feat: extract SessionKeyGenerator

Author: twsc-james

EccSDK/SessionKeyGenerator.cs

@@ -0,0 +1,11 @@
+using Org.BouncyCastle.Math;
+
+namespace EccSDK;
+
+public class SessionKeyGenerator
+{
+    public static BigInteger GenerateSessionKey()
+    {
+        return new BigInteger(256, new Random());
+    }
+}