In the Google Wallet umbrella, so a full general purpose TSM mightiness non live an option, at to the lowest degree for a while.
Influenza A virus subtype H5N1 to a greater extent than practical alternative for third-party developers is software carte du jour emulation. In this mode, the emulated carte du jour is non on a SE, but is genuinely implemented every bit a regular Android app. Once the NFC fight senses an external reader, it forwards communication to a registered app, which processes it too returns a reply which the NFC fight but relays. This manifestly doesn't offering the same safety every bit an SE, but comes alongside the wages of non having to bargain alongside MNOs, vendors or TSMs. This vogue is non available inwards stock Android (and is unlikely to locomote into inwards the mainstream), but has been integrated into CyanogenMod too in that place are already commercial services that utilisation it. For to a greater extent than information on the safety implications of software carte du jour emulation, meet this first-class paper.
The previous post we gave a brief introduction of secure chemical element (SE) back upwards inwards mobile devices too showed how to communicate alongside the embedded SE inwards Android 4.x We'll instantly hand to sending about actual command to the SE inwards gild to discovery out to a greater extent than information well-nigh its OS too installed applications. Finally, nosotros volition hash out options for installing custom applets on the SE.
The master copy ISO 7816 standards were developed for contact cards, but the same APDU-based communication model is used for contactless cards every bit well. It is layered on meridian of the wireless transmission protocol defined past times ISO/IEC 14443-4 which behaves much similar T=1 for contact cards.
Influenza A virus subtype H5N1 to a greater extent than practical alternative for third-party developers is software carte du jour emulation. In this mode, the emulated carte du jour is non on a SE, but is genuinely implemented every bit a regular Android app. Once the NFC fight senses an external reader, it forwards communication to a registered app, which processes it too returns a reply which the NFC fight but relays. This manifestly doesn't offering the same safety every bit an SE, but comes alongside the wages of non having to bargain alongside MNOs, vendors or TSMs. This vogue is non available inwards stock Android (and is unlikely to locomote into inwards the mainstream), but has been integrated into CyanogenMod too in that place are already commercial services that utilisation it. For to a greater extent than information on the safety implications of software carte du jour emulation, meet this first-class paper.
Summary
We showed that the SE inwards recent Android phones offers a Java Card-compatible execution surroundings too implements GlobalPlatform specifications for carte du jour too applet management. Those require authentication using surreptitious keys for all operations that alter the carte du jour state. Because the keys for Android's SE are alone available to Google too their partners, it is currently impossible for 3rd parties to install applets on the SE, but that could alter if full general purpose TSM services targeting Android devices locomote available.The previous post we gave a brief introduction of secure chemical element (SE) back upwards inwards mobile devices too showed how to communicate alongside the embedded SE inwards Android 4.x We'll instantly hand to sending about actual command to the SE inwards gild to discovery out to a greater extent than information well-nigh its OS too installed applications. Finally, nosotros volition hash out options for installing custom applets on the SE.
SE execution environments
The Android SE is essentially a smart carte du jour inwards a different package, so most standards too protocols originally developed for smart cards apply. Let's briefly review the relevant ones.
Smart cards accept traditionally been file system-oriented too the chief role of the OS was to handgrip file access too enforce access permissions. Newer cards back upwards a VM running on meridian of the native OS that allows for the execution of 'platform independent' applications called applets, which brand utilisation of a good defined runtime library to implement their functionality. While different implementations of this image exists, past times far the most pop i is the Java Card runtime surroundings (JCRE). Applets are implemented inwards a restricted version of the Java linguistic communication too utilisation a subset of the runtime library, which offers basic classes for I/O, message parsing too cryptographic operations. While the JCRE specification fully defines the applet runtime environment, it does non specify how to load, initialize too delete applets on actual physical cards (tools are alone provided for the JCRE emulator). Since i of the chief applications of smart cards are diverse payment services, the application loading too initialization (often referred to every bit 'card personalization') procedure needs to live controlled too alone authorized entities should live able to alter the card's too installed applications' state. Influenza A virus subtype H5N1 specification for securely managing applets was originally developed past times Visa nether the call Open Platform, too is instantly beingness maintained too developed past times the GlobalPlatform (GP) organization nether the call 'GlobalPlatform Card Specification' (GPCS).
The Card Specification, every bit anything developed past times a committee, is quite extensive too spans multiple documents. Those are quite abstract at times too brand for a fun read, but the heart too soul is that the carte du jour has a mandatory Card Manager factor (also referred to every bit the 'Issuer Security Domain') that offers a good defined interface for carte du jour too private application life wheel management. Executing Card Manager operations requires authentication using cryptographic keys saved on the card, too so alone an entity that knows those keys tin alter the solid ground of the carte du jour (one of OP_READY, INITIALIZED, SECURED, CARD_LOCKED or TERMINATED) or create out applets. Additionally the GPCS defines secure communication protocols (called Secure Channel, SC) that likewise authentication offering confidentiality too message integrity when communicating alongside the card.
SE communication protocols
As nosotros showed inwards the previous post, Android's interface for communicating alongside the SE is thebyte[] transceive(byte[] command) method of the NfcExecutionEnvironment class. The construction of the exchanged messages, called APDUs (Application Protocol Data Unit) is defined inwards the ISO/IEC 7816-4: Organization, safety too commands for interchange standard. The reader (also known every bit a Card Acceptance Device, CAD) sends command APDUs (sometimes referred to every bit C-APDUs) to the card, comprised of a mandatory 4-byte header alongside a command flat (CLA), pedagogy (INS) too ii parameters (P1 too P2). This is followed past times the optional command information length (Lc), the actual information too live on the maximum pose out of reply bytes expected, if whatever (Le). The carte du jour returns a reply APDU (R-APDU) alongside a mandatory condition give-and-take (SW1 too SW2) too optional reply data. Historically, command APDU information has been express to 255 bytes too reply APDU information to 256 bytes. Recent cards too readers back upwards extended APDUs alongside information length upwards to 65536 bytes, but those are non ever usable, by too large for diverse compatibility reasons. The lower flat communication betwixt the reader too the carte du jour is carried out past times i of several transmission protocols, the most widely used ones beingness T=0 (byte-oriented) too T=1 (block-oriented). Both are defined inwards ISO 7816-3: Cards alongside contacts — Electrical interface too transmission protocols. The APDU central is non completely protocol-agnostic, because T=0 cannot direct ship reply data, but alone notify the reader of the pose out of available bytes. Additional command APDUs (GET RESPONSE) ask to live sent inwards gild to recall the reply data.The master copy ISO 7816 standards were developed for contact cards, but the same APDU-based communication model is used for contactless cards every bit well. It is layered on meridian of the wireless transmission protocol defined past times ISO/IEC 14443-4 which behaves much similar T=1 for contact cards.
Exploring the Milky Way Nexus SE execution environment
With most of the theory out of the way, it is fourth dimension to teach our hands muddy too live on seek to communicate alongside the SE. As mentioned inwards the previous post, the SE inwards the Milky Way Nexus is a fight from NXP's Google Wallet umbrella, so a full general purpose TSM mightiness non live an option, at to the lowest degree for a while.
Influenza A virus subtype H5N1 to a greater extent than practical alternative for third-party developers is software carte du jour emulation. In this mode, the emulated carte du jour is non on a SE, but is genuinely implemented every bit a regular Android app. Once the NFC fight senses an external reader, it forwards communication to a registered app, which processes it too returns a reply which the NFC fight but relays. This manifestly doesn't offering the same safety every bit an SE, but comes alongside the wages of non having to bargain alongside MNOs, vendors or TSMs. This vogue is non available inwards stock Android (and is unlikely to locomote into inwards the mainstream), but has been integrated into CyanogenMod too in that place are already commercial services that utilisation it. For to a greater extent than information on the safety implications of software carte du jour emulation, meet this first-class paper.
The final part of the serial volition facial expression into the electrical flow Google Wallet implementation too explore how it makes utilisation of the SE.
Influenza A virus subtype H5N1 to a greater extent than practical alternative for third-party developers is software carte du jour emulation. In this mode, the emulated carte du jour is non on a SE, but is genuinely implemented every bit a regular Android app. Once the NFC fight senses an external reader, it forwards communication to a registered app, which processes it too returns a reply which the NFC fight but relays. This manifestly doesn't offering the same safety every bit an SE, but comes alongside the wages of non having to bargain alongside MNOs, vendors or TSMs. This vogue is non available inwards stock Android (and is unlikely to locomote into inwards the mainstream), but has been integrated into CyanogenMod too in that place are already commercial services that utilisation it. For to a greater extent than information on the safety implications of software carte du jour emulation, meet this first-class paper.
Summary
We showed that the SE inwards recent Android phones offers a Java Card-compatible execution surroundings too implements GlobalPlatform specifications for carte du jour too applet management. Those require authentication using surreptitious keys for all operations that alter the carte du jour state. Because the keys for Android's SE are alone available to Google too their partners, it is currently impossible for 3rd parties to install applets on the SE, but that could alter if full general purpose TSM services targeting Android devices locomote available.The final part of the serial volition facial expression into the electrical flow Google Wallet implementation too explore how it makes utilisation of the SE.
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android security
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