added GetHash helper

Svrnty.GeoManagement.Abstractions/ServiceCollectionExtensions.cs

@@ -1,3 +1,5 @@
+using System.Security.Cryptography;
+using System.Text;
 using Svrnty.GeoManagement.Abstractions.Abstractions;
 using Svrnty.GeoManagement.Abstractions.Models;
 
@@ -65,4 +67,16 @@ public static class ServiceCollectionExtensions
 
     return $"{address.Line2}, {address.Line1}\n{address.City}, {address.Subdivision} {address.PostalCode}\n{address.CountryCode}";
   }
+
+  public static string GetHash(this IAddress address)
+    => ComputeSha256Hex(address.GetFormattedAddress());
+  
+  private static string ComputeSha256Hex(string input)
+  {
+    using SHA256 sha256 = SHA256.Create();
+    byte[] bytes = Encoding.UTF8.GetBytes(input);
+    byte[] hash = sha256.ComputeHash(bytes);
+
+    return Convert.ToHexString(hash).ToLower();
+  }
 }