Moved PrivateKey to ApiCredentials, ApiCredentials use SecureString, Refactored array param string building

CryptoExchange.Net/Authentication/ApiCredentials.cs

@@ -1,27 +1,82 @@
 using System;
+using System.Security;
 
 namespace CryptoExchange.Net.Authentication
 {
-    public class ApiCredentials
+    public class ApiCredentials: IDisposable
     {
         /// <summary>
-        /// The api key
+        /// The api key to authenticate requests
         /// </summary>
-        public string Key { get; }
+        public SecureString Key { get; }
+
         /// <summary>
-        /// The api secret
+        /// The api secret to authenticate requests
         /// </summary>
-        public string Secret { get; }
+        public SecureString Secret { get; }
 
-        public ApiCredentials() { }
+        /// <summary>
+        /// The private key to authenticate requests
+        /// </summary>
+        public SecureString PrivateKey { get; }
 
-        public ApiCredentials(string key, string secret)
+        /// <summary>
+        /// Create Api credentials providing a private key for authenication
+        /// </summary>
+        /// <param name="privateKey">The private key used for signing</param>
+        public ApiCredentials(SecureString privateKey)
         {
-            if(string.IsNullOrEmpty(key) || string.IsNullOrEmpty(secret))
-                throw new ArgumentException("Apikey or apisecret not provided");
+            PrivateKey = Key;
+        }
 
+        /// <summary>
+        /// Create Api credentials providing a private key for authenication
+        /// </summary>
+        /// <param name="privateKey">The private key used for signing</param>
+        public ApiCredentials(string privateKey)
+        {
+            var securePrivateKey = new SecureString();
+            foreach (var c in privateKey)
+                securePrivateKey.AppendChar(c);
+            securePrivateKey.MakeReadOnly();
+            PrivateKey = securePrivateKey;
+        }
+
+        /// <summary>
+        /// Create Api credentials providing a api key and secret for authenciation
+        /// </summary>
+        /// <param name="key">The api key used for identification</param>
+        /// <param name="secret">The api secret used for signing</param>
+        public ApiCredentials(SecureString key, SecureString secret)
+        {
             Key = key;
             Secret = secret;
         }
+
+        /// <summary>
+        /// Create Api credentials providing a private key for authenication
+        /// </summary>
+        /// <param name="privateKey">The private key used for signing</param>
+        public ApiCredentials(string key, string secret)
+        {
+            var secureApiKey = new SecureString();
+            foreach (var c in key)
+                secureApiKey.AppendChar(c);
+            secureApiKey.MakeReadOnly();
+            Key = secureApiKey;
+
+            var secureApiSecret = new SecureString();
+            foreach (var c in secret)
+                secureApiSecret.AppendChar(c);
+            secureApiSecret.MakeReadOnly();
+            Secret = secureApiSecret;
+        }
+
+        public void Dispose()
+        {
+            Key?.Dispose();
+            Secret?.Dispose();
+            PrivateKey?.Dispose();
+        }
     }
 }