1 files changed, 16 insertions, 1 deletions
diff --git a/crypto/src/math/raw/Mod.cs b/crypto/src/math/raw/Mod.cs
index ea61bdd83..acbb1d91f 100644
--- a/crypto/src/math/raw/Mod.cs
+++ b/crypto/src/math/raw/Mod.cs
@@ -41,7 +41,7 @@ namespace Org.BouncyCastle.Math.Raw
public static uint Inverse32(uint d)
{
- Debug.Assert((d & 1) == 1);
+ Debug.Assert((d & 1U) == 1U);
//int x = d + (((d + 1) & 4) << 1); // d.x == 1 mod 2**4
uint x = d; // d.x == 1 mod 2**3
@@ -53,6 +53,21 @@ namespace Org.BouncyCastle.Math.Raw
return x;
}
+ public static ulong Inverse64(ulong d)
+ {
+ Debug.Assert((d & 1UL) == 1UL);
+
+ //ulong x = d + (((d + 1) & 4) << 1); // d.x == 1 mod 2**4
+ ulong x = d; // d.x == 1 mod 2**3
+ x *= 2 - d * x; // d.x == 1 mod 2**6
+ x *= 2 - d * x; // d.x == 1 mod 2**12
+ x *= 2 - d * x; // d.x == 1 mod 2**24
+ x *= 2 - d * x; // d.x == 1 mod 2**48
+ x *= 2 - d * x; // d.x == 1 mod 2**96
+ Debug.Assert(d * x == 1UL);
+ return x;
+ }
+
public static uint ModOddInverse(uint[] m, uint[] x, uint[] z)
{
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
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