diff options
Diffstat (limited to 'crypto/src/math/ec/custom/sec/SecP256R1Field.cs')
| -rw-r--r-- | crypto/src/math/ec/custom/sec/SecP256R1Field.cs | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/crypto/src/math/ec/custom/sec/SecP256R1Field.cs b/crypto/src/math/ec/custom/sec/SecP256R1Field.cs new file mode 100644 index 000000000..baea02dd0 --- /dev/null +++ b/crypto/src/math/ec/custom/sec/SecP256R1Field.cs @@ -0,0 +1,175 @@ +using System; +using System.Diagnostics; + +namespace Org.BouncyCastle.Math.EC.Custom.Sec +{ + internal class SecP256R1Field + { + // 2^256 - 2^224 + 2^192 + 2^96 - 1 + internal static readonly uint[] P = new uint[]{ 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0x00000000, 0x00000000, + 0x00000001, 0xFFFFFFFF }; + private const uint P7 = 0xFFFFFFFF; + private static readonly uint[] PExt = new uint[]{ 0x00000001, 0x00000000, 0x00000000, 0xFFFFFFFE, 0xFFFFFFFF, + 0xFFFFFFFF, 0xFFFFFFFE, 0x00000001, 0xFFFFFFFE, 0x00000001, 0xFFFFFFFE, 0x00000001, 0x00000001, 0xFFFFFFFE, + 0x00000002, 0xFFFFFFFE }; + + public static void Add(uint[] x, uint[] y, uint[] z) + { + uint c = Nat256.Add(x, y, z); + if (c != 0 || (z[7] == P7 && Nat256.Gte(z, P))) + { + Nat256.Sub(z, P, z); + } + } + + public static void AddExt(uint[] xx, uint[] yy, uint[] zz) + { + uint c = Nat256.AddExt(xx, yy, zz); + if (c != 0 || Nat256.GteExt(zz, PExt)) + { + Nat256.SubExt(zz, PExt, zz); + } + } + + public static void AddOne(uint[] x, uint[] z) + { + Array.Copy(x, 0, z, 0, 8); + uint c = Nat256.Inc(z, 0); + if (c != 0 || (z[7] == P7 && Nat256.Gte(z, P))) + { + Nat256.Sub(z, P, z); + } + } + + public static uint[] FromBigInteger(BigInteger x) + { + uint[] z = Nat256.FromBigInteger(x); + if (z[7] == P7 && Nat256.Gte(z, P)) + { + Nat256.Sub(z, P, z); + } + return z; + } + + public static void Half(uint[] x, uint[] z) + { + if ((x[0] & 1) == 0) + { + Nat256.ShiftDownBit(x, 0, z); + } + else + { + uint c = Nat256.Add(x, P, z); + Nat256.ShiftDownBit(z, c, z); + } + } + + public static void Multiply(uint[] x, uint[] y, uint[] z) + { + uint[] tt = Nat256.CreateExt(); + Nat256.Mul(x, y, tt); + Reduce(tt, z); + } + + public static void Negate(uint[] x, uint[] z) + { + if (Nat256.IsZero(x)) + { + Nat256.Zero(z); + } + else + { + Nat256.Sub(P, x, z); + } + } + + public static void Reduce(uint[] tt, uint[] z) + { + long t08 = tt[8], t09 = tt[9], t10 = tt[10], t11 = tt[11]; + long t12 = tt[12], t13 = tt[13], t14 = tt[14], t15 = tt[15]; + + long cc = 0; + cc += (long)tt[0] + t08 + t09 - t11 - t12 - t13 - t14; + z[0] = (uint)cc; + cc >>= 32; + cc += (long)tt[1] + t09 + t10 - t12 - t13 - t14 - t15; + z[1] = (uint)cc; + cc >>= 32; + cc += (long)tt[2] + t10 + t11 - t13 - t14 - t15; + z[2] = (uint)cc; + cc >>= 32; + cc += (long)tt[3] + ((t11 + t12) << 1) + t13 - t15 - t08 - t09; + z[3] = (uint)cc; + cc >>= 32; + cc += (long)tt[4] + ((t12 + t13) << 1) + t14 - t09 - t10; + z[4] = (uint)cc; + cc >>= 32; + cc += (long)tt[5] + ((t13 + t14) << 1) + t15 - t10 - t11; + z[5] = (uint)cc; + cc >>= 32; + cc += (long)tt[6] + ((t14 + t15) << 1) + t14 + t13 - t08 - t09; + z[6] = (uint)cc; + cc >>= 32; + cc += (long)tt[7] + (t15 << 1) + t15 + t08 - t10 - t11 - t12 - t13; + z[7] = (uint)cc; + cc >>= 32; + + int c = (int)cc; + if (c > 0) + { + do + { + c += Nat256.Sub(z, P, z); + } + while (c != 0); + + if (z[7] == P7 && Nat256.Gte(z, P)) + { + Nat256.Sub(z, P, z); + } + } + else if (c < 0) + { + do + { + c += (int)Nat256.Add(z, P, z); + } + while (c != 0); + } + } + + public static void Square(uint[] x, uint[] z) + { + uint[] tt = Nat256.CreateExt(); + Nat256.Square(x, tt); + Reduce(tt, z); + } + + public static void Subtract(uint[] x, uint[] y, uint[] z) + { + int c = Nat256.Sub(x, y, z); + if (c != 0) + { + Nat256.Add(z, P, z); + } + } + + public static void SubtractExt(uint[] xx, uint[] yy, uint[] zz) + { + int c = Nat256.SubExt(xx, yy, zz); + if (c != 0) + { + Nat256.AddExt(zz, PExt, zz); + } + } + + public static void Twice(uint[] x, uint[] z) + { + uint c = Nat256.ShiftUpBit(x, 0, z); + if (c != 0 || (z[7] == P7 && Nat256.Gte(z, P))) + { + Nat256.Sub(z, P, z); + } + } + } +} |