Add support for changing kSecUseDataProtectionKeychain

Rename variables and functions to match Apple

keychain.go

@@ -190,6 +190,23 @@ var syncTypeRef = map[Synchronizable]C.CFTypeRef{
 	SynchronizableNo:  C.CFTypeRef(C.kCFBooleanFalse),
 }
 
+// DataProtection is the items data protection status
+type UseDataProtectionKeychain int
+
+const (
+	// UseDataProtectionKeychainYes enables data protection mode
+	UseDataProtectionKeychainYes = 1
+	// UseDataProtectionKeychainNo disables data protection mode
+	UseDataProtectionKeychainNo = 2
+)
+
+// DataProtectionKey is the key type for DataProtection
+var UseDataProtectionKey = attrKey(C.CFTypeRef(C.kSecUseDataProtectionKeychain))
+var dataProtectionTypeRef = map[UseDataProtectionKeychain]C.CFTypeRef{
+	UseDataProtectionKeychainYes: C.CFTypeRef(C.kCFBooleanTrue),
+	UseDataProtectionKeychainNo:  C.CFTypeRef(C.kCFBooleanFalse),
+}
+
 // Accessible is the items accessibility
 type Accessible int
 
@@ -303,6 +320,11 @@ func (k *Item) SetSynchronizable(sync Synchronizable) {
 	}
 }
 
+// SetSynchronizable sets the synchronizable attribute
+func (k *Item) SetUseDataProtectionKeychain(dataProtection UseDataProtectionKeychain) {
+	k.attr[UseDataProtectionKey] = dataProtectionTypeRef[dataProtection]
+}
+
 // SetAccessible sets the accessible attribute
 func (k *Item) SetAccessible(accessible Accessible) {
 	if accessible != AccessibleDefault {