Many a times, i’ve seen in MSDN Forums where people asking for the much granular-level of list security like who can read the list items and who can write/update t sayihe list items. There are couple of properties called ReadSecurity and Write Security in the SPListClass, that provides the more granular level of security.
The ReadSecurity property of the SPList gets or sets the Read security setting for the list. It can have the possible values of 1 or 2.
1- indicates all users can read the list items
2 – indicates the users can read the items only that they create
The WriteSecurity property of the SPList gets or sets the Read security setting for the list. It can have the possible values of 1, 2 and 4.
1 – Indicates that all the users can modify the all the items
2- Indicates the users can modify the items that they create
4 – Users cannot modify any list item