diff --git a/crypto/src/math/ec/rfc7748/X448.cs b/crypto/src/math/ec/rfc7748/X448.cs
index 32a4a9e2a..8ded25a06 100644
--- a/crypto/src/math/ec/rfc7748/X448.cs
+++ b/crypto/src/math/ec/rfc7748/X448.cs
@@ -58,67 +58,72 @@ namespace Org.BouncyCastle.Math.EC.Rfc7748
X448Field.Mul(z, A, z);
}
- [MethodImpl(MethodImplOptions.Synchronized)]
+ // https://stackoverflow.com/questions/2223656/what-does-methodimploptions-synchronized-do
+ // Not available in lower .net standard versions
+ //[MethodImpl(MethodImplOptions.Synchronized)]
public static void Precompute()
{
- if (precompBase != null)
- return;
+ lock (typeof(X448))
+ {
+ if (precompBase != null)
+ return;
- precompBase = new uint[X448Field.Size * 446];
+ precompBase = new uint[X448Field.Size * 446];
- uint[] xs = precompBase;
- uint[] zs = new uint[X448Field.Size * 445];
+ uint[] xs = precompBase;
+ uint[] zs = new uint[X448Field.Size * 445];
- uint[] x = X448Field.Create(); x[0] = 5;
- uint[] z = X448Field.Create(); z[0] = 1;
+ uint[] x = X448Field.Create(); x[0] = 5;
+ uint[] z = X448Field.Create(); z[0] = 1;
- uint[] n = X448Field.Create();
- uint[] d = X448Field.Create();
+ uint[] n = X448Field.Create();
+ uint[] d = X448Field.Create();
- //X448Field.Apm(x, z, n, d);
- X448Field.Add(x, z, n);
- X448Field.Sub(x, z, d);
+ //X448Field.Apm(x, z, n, d);
+ X448Field.Add(x, z, n);
+ X448Field.Sub(x, z, d);
- uint[] c = X448Field.Create(); X448Field.Copy(d, 0, c, 0);
+ uint[] c = X448Field.Create(); X448Field.Copy(d, 0, c, 0);
- int off = 0;
- for (;;)
- {
- X448Field.Copy(n, 0, xs, off);
+ int off = 0;
+ for (; ; )
+ {
+ X448Field.Copy(n, 0, xs, off);
- if (off == (X448Field.Size * 445))
- break;
+ if (off == (X448Field.Size * 445))
+ break;
- PointDouble(x, z);
+ PointDouble(x, z);
- //X448Field.Apm(x, z, n, d);
- X448Field.Add(x, z, n);
- X448Field.Sub(x, z, d);
- X448Field.Mul(n, c, n);
- X448Field.Mul(c, d, c);
+ //X448Field.Apm(x, z, n, d);
+ X448Field.Add(x, z, n);
+ X448Field.Sub(x, z, d);
+ X448Field.Mul(n, c, n);
+ X448Field.Mul(c, d, c);
- X448Field.Copy(d, 0, zs, off);
+ X448Field.Copy(d, 0, zs, off);
- off += X448Field.Size;
- }
+ off += X448Field.Size;
+ }
- uint[] u = X448Field.Create();
- X448Field.Inv(c, u);
+ uint[] u = X448Field.Create();
+ X448Field.Inv(c, u);
- for (;;)
- {
- X448Field.Copy(xs, off, x, 0);
+ for (; ; )
+ {
+ X448Field.Copy(xs, off, x, 0);
- X448Field.Mul(x, u, x);
- //X448Field.Normalize(x);
- X448Field.Copy(x, 0, precompBase, off);
+ X448Field.Mul(x, u, x);
+ //X448Field.Normalize(x);
+ X448Field.Copy(x, 0, precompBase, off);
- if (off == 0)
- break;
+ if (off == 0)
+ break;
- off -= X448Field.Size;
- X448Field.Copy(zs, off, z, 0);
- X448Field.Mul(u, z, u);
+ off -= X448Field.Size;
+ X448Field.Copy(zs, off, z, 0);
+ X448Field.Mul(u, z, u);
+ }
}
}
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