Add a new modinv constant for field elements

Author: Coding-Enthusiast

Src/Autarkysoft.Bitcoin/Cryptography/EllipticCurve/ModInv32ModInfo.cs

@@ -16,11 +16,21 @@ public ModInv32ModInfo(in ModInv32Signed30 mod, uint modinv30)
         public readonly ModInv32Signed30 modulus;
         public readonly uint modulus_inv30;
 
-        private static readonly ModInv32ModInfo _const = new ModInv32ModInfo(
+        private static readonly ModInv32ModInfo _scConst = new ModInv32ModInfo(
             new ModInv32Signed30(0x10364141, 0x3F497A33, 0x348A03BB, 0x2BB739AB, -0x146, 0, 0, 0, 65536),
             0x2A774EC1U);
-        // secp256k1_const_modinfo_scalar
-        internal static ref readonly ModInv32ModInfo Constant => ref _const;
+        /// <summary>
+        /// secp256k1_const_modinfo_scalar
+        /// </summary>
+        internal static ref readonly ModInv32ModInfo ScalarConstant => ref _scConst;
+
+        private static readonly ModInv32ModInfo _feConst = new ModInv32ModInfo(
+            new ModInv32Signed30(-0x3D1, -4, 0, 0, 0, 0, 0, 0, 65536),
+            0x2DDACACF);
+        /// <summary>
+        /// secp256k1_const_modinfo_fe
+        /// </summary>
+        internal static ref readonly ModInv32ModInfo FeConstant => ref _feConst;
     }
 
     internal class ModInv32Trans2x2

Src/Autarkysoft.Bitcoin/Cryptography/EllipticCurve/Scalar8x32.cs

@@ -555,7 +555,7 @@ public Scalar8x32 Inverse()
 #endif
             ModInv32Signed30 s = new ModInv32Signed30(this);
             // secp256k1_modinv32(&s, &secp256k1_const_modinfo_scalar);
-            ModInv32.Compute(ref s, ModInv32ModInfo.Constant);
+            ModInv32.Compute(ref s, ModInv32ModInfo.ScalarConstant);
             Scalar8x32 r = s.ToScalar8x32();
 #if DEBUG
             Debug.Assert(r.Verify());
@@ -575,7 +575,7 @@ public Scalar8x32 InverseVar()
             bool zero_in = IsZero;
 #endif
             ModInv32Signed30 s = new ModInv32Signed30(this);
-            ModInv32.ComputeVar(ref s, ModInv32ModInfo.Constant);
+            ModInv32.ComputeVar(ref s, ModInv32ModInfo.ScalarConstant);
             Scalar8x32 r = s.ToScalar8x32();
 
 #if DEBUG