first real commit

License.cs

@@ -0,0 +1,86 @@
+/*
+ * Created by SharpDevelop.
+ * User: Doug.Macintosh
+ * Date: 2023-02-05
+ * Time: 9:52 AM
+ * 
+ * To change this template use Tools | Options | Coding | Edit Standard Headers.
+ */
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.IO.Compression;
+using System.Runtime.ConstrainedExecution;
+using System.Security.Cryptography;
+using System.Text;
+
+using Newtonsoft.Json;
+
+
+namespace cdrtool
+{
+    class License
+    {
+
+        public static string validate(string filename)
+        {
+            string license;
+            if ( (!File.Exists(filename)) || ( new FileInfo(filename).Length == 0))
+                throw new FileNotFoundException("License file missing or corrupt.");
+
+            if (cdrtool.company.Length < 6) 
+                throw new InvalidDataException("User account missing or corrupt.");
+
+            try
+            {
+                license = License.getLicense(filename, makeHash(cdrtool.company + cdrtool.product + cdrtool.version.Substring(0, 3)).Substring(0, 32));
+                Logger.Log(5, "Decrypted License Key: {0}", license);
+            }
+            catch (Exception)
+            {
+                throw new InvalidDataException("Unable to decrypt license file, please contact Support.");
+            }
+
+            return license;
+
+        }
+
+        private static string getLicense(string filename, string secretKey)
+        {
+            return Decrypt(File.ReadAllText(filename), secretKey);
+        }
+
+        private static string Decrypt(string encryptedText, string secretKey)
+        {
+            byte[] encryptedTextBytes = Convert.FromBase64String(encryptedText);
+            using (Aes aes = Aes.Create())
+            {
+                aes.Key = Encoding.UTF8.GetBytes(secretKey);
+                byte[] iv = new byte[aes.BlockSize / 8];
+                byte[] encrypted = new byte[encryptedTextBytes.Length - iv.Length];
+
+                Array.Copy(encryptedTextBytes, 0, iv, 0, iv.Length);
+                Array.Copy(encryptedTextBytes, iv.Length, encrypted, 0, encrypted.Length);
+
+                aes.IV = iv;
+
+                using (ICryptoTransform decryptor = aes.CreateDecryptor(aes.Key, aes.IV))
+                {
+                    byte[] decryptedBytes = decryptor.TransformFinalBlock(encrypted, 0, encrypted.Length);
+                    return Encoding.UTF8.GetString(decryptedBytes);
+                }
+            }
+        }
+
+        private static string makeHash(string InputString)
+        {
+            using (SHA256 sha256Hash = SHA256.Create())
+            {
+                byte[] bytes = sha256Hash.ComputeHash(System.Text.Encoding.UTF8.GetBytes(InputString));
+                return Convert.ToBase64String(bytes);
+            }
+        }
+
+
+    }
+}