diff --git a/crypto/src/math/ec/custom/sec/SecT283Field.cs b/crypto/src/math/ec/custom/sec/SecT283Field.cs
index 9afb27461..903ea02ff 100644
--- a/crypto/src/math/ec/custom/sec/SecT283Field.cs
+++ b/crypto/src/math/ec/custom/sec/SecT283Field.cs
@@ -48,6 +48,41 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
return z;
}
+ public static void Invert(ulong[] x, ulong[] z)
+ {
+ if (Nat320.IsZero64(x))
+ throw new InvalidOperationException();
+
+ // Itoh-Tsujii inversion
+
+ ulong[] t0 = Nat320.Create64();
+ ulong[] t1 = Nat320.Create64();
+
+ Square(x, t0);
+ Multiply(t0, x, t0);
+ SquareN(t0, 2, t1);
+ Multiply(t1, t0, t1);
+ SquareN(t1, 4, t0);
+ Multiply(t0, t1, t0);
+ SquareN(t0, 8, t1);
+ Multiply(t1, t0, t1);
+ Square(t1, t1);
+ Multiply(t1, x, t1);
+ SquareN(t1, 17, t0);
+ Multiply(t0, t1, t0);
+ Square(t0, t0);
+ Multiply(t0, x, t0);
+ SquareN(t0, 35, t1);
+ Multiply(t1, t0, t1);
+ SquareN(t1, 70, t0);
+ Multiply(t0, t1, t0);
+ Square(t0, t0);
+ Multiply(t0, x, t0);
+ SquareN(t0, 141, t1);
+ Multiply(t1, t0, t1);
+ Square(t1, z);
+ }
+
public static void Multiply(ulong[] x, ulong[] y, ulong[] z)
{
ulong[] tt = Nat320.CreateExt64();
@@ -292,7 +327,7 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
Debug.Assert(y >> 57 == 0);
ulong[] u = new ulong[8];
- // u[0] = 0;
+ //u[0] = 0;
u[1] = y;
u[2] = u[1] << 1;
u[3] = u[2] ^ y;
@@ -306,7 +341,7 @@ namespace Org.BouncyCastle.Math.EC.Custom.Sec
int k = 48;
do
{
- j = (uint)(x >> k);
+ j = (uint)(x >> k);
g = u[j & 7]
^ u[(j >> 3) & 7] << 3
^ u[(j >> 6) & 7] << 6;
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