feat: add key storage Helper

Author: twsc-james

EccSDK/KeyStorageHelper.cs

@@ -0,0 +1,33 @@
+using System.Text.Json;
+using EccSDK.models;
+
+namespace EccSDK;
+
+public static class KeyStorageHelper
+{
+    private const string KeysPath = "~/keys.json";
+
+    public static KeyStorageData LoadKeyPair()
+    {
+        if (File.Exists(KeysPath))
+        {
+            return RestoreKeys();
+        }
+
+        var keyStorageData = new KeyStorageData
+        {
+            KeyPair = EccGenerator.GenerateKeyPair(256),
+            SessionKey = SessionKeyGenerator.GenerateSessionKey()
+        };
+
+        keyStorageData.SaveKeys(KeysPath);
+
+        return keyStorageData;
+    }
+
+    private static KeyStorageData RestoreKeys()
+    {
+        var keyData = File.ReadAllText(KeysPath);
+        return JsonSerializer.Deserialize<KeyStorageData>(keyData)!;
+    }
+}

EccSDK/models/KeyStorageData.cs

@@ -0,0 +1,15 @@
+using System.Text.Json;
+
+namespace EccSDK.models;
+
+public class KeyStorageData
+{
+    public KeyPair KeyPair { get; set; }
+    public SessionKey SessionKey { get; set; }
+
+    public void SaveKeys(string keyPath)
+    {
+        var keyWithJson = JsonSerializer.Serialize(this);
+        File.WriteAllText(keyPath, keyWithJson);
+    }
+}