 okay today I'm going to demonstrate to you the digital signature features of SD25 tags as you can see these two tags looks almost identical from the outside you can't tell which one is which and if you take a phone and you tap on one it would take you to www.st.com right now if I tap the other tag it also took me to www.st.com although they share the same URL these two tags actually have special signatures on them only one of these tag has a signature that prove to this reader which is consisting of an SCM32F41RE nuclear board and the SC25R3911B transceiver board this reader is an embedded reader so in a way you can think of it as if it was embedded in a door for hotel or any sort of application that allows some kind of NFC authentication or NFC access for example if I tap this tag it shows me that this is a tag but it doesn't do anything more than linking this LED identifying the tag itself if I tap this tag notice that the different light patterns it means that this reader has a certain kind of code firmware I would say that basically identify and authenticate the signature store on this tag although this tag look the same as that start storing the same content this one actually has a special signature so it'll be very difficult to clone this tag particularly this tag is not doesn't have any special signature as you can see this tag has a special signature so when you look at application like this you can actually use it for something that basically like a brand protection application when you can embed a tag with a special signature so that you can distinguish from the articles of product that has been cloned all right thank you