diff options
Diffstat (limited to 'crypto/src/math/ec/custom/sec/SecP256K1Field.cs')
| -rw-r--r-- | crypto/src/math/ec/custom/sec/SecP256K1Field.cs | 104 |
1 files changed, 100 insertions, 4 deletions
diff --git a/crypto/src/math/ec/custom/sec/SecP256K1Field.cs b/crypto/src/math/ec/custom/sec/SecP256K1Field.cs index b0646e93f..1f11c9c78 100644 --- a/crypto/src/math/ec/custom/sec/SecP256K1Field.cs +++ b/crypto/src/math/ec/custom/sec/SecP256K1Field.cs @@ -1,16 +1,18 @@ using System; using System.Diagnostics; +using Org.BouncyCastle.Crypto.Utilities; using Org.BouncyCastle.Math.Raw; +using Org.BouncyCastle.Security; namespace Org.BouncyCastle.Math.EC.Custom.Sec { internal class SecP256K1Field { // 2^256 - 2^32 - 2^9 - 2^8 - 2^7 - 2^6 - 2^4 - 1 - internal static readonly uint[] P = new uint[]{ 0xFFFFFC2F, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, + private static readonly uint[] P = new uint[]{ 0xFFFFFC2F, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF }; - internal static readonly uint[] PExt = new uint[]{ 0x000E90A1, 0x000007A2, 0x00000001, 0x00000000, 0x00000000, + private static readonly uint[] PExt = new uint[]{ 0x000E90A1, 0x000007A2, 0x00000001, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0xFFFFF85E, 0xFFFFFFFD, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF }; private static readonly uint[] PExtInv = new uint[]{ 0xFFF16F5F, 0xFFFFF85D, 0xFFFFFFFE, 0xFFFFFFFF, 0xFFFFFFFF, @@ -72,6 +74,80 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec } } + public static void Inv(uint[] x, uint[] z) + { + /* + * Raise this element to the exponent 2^256 - 2^32 - 2^9 - 2^8 - 2^7 - 2^6 - 2^4 - 3 + * + * Breaking up the exponent's binary representation into "repunits", we get: + * { 223 1s } { 1 0s } { 22 1s } { 4 0s } { 1 1s } { 1 0s } { 2 1s } { 1 0s } { 1 1s } + * + * Therefore we need an addition chain containing 1, 2, 22, 223 (the lengths of the repunits) + * We use: [1], [2], 3, 6, 9, 11, [22], 44, 88, 176, 220, [223] + */ + + if (0 != IsZero(x)) + throw new ArgumentException("cannot be 0", "x"); + + uint[] x1 = x; + uint[] x2 = Nat256.Create(); + Square(x1, x2); + Multiply(x2, x1, x2); + uint[] x3 = Nat256.Create(); + Square(x2, x3); + Multiply(x3, x1, x3); + uint[] x6 = Nat256.Create(); + SquareN(x3, 3, x6); + Multiply(x6, x3, x6); + uint[] x9 = x6; + SquareN(x6, 3, x9); + Multiply(x9, x3, x9); + uint[] x11 = x9; + SquareN(x9, 2, x11); + Multiply(x11, x2, x11); + uint[] x22 = Nat256.Create(); + SquareN(x11, 11, x22); + Multiply(x22, x11, x22); + uint[] x44 = x11; + SquareN(x22, 22, x44); + Multiply(x44, x22, x44); + uint[] x88 = Nat256.Create(); + SquareN(x44, 44, x88); + Multiply(x88, x44, x88); + uint[] x176 = Nat256.Create(); + SquareN(x88, 88, x176); + Multiply(x176, x88, x176); + uint[] x220 = x88; + SquareN(x176, 44, x220); + Multiply(x220, x44, x220); + uint[] x223 = x44; + SquareN(x220, 3, x223); + Multiply(x223, x3, x223); + + uint[] t = x223; + SquareN(t, 23, t); + Multiply(t, x22, t); + SquareN(t, 5, t); + Multiply(t, x1, t); + SquareN(t, 3, t); + Multiply(t, x2, t); + SquareN(t, 2, t); + + // NOTE that x1 and z could be the same array + Multiply(x1, t, z); + } + + public static int IsZero(uint[] x) + { + uint d = 0; + for (int i = 0; i < 8; ++i) + { + d |= x[i]; + } + d = (d >> 1) | (d & 1); + return ((int)d - 1) >> 31; + } + public static void Multiply(uint[] x, uint[] y, uint[] z) { uint[] tt = Nat256.CreateExt(); @@ -93,9 +169,9 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec public static void Negate(uint[] x, uint[] z) { - if (Nat256.IsZero(x)) + if (0 != IsZero(x)) { - Nat256.Zero(z); + Nat256.Sub(P, P, z); } else { @@ -103,6 +179,26 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec } } + public static void Random(SecureRandom r, uint[] z) + { + byte[] bb = new byte[8 * 4]; + do + { + r.NextBytes(bb); + Pack.LE_To_UInt32(bb, 0, z, 0, 8); + } + while (0 == Nat.LessThan(8, z, P)); + } + + public static void RandomMult(SecureRandom r, uint[] z) + { + do + { + Random(r, z); + } + while (0 != IsZero(z)); + } + public static void Reduce(uint[] xx, uint[] z) { ulong cc = Nat256.Mul33Add(PInv33, xx, 8, xx, 0, z, 0); |