Hey Michael, Thank you very much for you elaborate answer. As you suggested, I did not distinguish between smart cards and NFC tags.
I have several follow-up questions regarding your answer. *Regarding P2P communication* - If I understand correctly, Android uses a proprietary protocol (which I believe is called com.android.npp) on top of LLCP as specified by the NFC Forum, which is a protocol on top of NFCIP-1 as specified in ISO 18092. I read in another discussion in this group about a spec on com.android.npp that's due to be published, is there any information as to a specific date for this publication? Or is there any other (documented) way for regular terminals or desktop readers to communicate with an Android phone over P2P? *Regarding Card Emulation* - How would installation of an application on the SE work? // How would permission be given, and to whom? I don't yet clearly see how this would work in practice. - And more specifically, how would one develop and test an application for the SE, if it requires permission by the SE owner. - You mentioned it's possible to emulate a card with some tweaking of the android source, how far could you go with this? Any pointers? Either way, thank you very much for you clarification on card emulation and the different NFC modes. Thanks, JMC On Apr 4, 2:07 pm, Michael Roland <[email protected]> wrote: > Hallo JMC, > > I think there is a big misunderstanding out there of whatcardemulation > is (and what it is not!). > > First of all, NFC has three different communication modes: > * Reader/writer mode, > * Peer-to-peer mode, and > *Card-emulationmode > > *Reader/writer mode* is used to access NFC tag (i.e. tags that comply to > the tag formats specified by the NFC Forum and contain NDEF data). > Moreover, this modes provides compatibility to existing RFID (13.56MHz, > inductive, proximity coupling)cardinfrastructures (i.e. you can > interact with contactless smart (and memory) cards, like MIFARE, > ePassports, ...) > The Nexus S supports reader/writer mode for 3 (4) contactless standards: > - ISO/IEC 14443 Type A (e.g. MIFARE) and Type B > - JIS X 6319-4 (that's FeliCa) > - ISO/IEC 15693 (that's vicinity coupling cards, which is not NFC > but uses a similar communication technique also in 13.56 MHz) > > *Peer-to-peer mode* is used for direct communication between two NFC > devices (e.g. two mobile phones, but an NFC device can be pretty much > anything). This mode lifts the restrictions imposed by an "active reader > -- passivecard" system. Thus, in a classic RFID/smartcardsystem there > is a reader device that starts and controls the communication with one > or multiple cards, and cards that process commands received by reader. > Whereas, in a peer-to-peer system any device can start (and control) the > communication with any other device. > Peer-to-peer mode is used to exchange any data between NFC devices. This > data can be as simple as NDEF messages, but it's even possible to tunnel > other network protocols like IP over a peer-to-peer link. > The Nexus S supports the peer-to-peer protocol (NFC-DEP, ISO/IEC 18092) > with LLCP (NFC Logical Link Control Protocol) on top. With the current > API level only a simple exchange of NDEF messages (with Android's > proprietary protocol on top of LLCP) is possible. > > *Card-emulationmode* is used to emulate a contactless smartcardwith > an NFC device. This mode provides compatibility to existing RFID > (13.56MHz, inductive, proximity coupling) reader infrastructures. An NFC > device incard-emulationmode acts the same as any "real" contactless > smartcard. > Withcardemulationit is important to notice the difference between a > _contactless smart card_ and an _NFC tag_: > > - An NFC tag is a contactless transponder that has a certain memory > layout and contains standardized data elements (NDEF messages). > Four such layouts are defined by the NFC Forum (tag types 1 to 4). > Tag type 1 is based on Innovision's Jewel tags, tag type 2 is > based on NXP's MIFARE Ultralight. So I would not consider these > two "smart" cards (they are more like simple memory cards). Tag > type 3 is based on FeliCa and tag type 4 is based on the ISO/IEC > 7816-4 smartcardstandard. Therefore, the latter certainly are > smart cards. Yet, in this case an NFC tag is a smartcardwith a > specific file layout (i.e. acardthat contains the "NDEF > application"). > Besides the standardized NFC tag formats, vendors like NXP have > created guidelines for using their contactlesscardtechnologies > (e.g. MIFARE Classic) as NFC tags. > An NFC tag is only data storage and doesn't have (may have but > not use) special security features like data encryption, ... > > - A smartcardcan be much more than an NFC tag. A smartcardcan > contain, for instance, a credit/debitcardapplication, a > ticketing application for public transport ... > These applications have even existed before NFC. They DO NOT use > the NDEF format to exchange data. Instead they use their own > protocols (e.g. EMV for payment cards). Often they use special > security features of smart cards (high security execution > environment, highly secure data storage, cryptographic > processing power ...) > > So thecard-emulationmode allows theemulationof a contactless msartcard(and > not an NFC tag, although the smartcardcould *possibly* be > used as NFC tag). As applications like credit cards typically have high > security requirements,cardemulationis not handled by the NFC device > itself (i.e. the application processor of an NFC-enabled mobile phone). > Instead, the NFC device has a dedicated hardware component (the > so-called Secure Element) that handles all thecardemulation. (*) > > (*) This is not entirely true, as some NFC controllers (like the > PN544) would theoretically allow theemulationof ISO/IEC > 14443-4 contactelss smart cards from the application processor. > Yet, I don't know of any NFC phone that makes this functionality > available to the user and I rather doubt that this will become > available on the Nexus S. > > The Secure Element (SE) is typically a smartcarditself. But instead of > a normal contact/contactless smartcardinterface it has a connection to > the NFC controller, which connects it to the NFC antenna. > > The Nexus S has an integrated SE (a SmartMX combined into the same > package as the PN544 NFC controller). This SmartMX emulates a ISO/IEC > 14443 (Type A) smartcardand a MIFARE Classiccard. > In addition to this integrated SE it is possible to use a special UICC > (also known as SIMcard) that supports the Single Wire Protocol (which > is an interface designed for the communiction between the NFC controller > and a UICC) as the SE. > > So the Nexus S will definitly support theemulationof contactless smart > cards (with a bit of tweaking the Android sourcesthis is already > possible to some extent). Yet, the SE is a protected environmentwhere > you can't simply install your application. Instead, you have to ask the > owner for permission to install your application. The "owner is not the > user who bought the device but instead the device's vendor. So, for the > internal SE of the Nexus S it is Samsung/Google(?) who decide who gets > access to the SE. For the UICC it is your telco who decides this. > > As a consequence an "NDEF application" will most likely not make it into > the SE. So you won't be able to use your phone as *NFC tag*. But there > is not much use for this anyways as a device that understands NDEF would > most likely be an NFC device that also supports peer-to-peer mode. > > To summarize this,cardemulationwill certainly become available for > the applications you mentioned. But it will not be used to transport > *NDEF data* between devices. > > br, > Michael > > On 02.04.2011 22:45 JMC114 wrote: > > > > > > > > > Hey Michael, > > > Why - may I ask - do you think this possibility will not be made > > available to android phones? It seems to me it's a rather important > > part of NFC. The part where it makes phones compatible to existing > > infrastructures based on RFID (without changing those > > infrastructures), namely those in public transport, building access, > > charge points for electric driving, etc. > > > I - for one - believe the general public's adoption of NFC technology > > strongly depends on this. > > > Thoughts? > > > Gr, > > JMC > > > On Mar 23, 11:03 am, Michael Roland <[email protected]> wrote: > >> Hallo, > > >> the current SDK does not allow you to usecardemulation. > > >> Anyways, withcard*emulation* you will not be able to simulate an > >> *NFC tag* (i.e. a tag where you store simple NDEF messages).Card > >>emulationmode allows to emulate a contactless smartcard (typically > >> used for applications with high security requirements, like credit > >> cards). While such acard(emulated or real) can be used to carry NDEF > >> messages, I really doubt that this possibility will be made available > >> for the Android phones. > > >> br, > >> Michael > > >> On Mar 23, 5:14 am, Zhihong GUO <[email protected]> wrote: > > >>> Hi all, > > >>> about NFC in Gingerbread, is it possible to simulate a tag by the SDK? I > >>> have found the support for tag read/write and P2P push message, but > >>> haven't > >>> found any support oncardsimulate. > > >>> thanks > > >>> James -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
