copy one list to other list with permissions in sharepoint

 The below code copies entire source  list item including your permissions to  target list

public static SPListItem CopyItem(SPListItem sourceItem, string destinationListName)
{
//copy sourceItem to destinationList
SPList destinationList = sourceItem.Web.Lists[destinationListName];
SPListItem targetItem = destinationList.Items.Add();
foreach (SPField f in sourceItem.Fields)
{
if (!f.ReadOnlyField && f.InternalName != "Attachments")
{
targetItem[f.InternalName] = sourceItem[f.InternalName];
}
}
//copy attachments
foreach (string fileName in sourceItem.Attachments)
{
SPFile file = sourceItem.ParentList.ParentWeb.GetFile(sourceItem.Attachments.UrlPrefix + fileName);
byte[] imageData = file.OpenBinary();
targetItem.Attachments.Add(fileName, imageData);
}
targetItem.SystemUpdate(false);
//Break the permissions inheritance from parent
targetItem.BreakRoleInheritance(false);
//removing permissions
while (targetItem.RoleAssignments.Count > 0)
{
targetItem.RoleAssignments.Remove(0);
}
//copying the permission set from source item
foreach (SPRoleAssignment role in sourceItem.RoleAssignments)
{
targetItem.RoleAssignments.Add(role);
}
targetItem.SystemUpdate(false);
return targetItem;
}