diff options
Diffstat (limited to 'crypto/src/math/ec/custom/sec/SecP128R1Field.cs')
| -rw-r--r-- | crypto/src/math/ec/custom/sec/SecP128R1Field.cs | 90 |
1 files changed, 86 insertions, 4 deletions
diff --git a/crypto/src/math/ec/custom/sec/SecP128R1Field.cs b/crypto/src/math/ec/custom/sec/SecP128R1Field.cs index cf91c7e5d..23ea361a0 100644 --- a/crypto/src/math/ec/custom/sec/SecP128R1Field.cs +++ b/crypto/src/math/ec/custom/sec/SecP128R1Field.cs @@ -1,15 +1,17 @@ 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 SecP128R1Field { // 2^128 - 2^97 - 1 - internal static readonly uint[] P = new uint[] { 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFD }; - internal static readonly uint[] PExt = new uint[] { 0x00000001, 0x00000000, 0x00000000, 0x00000004, 0xFFFFFFFE, + internal static readonly uint[] P = new uint[]{ 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFD }; + private static readonly uint[] PExt = new uint[]{ 0x00000001, 0x00000000, 0x00000000, 0x00000004, 0xFFFFFFFE, 0xFFFFFFFF, 0x00000003, 0xFFFFFFFC }; private static readonly uint[] PExtInv = new uint[]{ 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFB, 0x00000001, 0x00000000, 0xFFFFFFFC, 0x00000003 }; @@ -66,6 +68,66 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec } } + public static void Inv(uint[] x, uint[] z) + { + /* + * Raise this element to the exponent 2^128 - 2^97 - 3 + * + * Breaking up the exponent's binary representation into "repunits", we get: + * { 30 1s } { 1 0s } { 95 1s } { 1 0s } { 1 1s } + * + * We use an addition chain for the beginning: [1], 2, 3, [5], 10, 20, [30] + */ + + if (0 != IsZero(x)) + throw new ArgumentException("cannot be 0", "x"); + + uint[] x1 = x; + uint[] x2 = Nat128.Create(); + Square(x1, x2); + Multiply(x2, x1, x2); + uint[] x3 = Nat128.Create(); + Square(x2, x3); + Multiply(x3, x1, x3); + uint[] x5 = x3; + SquareN(x3, 2, x5); + Multiply(x5, x2, x5); + uint[] x10 = x2; + SquareN(x5, 5, x10); + Multiply(x10, x5, x10); + uint[] x20 = Nat128.Create(); + SquareN(x10, 10, x20); + Multiply(x20, x10, x20); + uint[] x30 = x20; + SquareN(x20, 10, x30); + Multiply(x30, x10, x30); + + uint[] t = x10; + SquareN(x30, 31, t); + Multiply(t, x30, t); + SquareN(t, 30, t); + Multiply(t, x30, t); + SquareN(t, 30, t); + Multiply(t, x30, t); + SquareN(t, 5, t); + Multiply(t, x5, 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 < 4; ++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 = Nat128.CreateExt(); @@ -84,9 +146,9 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec public static void Negate(uint[] x, uint[] z) { - if (Nat128.IsZero(x)) + if (0 != IsZero(x)) { - Nat128.Zero(z); + Nat128.Sub(P, P, z); } else { @@ -94,6 +156,26 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec } } + public static void Random(SecureRandom r, uint[] z) + { + byte[] bb = new byte[4 * 4]; + do + { + r.NextBytes(bb); + Pack.LE_To_UInt32(bb, 0, z, 0, 4); + } + while (0 == Nat.LessThan(4, 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 x0 = xx[0], x1 = xx[1], x2 = xx[2], x3 = xx[3]; |