diff --git a/SurveyBackend/SurveyBackend.API/Program.cs b/SurveyBackend/SurveyBackend.API/Program.cs
index 77e7695..d56c7ab 100644
--- a/SurveyBackend/SurveyBackend.API/Program.cs
+++ b/SurveyBackend/SurveyBackend.API/Program.cs
@@ -37,7 +37,7 @@ public class Program
 
         builder.Services.AddScoped<IPasswordHasher, Sha256PasswordHasher>();
 
-        builder.Services.AddScoped<AuthorizationService>();
+        builder.Services.AddScoped<IAuthorizationService, AuthorizationService>();
 
         builder.Services.AddScoped<ISurveyRepository, SurveyRepository>();
         builder.Services.AddScoped<ISurveyService, SurveyService>();
diff --git a/SurveyBackend/SurveyBackend.Core/Services/IAuthorizationService.cs b/SurveyBackend/SurveyBackend.Core/Services/IAuthorizationService.cs
new file mode 100644
index 0000000..1767ce2
--- /dev/null
+++ b/SurveyBackend/SurveyBackend.Core/Services/IAuthorizationService.cs
@@ -0,0 +1,9 @@
+using SurveyBackend.Core.Models;
+
+namespace SurveyBackend.Core.Services;
+
+public interface IAuthorizationService
+{
+    public Task<string?> LogInUser(string email, string password);
+    public Task RegisterUser(User user);
+}
\ No newline at end of file
diff --git a/SurveyBackend/SurveyBackend.Services/Services/AuthorizationService.cs b/SurveyBackend/SurveyBackend.Services/Services/AuthorizationService.cs
index 25fcbdf..0e9907f 100644
--- a/SurveyBackend/SurveyBackend.Services/Services/AuthorizationService.cs
+++ b/SurveyBackend/SurveyBackend.Services/Services/AuthorizationService.cs
@@ -4,7 +4,7 @@ using SurveyBackend.Services.Helpers;
 
 namespace SurveyBackend.Services.Services;
 
-public class AuthorizationService
+public class AuthorizationService : IAuthorizationService
 {
     private readonly IUserService _userService;
     private readonly IPasswordHasher _passwordHasher;