From 8405b5610adc2405c7cb1d2b25150388728adba6 Mon Sep 17 00:00:00 2001 From: Peter Dettman Date: Sat, 1 Feb 2014 19:10:28 +0700 Subject: Add custom curve for secp521r1 (P-521) --- crypto/src/math/ec/ECFieldElement.cs | 9 +- crypto/src/math/ec/Mod.cs | 9 +- crypto/src/math/ec/Nat.cs | 146 ++++------- crypto/src/math/ec/custom/sec/SecP521R1Curve.cs | 95 +++++++ crypto/src/math/ec/custom/sec/SecP521R1Field.cs | 131 ++++++++++ .../math/ec/custom/sec/SecP521R1FieldElement.cs | 166 ++++++++++++ crypto/src/math/ec/custom/sec/SecP521R1Point.cs | 287 +++++++++++++++++++++ 7 files changed, 734 insertions(+), 109 deletions(-) create mode 100644 crypto/src/math/ec/custom/sec/SecP521R1Curve.cs create mode 100644 crypto/src/math/ec/custom/sec/SecP521R1Field.cs create mode 100644 crypto/src/math/ec/custom/sec/SecP521R1FieldElement.cs create mode 100644 crypto/src/math/ec/custom/sec/SecP521R1Point.cs (limited to 'crypto/src/math/ec') diff --git a/crypto/src/math/ec/ECFieldElement.cs b/crypto/src/math/ec/ECFieldElement.cs index 13ae32e5d..7a4c9da97 100644 --- a/crypto/src/math/ec/ECFieldElement.cs +++ b/crypto/src/math/ec/ECFieldElement.cs @@ -390,11 +390,10 @@ namespace Org.BouncyCastle.Math.EC protected virtual BigInteger ModInverse(BigInteger x) { - // Our BigInteger.ModInverse performance is quite poor, so use the new Nat/Mod classes here - //return x.ModInverse(q); - int len = (FieldSize + 31) >> 5; - uint[] p = Nat.FromBigInteger(len, q); - uint[] n = Nat.FromBigInteger(len, x); + int bits = FieldSize; + int len = (bits + 31) >> 5; + uint[] p = Nat.FromBigInteger(bits, q); + uint[] n = Nat.FromBigInteger(bits, x); uint[] z = Nat.Create(len); Mod.Invert(p, n, z); return Nat.ToBigInteger(len, z); diff --git a/crypto/src/math/ec/Mod.cs b/crypto/src/math/ec/Mod.cs index bfb2faea4..a05ff77aa 100644 --- a/crypto/src/math/ec/Mod.cs +++ b/crypto/src/math/ec/Mod.cs @@ -101,7 +101,7 @@ namespace Org.BouncyCastle.Math.EC int count = 0; while (u[0] == 0) { - Nat.ShiftDownWord(u, uLen, 0); + Nat.ShiftDownWord(uLen, u, 0); count += 32; } @@ -109,7 +109,7 @@ namespace Org.BouncyCastle.Math.EC int zeroes = GetTrailingZeroes(u[0]); if (zeroes > 0) { - Nat.ShiftDownBits(u, uLen, zeroes, 0); + Nat.ShiftDownBits(uLen, u, zeroes, 0); count += zeroes; } } @@ -129,14 +129,13 @@ namespace Org.BouncyCastle.Math.EC } Debug.Assert(xc == 0 || xc == -1); - Nat.ShiftDownBit(x, len, (uint)xc); + Nat.ShiftDownBit(len, x, (uint)xc); } } private static int GetTrailingZeroes(uint x) { - // assert x != 0; - + Debug.Assert(x != 0); int count = 0; while ((x & 1) == 0) { diff --git a/crypto/src/math/ec/Nat.cs b/crypto/src/math/ec/Nat.cs index 593cb4ecf..b0213fb97 100644 --- a/crypto/src/math/ec/Nat.cs +++ b/crypto/src/math/ec/Nat.cs @@ -46,19 +46,6 @@ namespace Org.BouncyCastle.Math.EC return c == 0 ? 0 : Inc(len, z, zOff + 2); } - public static uint AddExt(int len, uint[] xx, uint[] yy, uint[] zz) - { - int extLen = len << 1; - ulong c = 0; - for (int i = 0; i < extLen; ++i) - { - c += (ulong)xx[i] + yy[i]; - zz[i] = (uint)c; - c >>= 32; - } - return (uint)c; - } - public static uint AddToExt(int len, uint[] x, int xOff, uint[] zz, int zzOff) { Debug.Assert(zzOff <= len); @@ -79,7 +66,7 @@ namespace Org.BouncyCastle.Math.EC ulong c = (ulong)x + zz[zzOff]; zz[zzOff] = (uint)c; c >>= 32; - return c == 0 ? 0 : IncExt(len, zz, zzOff + 1); + return c == 0 ? 0 : Inc(extLen, zz, zzOff + 1); } public static uint[] Copy(int len, uint[] x) @@ -94,12 +81,6 @@ namespace Org.BouncyCastle.Math.EC return new uint[len]; } - public static uint[] CreateExt(int len) - { - int extLen = len << 1; - return new uint[extLen]; - } - public static int Dec(int len, uint[] z, int zOff) { Debug.Assert(zOff <= len); @@ -113,11 +94,24 @@ namespace Org.BouncyCastle.Math.EC return -1; } - public static uint[] FromBigInteger(int len, BigInteger x) + public static bool Eq(int len, uint[] x, uint[] y) + { + for (int i = len - 1; i >= 0; --i) + { + if (x[i] != y[i]) + { + return false; + } + } + return true; + } + + public static uint[] FromBigInteger(int bits, BigInteger x) { - if (x.SignValue < 0 || x.BitLength > (len << 5)) + if (x.SignValue < 0 || x.BitLength > bits) throw new ArgumentException(); + int len = (bits + 31) >> 5; uint[] z = Create(len); int i = 0; while (x.SignValue != 0) @@ -156,20 +150,6 @@ namespace Org.BouncyCastle.Math.EC return true; } - public static bool GteExt(int len, uint[] xx, uint[] yy) - { - int extLen = len << 1; - for (int i = extLen - 1; i >= 0; --i) - { - uint xx_i = xx[i], yy_i = yy[i]; - if (xx_i < yy_i) - return false; - if (xx_i > yy_i) - return true; - } - return true; - } - public static uint Inc(int len, uint[] z, int zOff) { Debug.Assert(zOff <= len); @@ -183,20 +163,6 @@ namespace Org.BouncyCastle.Math.EC return 1; } - public static uint IncExt(int len, uint[] zz, int zzOff) - { - int extLen = len << 1; - Debug.Assert(zzOff <= extLen); - for (int i = zzOff; i < extLen; ++i) - { - if (++zz[i] != uint.MinValue) - { - return 0; - } - } - return 1; - } - public static bool IsOne(int len, uint[] x) { if (x[0] != 1) @@ -229,42 +195,24 @@ namespace Org.BouncyCastle.Math.EC return true; } - public static bool IsZeroExt(int len, uint[] xx) - { - if (xx[0] != 0) - { - return false; - } - int extLen = len << 1; - for (int i = 1; i < extLen; ++i) - { - if (xx[i] != 0) - { - return false; - } - } - return true; - } - public static void Mul(int len, uint[] x, uint[] y, uint[] zz) { zz[len] = (uint)MulWordExt(len, x[0], y, zz, 0); for (int i = 1; i < len; ++i) { - zz[i + len] = (uint)MulWordAddExt(len, x[i], y, 0, zz, i); + zz[i + len] = (uint)MulWordAddExt(len, x[i], y, zz, i); } } - public static uint MulWordAddExt(int len, uint x, uint[] yy, int yyOff, uint[] zz, int zzOff) + public static uint MulWordAddExt(int len, uint x, uint[] y, uint[] zz, int zzOff) { - Debug.Assert(yyOff <= len); Debug.Assert(zzOff <= len); ulong c = 0, xVal = (ulong)x; int i = 0; do { - c += xVal * yy[yyOff + i] + zz[zzOff + i]; + c += xVal * y[i] + zz[zzOff + i]; zz[zzOff + i] = (uint)c; c >>= 32; } @@ -303,13 +251,13 @@ namespace Org.BouncyCastle.Math.EC return (uint)c; } - public static uint ShiftDownBit(uint[] x, int xLen, uint c) + public static uint ShiftDownBit(int len, uint[] z, uint c) { - int i = xLen; + int i = len; while (--i >= 0) { - uint next = x[i]; - x[i] = (next >> 1) | (c << 31); + uint next = z[i]; + z[i] = (next >> 1) | (c << 31); c = next; } return c << 31; @@ -327,10 +275,10 @@ namespace Org.BouncyCastle.Math.EC return c << 31; } - public static uint ShiftDownBits(uint[] x, int xLen, int bits, uint c) + public static uint ShiftDownBits(int len, uint[] x, int bits, uint c) { Debug.Assert(bits > 0 && bits < 32); - int i = xLen; + int i = len; while (--i >= 0) { uint next = x[i]; @@ -340,24 +288,37 @@ namespace Org.BouncyCastle.Math.EC return c << -bits; } - public static uint ShiftDownWord(uint[] x, int xLen, uint c) + public static uint ShiftDownBitsExt(int len, uint[] xx, int xxOff, int bits, uint c, uint[] z) { - int i = xLen; + Debug.Assert(bits > 0 && bits < 32); + int i = len; while (--i >= 0) { - uint next = x[i]; - x[i] = c; + uint next = xx[xxOff + i]; + z[i] = (next >> bits) | (c << -bits); + c = next; + } + return c << -bits; + } + + public static uint ShiftDownWord(int len, uint[] z, uint c) + { + int i = len; + while (--i >= 0) + { + uint next = z[i]; + z[i] = c; c = next; } return c; } - public static uint ShiftUpBit(uint[] x, int xLen, uint c) + public static uint ShiftUpBit(int len, uint[] z, uint c) { - for (int i = 0; i < xLen; ++i) + for (int i = 0; i < len; ++i) { - uint next = x[i]; - x[i] = (next << 1) | (c >> 31); + uint next = z[i]; + z[i] = (next << 1) | (c >> 31); c = next; } return c >> 31; @@ -395,7 +356,7 @@ namespace Org.BouncyCastle.Math.EC AddWordExt(len, c, zz, i << 1); } - ShiftUpBit(zz, extLen, x[0] << 31); + ShiftUpBit(extLen, zz, x[0] << 31); } public static uint SquareWordAddExt(int len, uint[] x, int xPos, uint[] zz) @@ -451,19 +412,6 @@ namespace Org.BouncyCastle.Math.EC return c == 0 ? 0 : Dec(len, z, 2); } - public static int SubExt(int len, uint[] xx, uint[] yy, uint[] zz) - { - int extLen = len << 1; - long c = 0; - for (int i = 0; i < extLen; ++i) - { - c += (long)xx[i] - yy[i]; - zz[i] = (uint)c; - c >>= 32; - } - return (int)c; - } - public static int SubFromExt(int len, uint[] x, int xOff, uint[] zz, int zzOff) { Debug.Assert(zzOff <= len); diff --git a/crypto/src/math/ec/custom/sec/SecP521R1Curve.cs b/crypto/src/math/ec/custom/sec/SecP521R1Curve.cs new file mode 100644 index 000000000..24a0a5e33 --- /dev/null +++ b/crypto/src/math/ec/custom/sec/SecP521R1Curve.cs @@ -0,0 +1,95 @@ +using System; + +using Org.BouncyCastle.Math.Field; +using Org.BouncyCastle.Utilities.Encoders; + +namespace Org.BouncyCastle.Math.EC.Custom.Sec +{ + internal class SecP521R1Curve + : ECCurve + { + public static readonly BigInteger q = new BigInteger(1, + Hex.Decode("01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF")); + + private const int SecP521R1_DEFAULT_COORDS = COORD_JACOBIAN; + + protected readonly SecP521R1Point m_infinity; + + public SecP521R1Curve() + : base(FiniteFields.GetPrimeField(q)) + { + this.m_infinity = new SecP521R1Point(this, null, null); + + this.m_a = FromBigInteger(new BigInteger(1, + Hex.Decode("01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFC"))); + this.m_b = FromBigInteger(new BigInteger(1, + Hex.Decode("0051953EB9618E1C9A1F929A21A0B68540EEA2DA725B99B315F3B8B489918EF109E156193951EC7E937B1652C0BD3BB1BF073573DF883D2C34F1EF451FD46B503F00"))); + this.m_order = new BigInteger(1, Hex.Decode("01FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFA51868783BF2F966B7FCC0148F709A5D03BB5C9B8899C47AEBB6FB71E91386409")); + this.m_cofactor = BigInteger.One; + this.m_coord = SecP521R1_DEFAULT_COORDS; + } + + protected override ECCurve CloneCurve() + { + return new SecP521R1Curve(); + } + + public override bool SupportsCoordinateSystem(int coord) + { + switch (coord) + { + case COORD_JACOBIAN: + return true; + default: + return false; + } + } + + public virtual BigInteger Q + { + get { return q; } + } + + public override ECPoint Infinity + { + get { return m_infinity; } + } + + public override int FieldSize + { + get { return q.BitLength; } + } + + public override ECFieldElement FromBigInteger(BigInteger x) + { + return new SecP521R1FieldElement(x); + } + + protected internal override ECPoint CreateRawPoint(ECFieldElement x, ECFieldElement y, bool withCompression) + { + return new SecP521R1Point(this, x, y, withCompression); + } + + protected override ECPoint DecompressPoint(int yTilde, BigInteger X1) + { + ECFieldElement x = FromBigInteger(X1); + ECFieldElement alpha = x.Square().Add(A).Multiply(x).Add(B); + ECFieldElement beta = alpha.Sqrt(); + + // + // if we can't find a sqrt we haven't got a point on the + // curve - run! + // + if (beta == null) + throw new ArithmeticException("Invalid point compression"); + + if (beta.TestBitZero() != (yTilde == 1)) + { + // Use the other root + beta = beta.Negate(); + } + + return new SecP521R1Point(this, x, beta, true); + } + } +} diff --git a/crypto/src/math/ec/custom/sec/SecP521R1Field.cs b/crypto/src/math/ec/custom/sec/SecP521R1Field.cs new file mode 100644 index 000000000..43f012b8b --- /dev/null +++ b/crypto/src/math/ec/custom/sec/SecP521R1Field.cs @@ -0,0 +1,131 @@ +using System; +using System.Diagnostics; + +namespace Org.BouncyCastle.Math.EC.Custom.Sec +{ + internal class SecP521R1Field + { + // 2^521 - 1 + internal static readonly uint[] P = new uint[]{ 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, + 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x1FF }; + private const int P16 = 0x1FF; + + public static void Add(uint[] x, uint[] y, uint[] z) + { + uint c = Nat.Add(16, x, y, z) + x[16] + y[16]; + if (c > P16 || (c == P16 && Nat.Eq(16, z, P))) + { + c += Nat.Inc(16, z, 0); + c &= P16; + } + z[16] = c; + } + + public static void AddOne(uint[] x, uint[] z) + { + Array.Copy(x, 0, z, 0, 16); + uint c = Nat.Inc(16, z, 0) + z[16]; + if (c > P16 || (c == P16 && Nat.Eq(16, z, P))) + { + c += Nat.Inc(16, z, 0); + c &= P16; + } + z[16] = c; + } + + public static uint[] FromBigInteger(BigInteger x) + { + uint[] z = Nat.FromBigInteger(521, x); + if (Nat.Eq(17, z, P)) + { + Nat.Zero(17, z); + } + return z; + } + + public static void Half(uint[] x, uint[] z) + { + uint c0 = x[0] & 1, x16 = x[16], c512 = x16 & 1; + Nat.ShiftDownBit(16, x, c512, z); + z[16] = (x16 >> 1) | (c0 << 8); + } + + public static void Multiply(uint[] x, uint[] y, uint[] z) + { + uint[] tt = Nat.Create(34); + Nat.Mul(17, x, y, tt); + Reduce(tt, z); + } + + public static void Negate(uint[] x, uint[] z) + { + if (Nat.IsZero(17, x)) + { + Nat.Zero(17, z); + } + else + { + Nat.Sub(17, P, x, z); + } + } + + public static void Reduce(uint[] xx, uint[] z) + { + Debug.Assert(xx[33] == 0); + Debug.Assert(xx[32] >> 18 == 0); + uint xx32 = xx[32]; + uint c = Nat.ShiftDownBitsExt(16, xx, 16, 9, xx32, z) >> 23; + c += xx32 >> 9; + c += Nat.Add(16, z, xx, z); + if (c > P16 || (c == P16 && Nat.Eq(16, z, P))) + { + c += Nat.Inc(16, z, 0); + c &= P16; + } + z[16] = c; + } + + public static void Square(uint[] x, uint[] z) + { + uint[] tt = Nat.Create(34); + Nat.Square(17, x, tt); + Reduce(tt, z); + } + + public static void SquareN(uint[] x, int n, uint[] z) + { + Debug.Assert(n > 0); + uint[] tt = Nat.Create(34); + Nat.Square(17, x, tt); + Reduce(tt, z); + + while (--n > 0) + { + Nat.Square(17, z, tt); + Reduce(tt, z); + } + } + + public static void Subtract(uint[] x, uint[] y, uint[] z) + { + int c = Nat.Sub(16, x, y, z) + (int)(x[16] - y[16]); + if (c < 0) + { + c += Nat.Dec(16, z, 0); + c &= P16; + } + z[16] = (uint)c; + } + + public static void Twice(uint[] x, uint[] z) + { + uint c = Nat.ShiftUpBit(16, x, 0, z) | (x[16] << 1); + if (c > P16 || (c == P16 && Nat.Eq(16, z, P))) + { + c += Nat.Inc(16, z, 0); + c &= P16; + } + z[16] = c; + } + } +} diff --git a/crypto/src/math/ec/custom/sec/SecP521R1FieldElement.cs b/crypto/src/math/ec/custom/sec/SecP521R1FieldElement.cs new file mode 100644 index 000000000..e47a199f3 --- /dev/null +++ b/crypto/src/math/ec/custom/sec/SecP521R1FieldElement.cs @@ -0,0 +1,166 @@ +using System; + +using Org.BouncyCastle.Utilities; + +namespace Org.BouncyCastle.Math.EC.Custom.Sec +{ + internal class SecP521R1FieldElement + : ECFieldElement + { + public static readonly BigInteger Q = SecP521R1Curve.q; + + protected internal readonly uint[] x; + + public SecP521R1FieldElement(BigInteger x) + { + if (x == null || x.SignValue < 0 || x.CompareTo(Q) >= 0) + throw new ArgumentException("value invalid for SecP521R1FieldElement", "x"); + + this.x = SecP521R1Field.FromBigInteger(x); + } + + public SecP521R1FieldElement() + { + this.x = Nat.Create(17); + } + + protected internal SecP521R1FieldElement(uint[] x) + { + this.x = x; + } + + public override bool IsZero + { + get { return Nat.IsZero(17, x); } + } + + public override bool IsOne + { + get { return Nat.IsOne(17, x); } + } + + public override bool TestBitZero() + { + return Nat.GetBit(x, 0) == 1; + } + + public override BigInteger ToBigInteger() + { + return Nat.ToBigInteger(17, x); + } + + public override string FieldName + { + get { return "SecP521R1Field"; } + } + + public override int FieldSize + { + get { return Q.BitLength; } + } + + public override ECFieldElement Add(ECFieldElement b) + { + uint[] z = Nat.Create(17); + SecP521R1Field.Add(x, ((SecP521R1FieldElement)b).x, z); + return new SecP521R1FieldElement(z); + } + + public override ECFieldElement AddOne() + { + uint[] z = Nat.Create(17); + SecP521R1Field.AddOne(x, z); + return new SecP521R1FieldElement(z); + } + + public override ECFieldElement Subtract(ECFieldElement b) + { + uint[] z = Nat.Create(17); + SecP521R1Field.Subtract(x, ((SecP521R1FieldElement)b).x, z); + return new SecP521R1FieldElement(z); + } + + public override ECFieldElement Multiply(ECFieldElement b) + { + uint[] z = Nat.Create(17); + SecP521R1Field.Multiply(x, ((SecP521R1FieldElement)b).x, z); + return new SecP521R1FieldElement(z); + } + + public override ECFieldElement Divide(ECFieldElement b) + { + //return Multiply(b.Invert()); + uint[] z = Nat.Create(17); + Mod.Invert(SecP521R1Field.P, ((SecP521R1FieldElement)b).x, z); + SecP521R1Field.Multiply(z, x, z); + return new SecP521R1FieldElement(z); + } + + public override ECFieldElement Negate() + { + uint[] z = Nat.Create(17); + SecP521R1Field.Negate(x, z); + return new SecP521R1FieldElement(z); + } + + public override ECFieldElement Square() + { + uint[] z = Nat.Create(17); + SecP521R1Field.Square(x, z); + return new SecP521R1FieldElement(z); + } + + public override ECFieldElement Invert() + { + //return new SecP521R1FieldElement(ToBigInteger().ModInverse(Q)); + uint[] z = Nat.Create(17); + Mod.Invert(SecP521R1Field.P, x, z); + return new SecP521R1FieldElement(z); + } + + /** + * return a sqrt root - the routine verifies that the calculation returns the right value - if + * none exists it returns null. + */ + public override ECFieldElement Sqrt() + { + // Raise this element to the exponent 2^519 + + uint[] x1 = this.x; + if (Nat.IsZero(17, x1) || Nat.IsOne(17, x1)) + return this; + + uint[] t1 = Nat.Create(17); + uint[] t2 = Nat.Create(17); + + SecP521R1Field.SquareN(x1, 519, t1); + SecP521R1Field.Square(t1, t2); + + return Arrays.AreEqual(x1, t2) ? new SecP521R1FieldElement(t1) : null; + } + + public override bool Equals(object obj) + { + return Equals(obj as SecP521R1FieldElement); + } + + public override bool Equals(ECFieldElement other) + { + return Equals(other as SecP521R1FieldElement); + } + + public virtual bool Equals(SecP521R1FieldElement other) + { + if (this == other) + return true; + if (null == other) + return false; + return Arrays.AreEqual(x, other.x); + } + + public override int GetHashCode() + { + return Q.GetHashCode() ^ Arrays.GetHashCode(x); + } + } +} diff --git a/crypto/src/math/ec/custom/sec/SecP521R1Point.cs b/crypto/src/math/ec/custom/sec/SecP521R1Point.cs new file mode 100644 index 000000000..5da71f078 --- /dev/null +++ b/crypto/src/math/ec/custom/sec/SecP521R1Point.cs @@ -0,0 +1,287 @@ +using System; + +namespace Org.BouncyCastle.Math.EC.Custom.Sec +{ + internal class SecP521R1Point + : ECPointBase + { + /** + * Create a point which encodes with point compression. + * + * @param curve + * the curve to use + * @param x + * affine x co-ordinate + * @param y + * affine y co-ordinate + * + * @deprecated Use ECCurve.createPoint to construct points + */ + public SecP521R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y) + : this(curve, x, y, false) + { + } + + /** + * Create a point that encodes with or without point compresion. + * + * @param curve + * the curve to use + * @param x + * affine x co-ordinate + * @param y + * affine y co-ordinate + * @param withCompression + * if true encode with point compression + * + * @deprecated per-point compression property will be removed, refer + * {@link #getEncoded(bool)} + */ + public SecP521R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, bool withCompression) + : base(curve, x, y, withCompression) + { + if ((x == null) != (y == null)) + throw new ArgumentException("Exactly one of the field elements is null"); + } + + internal SecP521R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs, bool withCompression) + : base(curve, x, y, zs, withCompression) + { + } + + protected override ECPoint Detach() + { + return new SecP521R1Point(null, AffineXCoord, AffineYCoord); + } + + protected internal override bool CompressionYTilde + { + get { return this.AffineYCoord.TestBitZero(); } + } + + public override ECPoint Add(ECPoint b) + { + if (this.IsInfinity) + return b; + if (b.IsInfinity) + return this; + if (this == b) + return Twice(); + + ECCurve curve = this.Curve; + + SecP521R1FieldElement X1 = (SecP521R1FieldElement)this.RawXCoord, Y1 = (SecP521R1FieldElement)this.RawYCoord; + SecP521R1FieldElement X2 = (SecP521R1FieldElement)b.RawXCoord, Y2 = (SecP521R1FieldElement)b.RawYCoord; + + SecP521R1FieldElement Z1 = (SecP521R1FieldElement)this.RawZCoords[0]; + SecP521R1FieldElement Z2 = (SecP521R1FieldElement)b.RawZCoords[0]; + + uint[] t1 = Nat.Create(17); + uint[] t2 = Nat.Create(17); + uint[] t3 = Nat.Create(17); + uint[] t4 = Nat.Create(17); + + bool Z1IsOne = Z1.IsOne; + uint[] U2, S2; + if (Z1IsOne) + { + U2 = X2.x; + S2 = Y2.x; + } + else + { + S2 = t3; + SecP521R1Field.Square(Z1.x, S2); + + U2 = t2; + SecP521R1Field.Multiply(S2, X2.x, U2); + + SecP521R1Field.Multiply(S2, Z1.x, S2); + SecP521R1Field.Multiply(S2, Y2.x, S2); + } + + bool Z2IsOne = Z2.IsOne; + uint[] U1, S1; + if (Z2IsOne) + { + U1 = X1.x; + S1 = Y1.x; + } + else + { + S1 = t4; + SecP521R1Field.Square(Z2.x, S1); + + U1 = t1; + SecP521R1Field.Multiply(S1, X1.x, U1); + + SecP521R1Field.Multiply(S1, Z2.x, S1); + SecP521R1Field.Multiply(S1, Y1.x, S1); + } + + uint[] H = Nat.Create(17); + SecP521R1Field.Subtract(U1, U2, H); + + uint[] R = t2; + SecP521R1Field.Subtract(S1, S2, R); + + // Check if b == this or b == -this + if (Nat.IsZero(17, H)) + { + if (Nat.IsZero(17, R)) + { + // this == b, i.e. this must be doubled + return this.Twice(); + } + + // this == -b, i.e. the result is the point at infinity + return curve.Infinity; + } + + uint[] HSquared = t3; + SecP521R1Field.Square(H, HSquared); + + uint[] G = Nat.Create(17); + SecP521R1Field.Multiply(HSquared, H, G); + + uint[] V = t3; + SecP521R1Field.Multiply(HSquared, U1, V); + + SecP521R1Field.Multiply(S1, G, t1); + + SecP521R1FieldElement X3 = new SecP521R1FieldElement(t4); + SecP521R1Field.Square(R, X3.x); + SecP521R1Field.Add(X3.x, G, X3.x); + SecP521R1Field.Subtract(X3.x, V, X3.x); + SecP521R1Field.Subtract(X3.x, V, X3.x); + + SecP521R1FieldElement Y3 = new SecP521R1FieldElement(G); + SecP521R1Field.Subtract(V, X3.x, Y3.x); + SecP521R1Field.Multiply(Y3.x, R, t2); + SecP521R1Field.Subtract(t2, t1, Y3.x); + + SecP521R1FieldElement Z3 = new SecP521R1FieldElement(H); + if (!Z1IsOne) + { + SecP521R1Field.Multiply(Z3.x, Z1.x, Z3.x); + } + if (!Z2IsOne) + { + SecP521R1Field.Multiply(Z3.x, Z2.x, Z3.x); + } + + ECFieldElement[] zs = new ECFieldElement[] { Z3 }; + + return new SecP521R1Point(curve, X3, Y3, zs, IsCompressed); + } + + public override ECPoint Twice() + { + if (this.IsInfinity) + return this; + + ECCurve curve = this.Curve; + + SecP521R1FieldElement Y1 = (SecP521R1FieldElement)this.RawYCoord; + if (Y1.IsZero) + return curve.Infinity; + + SecP521R1FieldElement X1 = (SecP521R1FieldElement)this.RawXCoord, Z1 = (SecP521R1FieldElement)this.RawZCoords[0]; + + uint[] t1 = Nat.Create(17); + uint[] t2 = Nat.Create(17); + + uint[] Y1Squared = Nat.Create(17); + SecP521R1Field.Square(Y1.x, Y1Squared); + + uint[] T = Nat.Create(17); + SecP521R1Field.Square(Y1Squared, T); + + bool Z1IsOne = Z1.IsOne; + + uint[] Z1Squared = Z1.x; + if (!Z1IsOne) + { + Z1Squared = t2; + SecP521R1Field.Square(Z1.x, Z1Squared); + } + + SecP521R1Field.Subtract(X1.x, Z1Squared, t1); + + uint[] M = t2; + SecP521R1Field.Add(X1.x, Z1Squared, M); + SecP521R1Field.Multiply(M, t1, M); + SecP521R1Field.Twice(M, t1); + SecP521R1Field.Add(M, t1, M); + + uint[] S = Y1Squared; + SecP521R1Field.Multiply(Y1Squared, X1.x, S); + SecP521R1Field.Twice(S, S); + SecP521R1Field.Twice(S, S); + + SecP521R1Field.Twice(T, t1); + SecP521R1Field.Twice(t1, t1); + SecP521R1Field.Twice(t1, t1); + + SecP521R1FieldElement X3 = new SecP521R1FieldElement(T); + SecP521R1Field.Square(M, X3.x); + SecP521R1Field.Subtract(X3.x, S, X3.x); + SecP521R1Field.Subtract(X3.x, S, X3.x); + + SecP521R1FieldElement Y3 = new SecP521R1FieldElement(S); + SecP521R1Field.Subtract(S, X3.x, Y3.x); + SecP521R1Field.Multiply(Y3.x, M, Y3.x); + SecP521R1Field.Subtract(Y3.x, t1, Y3.x); + + SecP521R1FieldElement Z3 = new SecP521R1FieldElement(M); + SecP521R1Field.Twice(Y1.x, Z3.x); + if (!Z1IsOne) + { + SecP521R1Field.Multiply(Z3.x, Z1.x, Z3.x); + } + + return new SecP521R1Point(curve, X3, Y3, new ECFieldElement[] { Z3 }, IsCompressed); + } + + public override ECPoint TwicePlus(ECPoint b) + { + if (this == b) + return ThreeTimes(); + if (this.IsInfinity) + return b; + if (b.IsInfinity) + return Twice(); + + ECFieldElement Y1 = this.RawYCoord; + if (Y1.IsZero) + return b; + + return Twice().Add(b); + } + + public override ECPoint ThreeTimes() + { + if (this.IsInfinity || this.RawYCoord.IsZero) + return this; + + // NOTE: Be careful about recursions between TwicePlus and ThreeTimes + return Twice().Add(this); + } + + public override ECPoint Subtract(ECPoint b) + { + if (b.IsInfinity) + return this; + + return Add(b.Negate()); + } + + public override ECPoint Negate() + { + if (IsInfinity) + return this; + + return new SecP521R1Point(Curve, RawXCoord, RawYCoord.Negate(), RawZCoords, IsCompressed); + } + } +} -- cgit 1.4.1