Labels　based　on　physical　unclonable　functions　(PUFs)　have　been　proven　to　be　some　of　the　most　effective　anticounterfeiting　strategies.　However,　it　is　still　challenging　to　develop　PUF-based　anticounterfeiting　labels　with　low　prices,　simple　manufacturing,　and　easy　authentication.　Herein,　photochromic　PUF　labels　are　fabricated　by　randomly　dispersing　highly　crystalline　carbon　nitride　(HCCN)　particles　in　poly(vinyl　acetate)　(PVAc).　The　color　of　the　PVAc/HCCN　films　originating　from　photochromism　is　used　as　the　first　layer　of　safety,　which　is　verified　by　the　naked　eye.　The　pattern　of　the　randomly　distributed　HCCN　particles　within　the　photochromic　area　(i.e.,　the　PUF)　is　used　as　the　second　layer　of　security.　The　PUF　can　be　read　out　by　any　smartphone　equipped　with　a　portable　objective　and　then　automatically　authenticated　by　computer　vision　technology.　We　further　prove　the　accurate　and　feasible　authentication　of　the　prepared　PUFs　and　their　application　potentials.