Use:
public void Post([Bind(Include = "ID,Name,UserName,....")] CreateUserRequest request)
{
if(ModelState.IsValid)
{
var response = _facade.CreateUser(request);
SaveUserDetailsToCookie(response.RavenUser.ID, response.RavenUser.UserName, EncryptionDecryption.DecryptString(response.RavenUser.Password));//Cookie should be stored Decrypted Format
HttpContext.Current.Session[SessionDataKey.UserId.ToString()] = response.RavenUser.ID.ToString();
HttpContext.Current.Session[SessionDataKey.UserName.ToString()] = response.RavenUser.UserName;
}
}