Fixing user password generation/validation - wip

MainProject/Utils/CryptUtils.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Security.Cryptography;
+using System.Text;
+using BasicDotnetTemplate.MainProject.Models.Settings;
+
+namespace BasicDotnetTemplate.MainProject.Utils;
+public class CryptUtils(AppSettings appSettings)
+{
+    private readonly string _secret = appSettings.EncryptionSettings?.Secret ?? String.Empty;
+    private const int _M = 16;
+    private const int _N = 32;
+
+    public string Decrypt(string encryptedData)
+    {
+        var decrypted = String.Empty;
+
+        if (String.IsNullOrEmpty(this._secret) || this._secret.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._secret);
+                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;
+    }
+
+    public static string GeneratePepper()
+    {
+        using var rng = RandomNumberGenerator.Create();
+        var bytePepper = new byte[16];
+        rng.GetBytes(bytePepper);
+        var pepper = Convert.ToBase64String(bytePepper);
+        return pepper;
+    }
+
+    public static string GeneratePassword(string password, string salt, int iterations, string? pepper = "")
+    {
+        string hashedPassword = password;
+        for (var i = 0; i <= iterations; i++)
+        {
+            var passwordSaltPepper = $"{hashedPassword}{salt}{pepper}";
+            var byteValue = Encoding.UTF8.GetBytes(passwordSaltPepper);
+            var byteHash = SHA256.HashData(byteValue);
+            hashedPassword = Convert.ToBase64String(byteHash);
+        }
+
+        return hashedPassword;
+    }
+
+    public static bool VerifyPassword(string userPassword, string password, string salt, int iterations, string? pepper = "")
+    {
+        string hashedPassword = GeneratePassword(password, salt, iterations, pepper);
+        return hashedPassword.Equals(userPassword, StringComparison.OrdinalIgnoreCase);
+    }
+
+
+
+}
+