/// <summary> /// Generates a new, random BigInteger of the specified length. /// </summary> /// <param name="bits">The number of bits for the new number.</param> /// <param name="rng">A random number generator to use to obtain the bits.</param> /// <returns>A random number of the specified length.</returns> public static BigInteger GenerateRandom(int bits, RandomNumberGenerator rng) { int dwords = bits >> 5; int remBits = bits & 0x1F; if (remBits != 0) dwords++; var ret = new BigInteger(Sign.Positive, (uint)dwords + 1); var random = new byte[dwords << 2]; rng.GetBytes(random); Buffer.BlockCopy(random, 0, ret.data, 0, dwords << 2); if (remBits != 0) { var mask = (uint)(0x01 << (remBits - 1)); ret.data[dwords - 1] |= mask; mask = 0xFFFFFFFF >> (32 - remBits); ret.data[dwords - 1] &= mask; } else ret.data[dwords - 1] |= 0x80000000; ret.Normalize(); return ret; }
public static BigInteger MultiplyByDword(BigInteger n, uint f) { var ret = new BigInteger(Sign.Positive, n.length + 1); uint i = 0; ulong c = 0; do { c += n.data[i] * (ulong)f; ret.data[i] = (uint)c; c >>= 32; } while (++i < n.length); ret.data[i] = (uint)c; ret.Normalize(); return ret; }
public static BigInteger operator *(BigInteger bi1, BigInteger bi2) { if (bi1 == 0 || bi2 == 0) return 0; // // Validate pointers // if (bi1.data.Length < bi1.length) throw new IndexOutOfRangeException("bi1 out of range"); if (bi2.data.Length < bi2.length) throw new IndexOutOfRangeException("bi2 out of range"); var ret = new BigInteger(Sign.Positive, bi1.length + bi2.length); Kernel.Multiply(bi1.data, 0, bi1.length, bi2.data, 0, bi2.length, ret.data, 0); ret.Normalize(); return ret; }
public static BigInteger LeftShift(BigInteger bi, int n) { if (n == 0) return new BigInteger(bi, bi.length + 1); int w = n >> 5; n &= ((1 << 5) - 1); var ret = new BigInteger(Sign.Positive, bi.length + 1 + (uint)w); uint i = 0, l = bi.length; if (n != 0) { uint x, carry = 0; while (i < l) { x = bi.data[i]; ret.data[i + w] = (x << n) | carry; carry = x >> (32 - n); i++; } ret.data[i + w] = carry; } else { while (i < l) { ret.data[i + w] = bi.data[i]; i++; } } ret.Normalize(); return ret; }
public static BigInteger RightShift(BigInteger bi, int n) { if (n == 0) return new BigInteger(bi); int w = n >> 5; int s = n & ((1 << 5) - 1); var ret = new BigInteger(Sign.Positive, bi.length - (uint)w + 1); uint l = (uint)ret.data.Length - 1; if (s != 0) { uint x, carry = 0; while (l-- > 0) { x = bi.data[l + w]; ret.data[l] = (x >> n) | carry; carry = x << (32 - n); } } else { while (l-- > 0) ret.data[l] = bi.data[l + w]; } ret.Normalize(); return ret; }
public static BigInteger[] DwordDivMod(BigInteger n, uint d) { var ret = new BigInteger(Sign.Positive, n.length); ulong r = 0; uint i = n.length; while (i-- > 0) { r <<= 32; r |= n.data[i]; ret.data[i] = (uint)(r / d); r %= d; } ret.Normalize(); BigInteger rem = (uint)r; return new[] { ret, rem }; }
public static BigInteger[] multiByteDivide(BigInteger bi1, BigInteger bi2) { if (Compare(bi1, bi2) == Sign.Negative) return new BigInteger[2] { 0, new BigInteger(bi1) }; bi1.Normalize(); bi2.Normalize(); if (bi2.length == 1) return DwordDivMod(bi1, bi2.data[0]); uint remainderLen = bi1.length + 1; int divisorLen = (int)bi2.length + 1; uint mask = 0x80000000; uint val = bi2.data[bi2.length - 1]; int shift = 0; int resultPos = (int)bi1.length - (int)bi2.length; while (mask != 0 && (val & mask) == 0) { shift++; mask >>= 1; } var quot = new BigInteger(Sign.Positive, bi1.length - bi2.length + 1); BigInteger rem = (bi1 << shift); uint[] remainder = rem.data; bi2 = bi2 << shift; var j = (int)(remainderLen - bi2.length); int pos = (int)remainderLen - 1; uint firstDivisorByte = bi2.data[bi2.length - 1]; ulong secondDivisorByte = bi2.data[bi2.length - 2]; while (j > 0) { ulong dividend = ((ulong)remainder[pos] << 32) + remainder[pos - 1]; ulong q_hat = dividend / firstDivisorByte; ulong r_hat = dividend % firstDivisorByte; do { if (q_hat == 0x100000000 || (q_hat * secondDivisorByte) > ((r_hat << 32) + remainder[pos - 2])) { q_hat--; r_hat += firstDivisorByte; if (r_hat < 0x100000000) continue; } break; } while (true); // // At this point, q_hat is either exact, or one too large // (more likely to be exact) so, we attempt to multiply the // divisor by q_hat, if we get a borrow, we just subtract // one from q_hat and add the divisor back. // uint t; uint dPos = 0; int nPos = pos - divisorLen + 1; ulong mc = 0; var uint_q_hat = (uint)q_hat; do { mc += bi2.data[dPos] * (ulong)uint_q_hat; t = remainder[nPos]; remainder[nPos] -= (uint)mc; mc >>= 32; if (remainder[nPos] > t) mc++; dPos++; nPos++; } while (dPos < divisorLen); nPos = pos - divisorLen + 1; dPos = 0; // Overestimate if (mc != 0) { uint_q_hat--; ulong sum = 0; do { sum = remainder[nPos] + ((ulong)bi2.data[dPos]) + sum; remainder[nPos] = (uint)sum; sum >>= 32; dPos++; nPos++; } while (dPos < divisorLen); } quot.data[resultPos--] = uint_q_hat; pos--; j--; } quot.Normalize(); rem.Normalize(); var ret = new BigInteger[2] { quot, rem }; if (shift != 0) ret[1] >>= shift; return ret; }
public static void PlusEq(BigInteger bi1, BigInteger bi2) { uint[] x, y; uint yMax, xMax, i = 0; bool flag = false; // x should be bigger if (bi1.length < bi2.length) { flag = true; x = bi2.data; xMax = bi2.length; y = bi1.data; yMax = bi1.length; } else { x = bi1.data; xMax = bi1.length; y = bi2.data; yMax = bi2.length; } uint[] r = bi1.data; ulong sum = 0; // Add common parts of both numbers do { sum += x[i] + ((ulong)y[i]); r[i] = (uint)sum; sum >>= 32; } while (++i < yMax); // Copy remainder of longer number while carry propagation is required bool carry = (sum != 0); if (carry) { if (i < xMax) { do carry = ((r[i] = x[i] + 1) == 0); while (++i < xMax && carry); } if (carry) { r[i] = 1; bi1.length = ++i; return; } } // Copy the rest if (flag && i < xMax - 1) { do r[i] = x[i]; while (++i < xMax); } bi1.length = xMax + 1; bi1.Normalize(); }
/// <summary> /// Performs n / d and n % d in one operation. /// </summary> /// <param name="n">A BigInteger, upon exit this will hold n / d</param> /// <param name="d">The divisor</param> /// <returns>n % d</returns> public static uint SingleByteDivideInPlace(BigInteger n, uint d) { ulong r = 0; uint i = n.length; while (i-- > 0) { r <<= 32; r |= n.data[i]; n.data[i] = (uint)(r / d); r %= d; } n.Normalize(); return (uint)r; }
public static BigInteger Subtract(BigInteger big, BigInteger small) { var result = new BigInteger(Sign.Positive, big.length); uint[] r = result.data, b = big.data, s = small.data; uint i = 0, c = 0; do { uint x = s[i]; if (((x += c) < c) | ((r[i] = b[i] - x) > ~x)) c = 1; else c = 0; } while (++i < small.length); if (i == big.length) goto fixup; if (c == 1) { do r[i] = b[i] - 1; while (b[i++] == 0 && i < big.length); if (i == big.length) goto fixup; } do r[i] = b[i]; while (++i < big.length); fixup: result.Normalize(); return result; }
/// <summary> /// Adds two numbers with the same sign. /// </summary> /// <param name="bi1">A BigInteger</param> /// <param name="bi2">A BigInteger</param> /// <returns>bi1 + bi2</returns> public static BigInteger AddSameSign(BigInteger bi1, BigInteger bi2) { uint[] x, y; uint yMax, xMax, i = 0; // x should be bigger if (bi1.length < bi2.length) { x = bi2.data; xMax = bi2.length; y = bi1.data; yMax = bi1.length; } else { x = bi1.data; xMax = bi1.length; y = bi2.data; yMax = bi2.length; } var result = new BigInteger(Sign.Positive, xMax + 1); uint[] r = result.data; ulong sum = 0; // Add common parts of both numbers do { sum = x[i] + ((ulong)y[i]) + sum; r[i] = (uint)sum; sum >>= 32; } while (++i < yMax); // Copy remainder of longer number while carry propagation is required bool carry = (sum != 0); if (carry) { if (i < xMax) { do carry = ((r[i] = x[i] + 1) == 0); while (++i < xMax && carry); } if (carry) { r[i] = 1; result.length = ++i; return result; } } // Copy the rest if (i < xMax) { do r[i] = x[i]; while (++i < xMax); } result.Normalize(); return result; }
/* known to be buggy in some cases */ #if false private unsafe BigInteger EvenModTwoPow (BigInteger exp) { exp.Normalize (); uint [] wkspace = new uint [mod.length << 1 + 1]; BigInteger resultNum = new BigInteger (2, mod.length << 1 +1); uint value = exp.data [exp.length - 1]; uint mask = 0x80000000; // Find the first bit of the exponent while ((value & mask) == 0) mask >>= 1; // // We know that the first itr will make the val 2, // so eat one bit of the exponent // mask >>= 1; uint wPos = exp.length - 1; do { value = exp.data [wPos]; do { Kernel.SquarePositive (resultNum, ref wkspace); if (resultNum.length >= mod.length) BarrettReduction (resultNum); if ((value & mask) != 0) { // // resultNum = (resultNum * 2) % mod // fixed (uint* u = resultNum.data) { // // Double // uint* uu = u; uint* uuE = u + resultNum.length; uint x, carry = 0; while (uu < uuE) { x = *uu; *uu = (x << 1) | carry; carry = x >> (32 - 1); uu++; } // subtraction inlined because we know it is square if (carry != 0 || resultNum >= mod) { uu = u; uint c = 0; uint [] s = mod.data; uint i = 0; do { uint a = s [i]; if (((a += c) < c) | ((* (uu++) -= a) > ~a)) c = 1; else c = 0; i++; } while (uu < uuE); } } } } while ((mask >>= 1) > 0); mask = 0x80000000; } while (wPos-- > 0); return resultNum; }
private unsafe BigInteger EvenPow (uint b, BigInteger exp) { exp.Normalize (); uint [] wkspace = new uint [mod.length << 1 + 1]; BigInteger resultNum = new BigInteger ((BigInteger)b, mod.length << 1 + 1); uint pos = (uint)exp.BitCount () - 2; // // We know that the first itr will make the val b // do { // // r = r ^ 2 % m // Kernel.SquarePositive (resultNum, ref wkspace); if (!(resultNum.length < mod.length)) BarrettReduction (resultNum); if (exp.TestBit (pos)) { // // r = r * b % m // // TODO: Is Unsafe really speeding things up? fixed (uint* u = resultNum.data) { uint i = 0; ulong mc = 0; do { mc += (ulong)u [i] * (ulong)b; u [i] = (uint)mc; mc >>= 32; } while (++i < resultNum.length); if (resultNum.length < mod.length) { if (mc != 0) { u [i] = (uint)mc; resultNum.length++; while (resultNum >= mod) Kernel.MinusEq (resultNum, mod); } } else if (mc != 0) { // // First, we estimate the quotient by dividing // the first part of each of the numbers. Then // we correct this, if necessary, with a subtraction. // uint cc = (uint)mc; // We would rather have this estimate overshoot, // so we add one to the divisor uint divEstimate = (uint) ((((ulong)cc << 32) | (ulong) u [i -1]) / (mod.data [mod.length-1] + 1)); uint t; i = 0; mc = 0; do { mc += (ulong)mod.data [i] * (ulong)divEstimate; t = u [i]; u [i] -= (uint)mc; mc >>= 32; if (u [i] > t) mc++; i++; } while (i < resultNum.length); cc -= (uint)mc; if (cc != 0) { uint sc = 0, j = 0; uint [] s = mod.data; do { uint a = s [j]; if (((a += sc) < sc) | ((u [j] -= a) > ~a)) sc = 1; else sc = 0; j++; } while (j < resultNum.length); cc -= sc; } while (resultNum >= mod) Kernel.MinusEq (resultNum, mod); } else { while (resultNum >= mod) Kernel.MinusEq (resultNum, mod); } } } } while (pos-- > 0); return resultNum; }
public void BarrettReduction(BigInteger x) { BigInteger n = mod; uint k = n.length, kPlusOne = k + 1, kMinusOne = k - 1; // x < mod, so nothing to do. if (x.length < k) return; BigInteger q3; // // Validate pointers // if (x.data.Length < x.length) throw new IndexOutOfRangeException("x out of range"); // q1 = x / b^ (k-1) // q2 = q1 * constant // q3 = q2 / b^ (k+1), Needs to be accessed with an offset of kPlusOne // TODO: We should the method in HAC p 604 to do this (14.45) q3 = new BigInteger(Sign.Positive, x.length - kMinusOne + constant.length); Kernel.Multiply(x.data, kMinusOne, x.length - kMinusOne, constant.data, 0, constant.length, q3.data, 0); // r1 = x mod b^ (k+1) // i.e. keep the lowest (k+1) words uint lengthToCopy = (x.length > kPlusOne) ? kPlusOne : x.length; x.length = lengthToCopy; x.Normalize(); // r2 = (q3 * n) mod b^ (k+1) // partial multiplication of q3 and n var r2 = new BigInteger(Sign.Positive, kPlusOne); Kernel.MultiplyMod2p32pmod(q3.data, (int)kPlusOne, (int)q3.length - (int)kPlusOne, n.data, 0, (int)n.length, r2.data, 0, (int)kPlusOne); r2.Normalize(); if (r2 <= x) { Kernel.MinusEq(x, r2); } else { var val = new BigInteger(Sign.Positive, kPlusOne + 1); val.data[kPlusOne] = 0x00000001; Kernel.MinusEq(val, r2); Kernel.PlusEq(x, val); } while (x >= n) Kernel.MinusEq(x, n); }