1 files changed, 196 insertions, 0 deletions
diff --git a/cli/vendor/github.com/decred/dcrd/dcrec/secp256k1/v4/genstatics.go b/cli/vendor/github.com/decred/dcrd/dcrec/secp256k1/v4/genstatics.go
new file mode 100644
index 0000000..fa613de
--- /dev/null
+++ b/cli/vendor/github.com/decred/dcrd/dcrec/secp256k1/v4/genstatics.go
@@ -0,0 +1,196 @@
+// Copyright (c) 2014-2015 The btcsuite developers
+// Copyright (c) 2015-2021 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+// This file is ignored during the regular build due to the following build tag.
+// This build tag is set during go generate.
+//go:build gensecp256k1
+// +build gensecp256k1
+
+package secp256k1
+
+// References:
+//   [GECC]: Guide to Elliptic Curve Cryptography (Hankerson, Menezes, Vanstone)
+
+import (
+	"encoding/binary"
+	"math/big"
+)
+
+// compressedBytePoints are dummy points used so the code which generates the
+// real values can compile.
+var compressedBytePoints = ""
+
+// SerializedBytePoints returns a serialized byte slice which contains all of
+// the possible points per 8-bit window.  This is used to when generating
+// compressedbytepoints.go.
+func SerializedBytePoints() []byte {
+	// Calculate G^(2^i) for i in 0..255.  These are used to avoid recomputing
+	// them for each digit of the 8-bit windows.
+	doublingPoints := make([]JacobianPoint, curveParams.BitSize)
+	var q JacobianPoint
+	bigAffineToJacobian(curveParams.Gx, curveParams.Gy, &q)
+	for i := 0; i < curveParams.BitSize; i++ {
+		// Q = 2*Q.
+		doublingPoints[i] = q
+		DoubleNonConst(&q, &q)
+	}
+
+	// Separate the bits into byte-sized windows.
+	curveByteSize := curveParams.BitSize / 8
+	serialized := make([]byte, curveByteSize*256*2*10*4)
+	offset := 0
+	for byteNum := 0; byteNum < curveByteSize; byteNum++ {
+		// Grab the 8 bits that make up this byte from doubling points.
+		startingBit := 8 * (curveByteSize - byteNum - 1)
+		windowPoints := doublingPoints[startingBit : startingBit+8]
+
+		// Compute all points in this window, convert them to affine, and
+		// serialize them.
+		for i := 0; i < 256; i++ {
+			var point JacobianPoint
+			for bit := 0; bit < 8; bit++ {
+				if i>>uint(bit)&1 == 1 {
+					AddNonConst(&point, &windowPoints[bit], &point)
+				}
+			}
+			point.ToAffine()
+
+			for i := 0; i < len(point.X.n); i++ {
+				binary.LittleEndian.PutUint32(serialized[offset:], point.X.n[i])
+				offset += 4
+			}
+			for i := 0; i < len(point.Y.n); i++ {
+				binary.LittleEndian.PutUint32(serialized[offset:], point.Y.n[i])
+				offset += 4
+			}
+		}
+	}
+
+	return serialized
+}
+
+// sqrt returns the square root of the provided big integer using Newton's
+// method.  It's only compiled and used during generation of pre-computed
+// values, so speed is not a huge concern.
+func sqrt(n *big.Int) *big.Int {
+	// Initial guess = 2^(log_2(n)/2)
+	guess := big.NewInt(2)
+	guess.Exp(guess, big.NewInt(int64(n.BitLen()/2)), nil)
+
+	// Now refine using Newton's method.
+	big2 := big.NewInt(2)
+	prevGuess := big.NewInt(0)
+	for {
+		prevGuess.Set(guess)
+		guess.Add(guess, new(big.Int).Div(n, guess))
+		guess.Div(guess, big2)
+		if guess.Cmp(prevGuess) == 0 {
+			break
+		}
+	}
+	return guess
+}
+
+// EndomorphismVectors runs the first 3 steps of algorithm 3.74 from [GECC] to
+// generate the linearly independent vectors needed to generate a balanced
+// length-two representation of a multiplier such that k = k1 + k2λ (mod N) and
+// returns them.  Since the values will always be the same given the fact that N
+// and λ are fixed, the final results can be accelerated by storing the
+// precomputed values.
+func EndomorphismVectors() (a1, b1, a2, b2 *big.Int) {
+	bigMinus1 := big.NewInt(-1)
+
+	// This section uses an extended Euclidean algorithm to generate a
+	// sequence of equations:
+	//  s[i] * N + t[i] * λ = r[i]
+
+	nSqrt := sqrt(curveParams.N)
+	u, v := new(big.Int).Set(curveParams.N), new(big.Int).Set(endomorphismLambda)
+	x1, y1 := big.NewInt(1), big.NewInt(0)
+	x2, y2 := big.NewInt(0), big.NewInt(1)
+	q, r := new(big.Int), new(big.Int)
+	qu, qx1, qy1 := new(big.Int), new(big.Int), new(big.Int)
+	s, t := new(big.Int), new(big.Int)
+	ri, ti := new(big.Int), new(big.Int)
+	a1, b1, a2, b2 = new(big.Int), new(big.Int), new(big.Int), new(big.Int)
+	found, oneMore := false, false
+	for u.Sign() != 0 {
+		// q = v/u
+		q.Div(v, u)
+
+		// r = v - q*u
+		qu.Mul(q, u)
+		r.Sub(v, qu)
+
+		// s = x2 - q*x1
+		qx1.Mul(q, x1)
+		s.Sub(x2, qx1)
+
+		// t = y2 - q*y1
+		qy1.Mul(q, y1)
+		t.Sub(y2, qy1)
+
+		// v = u, u = r, x2 = x1, x1 = s, y2 = y1, y1 = t
+		v.Set(u)
+		u.Set(r)
+		x2.Set(x1)
+		x1.Set(s)
+		y2.Set(y1)
+		y1.Set(t)
+
+		// As soon as the remainder is less than the sqrt of n, the
+		// values of a1 and b1 are known.
+		if !found && r.Cmp(nSqrt) < 0 {
+			// When this condition executes ri and ti represent the
+			// r[i] and t[i] values such that i is the greatest
+			// index for which r >= sqrt(n).  Meanwhile, the current
+			// r and t values are r[i+1] and t[i+1], respectively.
+
+			// a1 = r[i+1], b1 = -t[i+1]
+			a1.Set(r)
+			b1.Mul(t, bigMinus1)
+			found = true
+			oneMore = true
+
+			// Skip to the next iteration so ri and ti are not
+			// modified.
+			continue
+
+		} else if oneMore {
+			// When this condition executes ri and ti still
+			// represent the r[i] and t[i] values while the current
+			// r and t are r[i+2] and t[i+2], respectively.
+
+			// sum1 = r[i]^2 + t[i]^2
+			rSquared := new(big.Int).Mul(ri, ri)
+			tSquared := new(big.Int).Mul(ti, ti)
+			sum1 := new(big.Int).Add(rSquared, tSquared)
+
+			// sum2 = r[i+2]^2 + t[i+2]^2
+			r2Squared := new(big.Int).Mul(r, r)
+			t2Squared := new(big.Int).Mul(t, t)
+			sum2 := new(big.Int).Add(r2Squared, t2Squared)
+
+			// if (r[i]^2 + t[i]^2) <= (r[i+2]^2 + t[i+2]^2)
+			if sum1.Cmp(sum2) <= 0 {
+				// a2 = r[i], b2 = -t[i]
+				a2.Set(ri)
+				b2.Mul(ti, bigMinus1)
+			} else {
+				// a2 = r[i+2], b2 = -t[i+2]
+				a2.Set(r)
+				b2.Mul(t, bigMinus1)
+			}
+
+			// All done.
+			break
+		}
+
+		ri.Set(r)
+		ti.Set(t)
+	}
+
+	return a1, b1, a2, b2
+}