Since　security　is　the　most　important　issue　in　the　Internet　of　things　(IoT)　and　blockchain　(BC),　this　article　aims　to　identify,　analyze,　and　organize　the　literature　about　security　in　the　IoT　and　BC　context　up　to　August　2020　and　proposes　an　agenda　for　future　research.　The　39　related　articles　have　been　ranked　into　three　main　categories,　smart　city,　data　management　and　information,　and　architecture　and　framework.　The　findings　showed　that　the　distinctive　technical　aspects　of　BC　might　impressively　find　a　solution　for　privacy　and　security　problems　encountering　the　IoT　development,　supply　distributed　storage,　transparency,　trust,　and　other　support　for　IoT.　It　is　conducted　to　form　a　valid,　impressive,　and　secure　distributed　IoT　network　and　supply　a　beneficial　guarantee　for　the　security　of　IoT　users.　Since　the　devices　of　IoT　are　simply　reachable,　a　BC-depended　solution　can　be　executed,　which　may　certify　the　confidentiality　and　safety　of　the　info　preserved　in　the　devices.　In　addition,　BC　technology　facilitates　the　secure　sharing　of　IoT　datasets　and　secure　IoT　systems.　However,　blockchains　require　more　computational　strength　and　high　bandwidth　and　are　not　perfectly　proper　for　many　resource-restricted　IoT　devices.　©　2020　John　Wiley　&　Sons,　Ltd.