diff --git a/Whitelist/contracts/white.clar b/Whitelist/contracts/white.clar
index 4cb935a..078a124 100644
--- a/Whitelist/contracts/white.clar
+++ b/Whitelist/contracts/white.clar
@@ -1,15 +1,66 @@
+;; Define constants
+(define-constant contract-owner tx-sender)
+(define-constant err-owner-only (err u100))
+(define-constant err-not-found (err u101))
+(define-constant err-invalid-expiration (err u102))
+(define-constant err-invalid-address (err u103))
+(define-constant minimum-expiration u1440)
 
-;; white
-;; <add a description here>
+;; Define data map for the whitelist
+(define-map whitelist
+  { addr: principal }
+  { expiration: uint,
+    active: bool })
 
-;; constants
-;;
+;; Private helper functions
+(define-private (is-valid-expiration-time (expiration-time uint))
+  (>= expiration-time (+ block-height minimum-expiration)))
 
-;; data maps and vars
-;;
+(define-private (is-valid-address (address principal))
+  (not (is-eq address contract-owner)))
 
-;; private functions
-;;
+(define-private (is-authorized)
+  (is-eq tx-sender contract-owner))
 
-;; public functions
-;;
+;; Read-only functions
+(define-read-only (is-whitelisted (address principal))
+  (match (map-get? whitelist { addr: address })
+    entry (ok (and (get active entry)
+                  (>= (get expiration entry) block-height)))
+    (ok false)))
+
+;; Public functions
+(define-public (add-to-whitelist (address principal) (expiration-time uint))
+  (begin
+    (asserts! (is-authorized) err-owner-only)
+    (asserts! (is-valid-address address) err-invalid-address)
+    (asserts! (is-valid-expiration-time expiration-time) err-invalid-expiration)
+    (ok (map-set whitelist
+        { addr: address }
+        { expiration: expiration-time,
+          active: true }))))
+
+(define-public (deactivate-whitelist-entry (address principal))
+  (begin
+    (asserts! (is-authorized) err-owner-only)
+    (asserts! (is-valid-address address) err-invalid-address)
+    (match (map-get? whitelist { addr: address })
+      entry
+      (ok (map-set whitelist
+        { addr: address }
+        { expiration: (get expiration entry),
+          active: false }))
+      err-not-found)))
+
+(define-public (update-expiration (address principal) (new-expiration uint))
+  (begin
+    (asserts! (is-authorized) err-owner-only)
+    (asserts! (is-valid-address address) err-invalid-address)
+    (asserts! (is-valid-expiration-time new-expiration) err-invalid-expiration)
+    (match (map-get? whitelist { addr: address })
+      entry
+      (ok (map-set whitelist
+        { addr: address }
+        { expiration: new-expiration,
+          active: (get active entry) }))
+      err-not-found)))
\ No newline at end of file