Adds Argon2 for password protection (#123)

Projects/Argon2/HashMetadata.cs

@@ -0,0 +1,60 @@
+using System;
+
+namespace Server.Accounting.Security
+{
+  /// <summary>
+  /// HashMetadata represents the information stored in the encoded Argon2 format
+  /// </summary>
+  public class HashMetadata
+  {
+    /// <summary>
+    /// The type of Argon2 hashing algorithm to use
+    /// Argon2d - The memory access is dependent upon the hash value (vulnerable to side-channel attacks)
+    /// Argon2i - The memory access is independent upon the hash value (safe from side-channel atacks)
+    /// </summary>
+    public Argon2Type ArgonType { get; set; }
+
+    /// <summary>
+    /// How much memory to use while hashing in kibibytes (KiB)
+    /// </summary>
+    public uint MemoryCost { get; set; }
+
+    /// <summary>
+    /// How many iterations of the Argon2 hash to perform
+    /// </summary>
+    public uint TimeCost { get; set; }
+
+    /// <summary>
+    /// How many threads to use while hashing
+    /// </summary>
+    public uint Parallelism { get; set; }
+
+    /// <summary>
+    /// The raw bytes of the salt
+    /// </summary>
+    public byte[] Salt { get; set; }
+
+    /// <summary>
+    /// The raw bytes of the hash
+    /// </summary>
+    public byte[] Hash { get; set; }
+
+
+    /// <summary>
+    /// A base-64 encoded string of the salt, minus the padding (=) characters
+    /// </summary>
+    public string GetBase64Salt() => Convert.ToBase64String(Salt).Replace("=", "");
+
+    /// <summary>
+    /// A base-64 encoded string of the hash, minus the padding (=) characters
+    /// </summary>
+    public string GetBase64Hash() => Convert.ToBase64String(Hash).Replace("=", "");
+
+
+    /// <summary>
+    /// Converts HashMetadata back into the original Argon2 formatted string.
+    /// </summary>
+    public override string ToString() =>
+      $"$argon2{(ArgonType == Argon2Type.Argon2i ? "i" : "d")}$v=19$m={MemoryCost},t={TimeCost},p={Parallelism}${GetBase64Salt()}${GetBase64Hash()}";
+  }
+}