LMBQ-249: Adding GenerateRandomPassword helper

Lombiq.HelpfulLibraries.OrchardCore/Users/PasswordHelper.cs

@@ -0,0 +1,40 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+
+namespace Lombiq.HelpfulLibraries.OrchardCore.Users;
+
+public static class PasswordHelper
+{
+    /// <summary>
+    /// Generates a <paramref name="minLength"/> long random password.
+    /// </summary>
+    public static string GenerateRandomPassword(int minLength)
+    {
+        const string validChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*()_+-="; // #spell-check-ignore-line
+
+        using var rng = RandomNumberGenerator.Create();
+        const string digits = "0123456789";
+        const string lowerChars = "abcdefghijklmnopqrstuvwxyz"; // #spell-check-ignore-line
+        const string upperChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; // #spell-check-ignore-line
+        const string specialChars = "!@#$%^&*()_+-=";
+
+        var passwordChars = new List<char>
+            {
+                digits[rng.Next(0, digits.Length)],
+                lowerChars[rng.Next(0, lowerChars.Length)],
+                upperChars[rng.Next(0, upperChars.Length)],
+                specialChars[rng.Next(0, specialChars.Length)],
+            };
+
+        while (passwordChars.Count < minLength)
+        {
+            passwordChars.Add(validChars[rng.Next(0, validChars.Length)]);
+        }
+
+        passwordChars = passwordChars.OrderBy(c => rng.Next(0, int.MaxValue)).ToList();
+        string password = new(passwordChars.ToArray());
+
+        return password;
+    }
+}