commit 836ca442c7cd259471aedccbe542dccc53c5602e
Author: AJ <ajisaacs@rogersengineering.net>
Date:   Thu Jan 7 06:39:45 2021 -0500

    Initial commit

diff --git a/PasswordHash.cs b/PasswordHash.cs
new file mode 100644
index 0000000..89e4632
--- /dev/null
+++ b/PasswordHash.cs
@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace WindowsAppWithLogin1
+{
+    public class PasswordHash
+    {
+        public const int SaltByteSize = 24;
+        public const int HashByteSize = 20; // to match the size of the PBKDF2-HMAC-SHA-1 hash 
+        public const int Pbkdf2Iterations = 1000;
+        public const int IterationIndex = 0;
+        public const int SaltIndex = 1;
+        public const int Pbkdf2Index = 2;
+
+        public static string HashPassword(string password)
+        {
+            var cryptoProvider = new RNGCryptoServiceProvider();
+            byte[] salt = new byte[SaltByteSize];
+            cryptoProvider.GetBytes(salt);
+
+            var hash = GetPbkdf2Bytes(password, salt, Pbkdf2Iterations, HashByteSize);
+            return Pbkdf2Iterations + ":" +
+                   Convert.ToBase64String(salt) + ":" +
+                   Convert.ToBase64String(hash);
+        }
+
+        public static bool ValidatePassword(string password, string correctHash)
+        {
+            char[] delimiter = { ':' };
+            var split = correctHash.Split(delimiter);
+            var iterations = Int32.Parse(split[IterationIndex]);
+            var salt = Convert.FromBase64String(split[SaltIndex]);
+            var hash = Convert.FromBase64String(split[Pbkdf2Index]);
+
+            var testHash = GetPbkdf2Bytes(password, salt, iterations, hash.Length);
+            return SlowEquals(hash, testHash);
+        }
+
+        private static bool SlowEquals(byte[] a, byte[] b)
+        {
+            var diff = (uint)a.Length ^ (uint)b.Length;
+            for (int i = 0; i < a.Length && i < b.Length; i++)
+            {
+                diff |= (uint)(a[i] ^ b[i]);
+            }
+            return diff == 0;
+        }
+
+        private static byte[] GetPbkdf2Bytes(string password, byte[] salt, int iterations, int outputBytes)
+        {
+            var pbkdf2 = new Rfc2898DeriveBytes(password, salt);
+            pbkdf2.IterationCount = iterations;
+            return pbkdf2.GetBytes(outputBytes);
+        }
+    }
+}