Adding authentication and authorization flow

MainProject/Utils/CryptoUtils.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Security.Cryptography;
+using System.Text;
+using BasicDotnetTemplate.MainProject.Models.Settings;
+
+namespace BasicDotnetTemplate.MainProject.Utils;
+public class CryptUtils
+{
+    private readonly string secretKey;
+    private const int M = 16;
+    private const int N = 32;
+    private readonly NLog.Logger Logger = NLog.LogManager.GetCurrentClassLogger();
+    public CryptUtils(AppSettings appSettings)
+    {
+        secretKey = appSettings.EncryptionSettings?.Salt ?? String.Empty;
+    }
+
+    public string Decrypt(string encryptedData)
+    {
+        var decrypted = String.Empty;
+
+        if (String.IsNullOrEmpty(this.secretKey) || this.secretKey.Length < M)
+        {
+            throw new ArgumentException("Unable to proceed with decryption due to invalid settings");
+        }
+
+        if (!String.IsNullOrEmpty(encryptedData) && encryptedData.Length > N)
+        {
+            var iv = encryptedData.Substring(0, M);
+
+            var cipherText = encryptedData.Substring(N);
+            var fullCipher = Convert.FromBase64String(cipherText);
+
+            using (var aes = Aes.Create())
+            {
+                aes.Key = Encoding.UTF8.GetBytes(this.secretKey);
+                aes.IV = Encoding.UTF8.GetBytes(iv);
+
+                using (var decryptor = aes.CreateDecryptor(aes.Key, aes.IV))
+                {
+                    using (var msDecrypt = new MemoryStream(fullCipher))
+                    {
+                        using (var cryptoStream = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
+                        {
+                            using (var srDecrypt = new StreamReader(cryptoStream))
+                            {
+                                decrypted = srDecrypt.ReadToEnd();
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        return decrypted;
+    }
+
+}
+