diff --git a/DotBased.AspNet.Authority/Attributes/ProtectAttribute.cs b/DotBased.AspNet.Authority/Attributes/ProtectAttribute.cs
index 13394b8..58775b1 100644
--- a/DotBased.AspNet.Authority/Attributes/ProtectAttribute.cs
+++ b/DotBased.AspNet.Authority/Attributes/ProtectAttribute.cs
@@ -1,7 +1,7 @@
 namespace DotBased.AspNet.Authority.Attributes;
 
 /// <summary>
-/// Indicates that the property should be protected.
+/// Indicates to protect the property before saving to the repository.
 /// </summary>
 [AttributeUsage(AttributeTargets.Property)]
 public class ProtectAttribute : Attribute
diff --git a/DotBased.AspNet.Authority/DotBased.AspNet.Authority.csproj b/DotBased.AspNet.Authority/DotBased.AspNet.Authority.csproj
index 14ddfd0..b99e760 100644
--- a/DotBased.AspNet.Authority/DotBased.AspNet.Authority.csproj
+++ b/DotBased.AspNet.Authority/DotBased.AspNet.Authority.csproj
@@ -19,7 +19,6 @@
     <ItemGroup>
       <Folder Include="Authentication\" />
       <Folder Include="Models\Security\" />
-      <Folder Include="Repositories\" />
     </ItemGroup>
 
 </Project>
diff --git a/DotBased.AspNet.Authority/Interfaces/ISecurityVersionRepository.cs b/DotBased.AspNet.Authority/Interfaces/ISecurityVersionRepository.cs
new file mode 100644
index 0000000..866d22c
--- /dev/null
+++ b/DotBased.AspNet.Authority/Interfaces/ISecurityVersionRepository.cs
@@ -0,0 +1,7 @@
+namespace DotBased.AspNet.Authority.Interfaces;
+
+public interface ISecurityVersionRepository<in TRepositoryObject>
+{
+    public Task<long> GetSecurityVersionAsync(TRepositoryObject obj);
+    
+}
\ No newline at end of file
diff --git a/DotBased.AspNet.Authority/Interfaces/IUserRepository.cs b/DotBased.AspNet.Authority/Interfaces/IUserRepository.cs
index 0bc7ad3..c7035a3 100644
--- a/DotBased.AspNet.Authority/Interfaces/IUserRepository.cs
+++ b/DotBased.AspNet.Authority/Interfaces/IUserRepository.cs
@@ -1,6 +1,8 @@
 namespace DotBased.AspNet.Authority.Interfaces;
 
-public interface IUserRepository
+public interface IUserRepository<TUser, TId> : IVersionRepository<TUser>, ISecurityVersionRepository<TUser> where TUser : class where TId : IEquatable<TId>
 {
-    
+    public Task<TUser?> GetUserByIdAsync(TId id);
+
+    public Task<TId> GetUserIdAsync(TUser user);
 }
\ No newline at end of file
diff --git a/DotBased.AspNet.Authority/Interfaces/IVersionRepository.cs b/DotBased.AspNet.Authority/Interfaces/IVersionRepository.cs
new file mode 100644
index 0000000..b88ec89
--- /dev/null
+++ b/DotBased.AspNet.Authority/Interfaces/IVersionRepository.cs
@@ -0,0 +1,6 @@
+namespace DotBased.AspNet.Authority.Interfaces;
+
+public interface IVersionRepository<in TRepositoryObject>
+{
+    public Task<long> GetVersionAsync(TRepositoryObject obj);
+}
\ No newline at end of file
diff --git a/DotBased.AspNet.Authority/Models/Authority/AuthorityAttribute.cs b/DotBased.AspNet.Authority/Models/Authority/AuthorityAttribute.cs
new file mode 100644
index 0000000..dc4e5b5
--- /dev/null
+++ b/DotBased.AspNet.Authority/Models/Authority/AuthorityAttribute.cs
@@ -0,0 +1,25 @@
+namespace DotBased.AspNet.Authority.Models.Authority;
+
+public class AuthorityAttribute
+{
+    public AuthorityAttribute(string attributeKey, string bound) : this()
+    {
+        AttributeKey = attributeKey;
+        BoundId = bound;
+    }
+
+    public AuthorityAttribute()
+    {
+        
+    }
+
+    public string AttributeKey { get; set; } // ClaimType/Authority.attribute.enabled
+    
+    public string BoundId { get; set; } // Bound to User, Group, Role id
+
+    public string? AttributeValue { get; set; }
+    
+    public string? Type { get; set; } // AspNet.Claim.Role/Property/Data.JSON, Data.Raw, Data.Base64 etc.
+
+    public long Version { get; set; }
+}
\ No newline at end of file
diff --git a/DotBased.AspNet.Authority/Models/Authority/AuthorityGroup.cs b/DotBased.AspNet.Authority/Models/Authority/AuthorityGroup.cs
new file mode 100644
index 0000000..df010e8
--- /dev/null
+++ b/DotBased.AspNet.Authority/Models/Authority/AuthorityGroup.cs
@@ -0,0 +1,26 @@
+namespace DotBased.AspNet.Authority.Models.Authority;
+
+public class AuthorityGroup : AuthorityGroup<Guid>
+{
+    public AuthorityGroup(string name) : this()
+    {
+        Name = name;
+    }
+    
+    public AuthorityGroup()
+    {
+        Id = Guid.NewGuid();
+        CreatedDate = DateTime.Now;
+    }
+}
+
+public abstract class AuthorityGroup<TKey> where TKey : IEquatable<TKey>
+{
+    public TKey Id { get; set; }
+    
+    public string? Name { get; set; }
+
+    public long Version { get; set; }
+    
+    public DateTime CreatedDate { get; set; }
+}
\ No newline at end of file
diff --git a/DotBased.AspNet.Authority/Models/Authority/AuthorityRole.cs b/DotBased.AspNet.Authority/Models/Authority/AuthorityRole.cs
new file mode 100644
index 0000000..90ccee5
--- /dev/null
+++ b/DotBased.AspNet.Authority/Models/Authority/AuthorityRole.cs
@@ -0,0 +1,28 @@
+namespace DotBased.AspNet.Authority.Models.Authority;
+
+public class AuthorityRole : AuthorityRole<Guid>
+{
+    public AuthorityRole(string name) : this()
+    {
+        Name = name;
+    }
+    
+    public AuthorityRole()
+    {
+        Id = Guid.NewGuid();
+        CreatedDate = DateTime.Now;
+    }
+}
+
+public abstract class AuthorityRole<TKey> where TKey : IEquatable<TKey>
+{
+    public TKey Id { get; set; }
+    
+    public string? Name { get; set; }
+
+    public long Version { get; set; }
+
+    public DateTime CreatedDate { get; set; }
+
+    public override string ToString() => Name ?? string.Empty;
+}
\ No newline at end of file
diff --git a/DotBased.AspNet.Authority/Models/Authority/AuthorityUser.cs b/DotBased.AspNet.Authority/Models/Authority/AuthorityUser.cs
index 6c4f8a5..7ed6f9b 100644
--- a/DotBased.AspNet.Authority/Models/Authority/AuthorityUser.cs
+++ b/DotBased.AspNet.Authority/Models/Authority/AuthorityUser.cs
@@ -1,10 +1,52 @@
+using DotBased.AspNet.Authority.Attributes;
+
 namespace DotBased.AspNet.Authority.Models.Authority;
 
-public class AuthorityUser : AuthorityUserBase<Guid>
+public class AuthorityUser : AuthorityUser<Guid>
 {
+    public AuthorityUser(string userName) : this()
+    {
+        UserName = userName;
+    }
+    
     public AuthorityUser()
     {
         Id = Guid.NewGuid();
         CreatedDate = DateTime.Now;
     }
+}
+
+public abstract class AuthorityUser<TKey> where TKey : IEquatable<TKey>
+{
+    public TKey Id { get; set; }
+    
+    public bool Enabled { get; set; }
+    
+    public bool Locked { get; set; }
+
+    public DateTime LockedDate { get; set; }
+
+    public string? UserName { get; set; }
+
+    public string? PasswordHash { get; set; }
+    
+    public DateTime CreatedDate { get; set; }
+
+    public bool TwoFactorEnabled { get; set; }
+
+    public long Version { get; set; }
+
+    public long SecurityVersion { get; set; }
+    
+    [Protect]
+    public string? EmailAddress { get; set; }
+
+    public bool EmailConfirmed { get; set; }
+
+    [Protect]
+    public string? PhoneNumber { get; set; }
+
+    public bool PhoneNumberConfirmed { get; set; }
+
+    public override string ToString() => UserName ?? EmailAddress ?? string.Empty;
 }
\ No newline at end of file
diff --git a/DotBased.AspNet.Authority/Models/Authority/AuthorityUserBase.cs b/DotBased.AspNet.Authority/Models/Authority/AuthorityUserBase.cs
deleted file mode 100644
index 83b8166..0000000
--- a/DotBased.AspNet.Authority/Models/Authority/AuthorityUserBase.cs
+++ /dev/null
@@ -1,35 +0,0 @@
-using DotBased.AspNet.Authority.Attributes;
-
-namespace DotBased.AspNet.Authority.Models.Authority;
-
-public abstract class AuthorityUserBase<TKey> where TKey : IEquatable<TKey>
-{
-    public TKey Id { get; set; }
-    
-    public bool Enabled { get; set; }
-    
-    public bool Locked { get; set; }
-
-    public string UserName { get; set; }
-
-    public string PasswordHash { get; set; }
-    
-    public DateTime CreatedDate { get; set; }
-
-    public bool TwoFactorEnabled { get; set; }
-
-    public string ConcurrencyStamp { get; set; }
-    public string SecurityStamp { get; set; }
-    
-    
-    [Protect]
-    public string EmailAddress { get; set; }
-
-    public bool EmailConfirmed { get; set; }
-
-    [Protect]
-    public string PhoneNumber { get; set; }
-
-    public bool PhoneNumberConfirmed { get; set; }
-    
-}
\ No newline at end of file
diff --git a/DotBased.AspNet.Authority/Repositories/AuthorityRepository.cs b/DotBased.AspNet.Authority/Repositories/AuthorityRepository.cs
new file mode 100644
index 0000000..239c114
--- /dev/null
+++ b/DotBased.AspNet.Authority/Repositories/AuthorityRepository.cs
@@ -0,0 +1,6 @@
+namespace DotBased.AspNet.Authority.Repositories;
+
+public class AuthorityRepository // Inherit the repository interfaces?
+{
+    
+}
\ No newline at end of file
diff --git a/DotBased.AspNet.Authority/Services/AuthorityService.cs b/DotBased.AspNet.Authority/Services/AuthorityService.cs
index 9f90f61..2c61b55 100644
--- a/DotBased.AspNet.Authority/Services/AuthorityService.cs
+++ b/DotBased.AspNet.Authority/Services/AuthorityService.cs
@@ -2,5 +2,5 @@ namespace DotBased.AspNet.Authority.Services;
 
 public class AuthorityService
 {
-    
+    public long GenerateVersion() => DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
 }
\ No newline at end of file