CBigNum pow(const CBigNum& e) const {
490 if (!BN_exp(&ret, this, &e, pctx))
491 throw bignum_error("CBigNum::pow : BN_exp failed");
496 * modular multiplication: (this * b) mod m
500 CBigNum mul_mod(const CBigNum& b, const CBigNum& m) const {
503 if (!BN_mod_mul(&ret, this, &b, &m, pctx))
504 throw bignum_error("CBigNum::mul_mod : BN_mod_mul failed");
510 * modular exponentiation: this^e mod n
514 CBigNum pow_mod(const CBigNum& e, const CBigNum& m) const {
519 CBigNum inv = this->inverse(m);
520 CBigNum posE = e * -1;
521 if (!BN_mod_exp(&ret, &inv, &posE, &m, pctx))
522 throw bignum_error("CBigNum::pow_mod: BN_mod_exp failed on negative exponent");
524 if (!BN_mod_exp(&ret, this, &e, &m, pctx))
525 throw bignum_error("CBigNum::pow_mod : BN_mod_exp failed");
531 * Calculates the inverse of this element mod m.
532 * i.e. i such this*i = 1 mod m
534 * @return the inverse
536 CBigNum inverse(const CBigNum& m) const {
539 if (!BN_mod_inverse(&ret, this, &m, pctx))
540 throw bignum_error("CBigNum::inverse*= :BN_mod_inverse");
545 * Generates a random (safe) prime of numBits bits
546 * @param numBits the number of bits
547 * @param safe true for a safe prime
550 static CBigNum generatePrime(const unsigned int numBits, bool safe = false) {
552 if(!BN_generate_prime_ex(&ret, numBits, (safe == true), NULL, NULL, NULL))
553 throw bignum_error("CBigNum::generatePrime*= :BN_generate_prime_ex");
558 * Calculates the greatest common divisor (GCD) of two numbers.
559 * @param m the second element
562 CBigNum gcd( const CBigNum& b) const{
565 if (!BN_gcd(&ret, this, &b, pctx))
566 throw bignum_error("CBigNum::gcd*= :BN_gcd");
571 * Miller-Rabin primality test on this element
572 * @param checks: optional, the number of Miller-Rabin tests to run
573 * default causes error rate of 2^-80.
574 * @return true if prime
576 bool isPrime(const int checks=BN_prime_checks) const {
578 int ret = BN_is_prime(this, checks, NULL, pctx, NULL);
580 throw bignum_error("CBigNum::isPrime :BN_is_prime");
586 return BN_is_one(this);
590 bool operator!() const
592 return BN_is_zero(this);
595 CBigNum& operator+=(const CBigNum& b)
597 if (!BN_add(this, this, &b))
598 throw bignum_error("CBigNum::operator+= : BN_add failed");
602 CBigNum& operator-=(const CBigNum& b)
608 CBigNum& operator*=(const CBigNum& b)
611 if (!BN_mul(this, this, &b, pctx))
612 throw bignum_error("CBigNum::operator*= : BN_mul failed");
616 CBigNum& operator/=(const CBigNum& b)
622 CBigNum& operator%=(const CBigNum& b)
628 CBigNum& operator<<=(unsigned int shift)
630 if (!BN_lshift(this, this, shift))
631 throw bignum_error("CBigNum:operator<<= : BN_lshift failed");
635 CBigNum& operator>>=(unsigned int shift)
637 // Note: BN_rshift segfaults on 64-bit if 2^shift is greater than the number
638 // if built on ubuntu 9.04 or 9.10, probably depends on version of OpenSSL
641 if (BN_cmp(&a, this) > 0)
647 if (!BN_rshift(this, this, shift))
648 throw bignum_error("CBigNum:operator>>= : BN_rshift failed");
653 CBigNum& operator++()
656 if (!BN_add(this, this, BN_value_one()))
657 throw bignum_error("CBigNum::operator++ : BN_add failed");
661 const CBigNum operator++(int)
664 const CBigNum ret = *this;
669 CBigNum& operator--()
673 if (!BN_sub(&r, this, BN_value_one()))
674 throw bignum_error("CBigNum::operator-- : BN_sub failed");
679 const CBigNum operator--(int)
682 const CBigNum ret = *this;
688 friend inline const CBigNum operator-(const CBigNum& a, const CBigNum& b);
689 friend inline const CBigNum operator/(const CBigNum& a, const CBigNum& b);
690 friend inline const CBigNum operator%(const CBigNum& a, const CBigNum& b);
691 friend inline const CBigNum operator*(const CBigNum& a, const CBigNum& b);
692 friend inline bool operator<(const CBigNum& a, const CBigNum& b);
697 inline const CBigNum operator+(const CBigNum& a, const CBigNum& b)
700 if (!BN_add(&r, &a, &b))
701 throw bignum_error("CBigNum::operator+ : BN_add failed");
705 inline const CBigNum operator-(const CBigNum& a, const CBigNum& b)
708 if (!BN_sub(&r, &a, &b))
709 throw bignum_error("CBigNum::operator- : BN_sub failed");
713 inline const CBigNum operator-(const CBigNum& a)
716 BN_set_negative(&r, !BN_is_negative(&r));
720 inline const CBigNum operator*(const CBigNum& a, const CBigNum& b)
724 if (!BN_mul(&r, &a, &b, pctx))
725 throw bignum_error("CBigNum::operator* : BN_mul failed");
729 inline const CBigNum operator/(const CBigNum& a, const CBigNum& b)
733 if (!BN_div(&r, NULL, &a, &b, pctx))
734 throw bignum_error("CBigNum::operator/ : BN_div failed");
738 inline const CBigNum operator%(const CBigNum& a, const CBigNum& b)
742 if (!BN_nnmod(&r, &a, &b, pctx))
743 throw bignum_error("CBigNum::operator% : BN_div failed");
747 inline const CBigNum operator<<(const CBigNum& a, unsigned int shift)
750 if (!BN_lshift(&r, &a, shift))
751 throw bignum_error("CBigNum:operator<< : BN_lshift failed");
755 inline const CBigNum operator>>(const CBigNum& a, unsigned int shift)
762 inline bool operator==(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) == 0); }
763 inline bool operator!=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) != 0); }
764 inline bool operator<=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) <= 0); }
765 inline bool operator>=(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) >= 0); }
766 inline bool operator<(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) < 0); }
767 inline bool operator>(const CBigNum& a, const CBigNum& b) { return (BN_cmp(&a, &b) > 0); }
769 inline std::ostream& operator<<(std::ostream &strm, const CBigNum &b) { return strm << b.ToString(10); }
771 typedef CBigNum Bignum;