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  CORE Working Group                                           P. Urien
  Internet Draft                                      Telecom ParisTech
  Intended status: Experimental

                                                              June 2017
  Expires: December 2017

                           Remote APDU Call Secure (RACS)
                           draft-urien-core-racs-09.txt


Abstract

   This document describes the Remote APDU Call Protocol Secure (RACS)
   protocol, dedicated to Grid of Secure Elements (GoSE). These servers
   host Secure Elements (SE), i.e. tamper resistant chips offering
   secure storage and cryptographic resources.

   Secure Elements are microcontrollers whose chip area is about 25mm2;
   they deliver trusted computing services in constrained environments.

   RACS supports commands for GoSE inventory and data exchange with
   secure elements. It is designed according to the representational
   State Transfer (REST) architecture. RACS resources are identified by
   dedicated URIs. An HTTP interface is also supported.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF). Note that other groups may also distribute
   working documents as Internet-Drafts. The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents
   at any time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 2017.

   .



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Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with
   respect to this document. Code Components extracted from this
   document must include Simplified BSD License text as described in
   Section 4.e of the Trust Legal Provisions and are provided without
   warranty as described in the Simplified BSD License.







































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Table of Contents
   Abstract........................................................... 1
   Requirements Language.............................................. 1
   Status of this Memo................................................ 1
   Copyright Notice................................................... 2
   1 Overview......................................................... 5
      1.1 What is a Secure Element.................................... 5
      1.2 Grid Of Secure Elements (GoSE).............................. 6
      1.3 Secure Element Identifier (SEID)............................ 7
          1.3.1 SlotID example ....................................... 7
          1.3.2 SEID for Secure Elements ............................. 8
      1.4 APDUs....................................................... 9
          1.4.1 ISO7816 APDU request ................................. 9
          1.4.2 ISO7816 APDU response ................................ 9
   2 The RACS protocol............................................... 10
      2.1 Structure of RACS request.................................. 10
      2.2 Structure of a RACS response............................... 11
          2.2.1 BEGIN Header ........................................ 11
          2.2.2 END Header .......................................... 11
          2.2.3 Status line ......................................... 11
          2.2.4 Examples of RACS responses: ......................... 12
      2.3 RACS request commands...................................... 12
          2.3.1 BEGIN ............................................... 12
          2.3.2 END ................................................. 12
          2.3.3 The APPEND parameter ................................ 13
          2.3.4 GET-VERSION ......................................... 14
          2.3.5 SET-VERSION ......................................... 14
          2.3.6 LIST ................................................ 15
          2.3.7 RESET ............................................... 15
          2.3.8 APDU ................................................ 16
          2.3.9 SHUTDOWN ............................................ 19
          2.3.10 POWERON ............................................ 20
          2.3.11 ECHO ............................................... 21
      2.4 Status header encoding..................................... 21
          2.4.1 Event class ......................................... 22
          2.4.2 Command class ....................................... 22
   3 URI for the GoSE................................................ 23
   4 HTTP interface.................................................. 23
      4.1 HTTPS Request.............................................. 23
      4.2 HTTPS response............................................. 24
   5 Security Considerations......................................... 24
      5.1 Authorization.............................................. 24
      5.2 Secure Element access...................................... 24
      5.3 Applications security policy............................... 25
          5.3.1 Users-Table ......................................... 25
          5.3.2 SEID-Table .......................................... 25
          5.3.3 APDU-Table .......................................... 25
      5.4 Overview of the security policy............................ 26
   6 IANA Considerations............................................. 26
   7 References...................................................... 26
      7.1 Normative References....................................... 26

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      7.2 Informative References..................................... 26
   8 Authors' Addresses.............................................. 27


















































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1 Overview

   This document describes the Remote APDU Call Protocol Secure (RACS)
   protocol, dedicated to Grids of Secure Elements (GoSE). These
   servers host Secure Elements (SE), i.e. tamper resistant chips
   offering secure storage and cryptographic resources.

   Secure Elements are microcontrollers whose chip area is about 25mm2;
   they deliver trusted computing services in constrained environments.

   RACS supports commands for GoSE inventory and data exchange with
   secure elements.

   RACS is designed according to the representational State Transfer
   (REST) architecture [REST], which encompasses the following
   features:
   - Client-Server architecture.
   - Stateless interaction.
   - Cache operation on the client side.
   - Uniform interface.
   - Layered system.
   - Code On Demand.

1.1 What is a Secure Element

   A Secure Element (SE) is a tamper resistant microcontroller equipped
   with host interfaces such as [ISO7816], SPI (Serial Peripheral
   Interface) or I2C (Inter Integrated Circuit).

   The typical area size of these electronic chips is about 25mm2. They
   comprise CPU (8, 16, 32 bits), ROM (a few hundred KB), nonvolatile
   memory (EEPROM, FLASH, a few hundred KB) and RAM (a few ten KB).
   Security is enforced by multiple hardware and logical
   countermeasures.

   According to the [EUROSMART] association height billion of such
   secure devices were shipped in 2013. Secure elements are widely
   deployed for electronic payment (EMV cards), telecommunication (SIM
   modules), identity (electronic passports), ticketing, and access
   control.

   Most of secure elements include a Java Virtual Machine and therefore
   are able to execute embedded program written in the JAVACARD
   language. Because these devices are dedicated to security purposes
   they support numerous cryptographic resources such as digest
   functions (MD5, SHA1, SHA2...), symmetric cipher (3xDES, AES) or
   asymmetric procedures (RSA, ECC).

   A set of Global Platform [GP] standards control the lifecycle of
   embedded software, i.e. application downloading, activation and
   deletion.

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   As an illustration a typical Secure Element has the following
   characteristics:

   - JAVACARD operating system;
   - Compliant with the GP (Global Platform) standards;
   - 160 KB of ROM;
   - 72 KB of EEPROM;
   - 4KB of RAM;
   - Embedded crypto-processor;
   - 3xDES, AES, RSA, ECC;
   - Certification according to Common Criteria (CC) EAL5+ level;
   - Security Certificates from payment operators.

1.2 Grid Of Secure Elements (GoSE)

                         Grid Of Secure Elements
             +---------------------------------------------+
             |                             SlotID          |
             | Grid      +------+         +------+ SEID    |
             | Inventory |      |----+    |      |----+    |
             |  |        | SLOT | SE |    | SLOT | SE |    |
       +-+-+-+--|-+      |      |----+    |      |----+    |
       |I|T|T|    |      +------+         +------+         |
       |P|C|L|RACS|                                        |
       | |P|S|    |      +------+         +------+         |
       +-+-+-+--|-+      |      |----+    |      |----+    |
             |  |        | SLOT | SE |    | SLOT | SE |    |
             |  |        |      |--+-+    |      |----+    |
             |  |        +------+  |      +------+         |
             |  +-ISO7816 Requests-+                       |
             +---------------------------------------------+

   Figure 1. Architecture of a Grid of Secure Elements


                              +----+----+----+
                         Vcc->|    |         |<-Ground
                              +----+    +----+
                       RESET->|    |    |    |
                              +----+    +----+
                       Clock->|    |    |    |<-Input/Output
                              +----+    +----+
                              |    |    |    |
                              +----+----+----+

   Figure 2. Illustration of an ISO7816 Secure Element

   A grid of Secure Elements (GoSE) is a server hosting a set of secure
   elements.



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   The goal of these platforms is to deliver trusted services over the
   Internet. These services are available in two functional planes,
   - The user plane, which provides trusted computing and secure
   storage.
   - The management plane, which manages the lifecycle (downloading,
   activation, deletion) of applications hosted by the Secure Element.

   A grid of Secure Elements offers services similar to HSM (Hardware
   Secure Module), but may be managed by a plurality of administrators,
   dealing with specific secure microcontrollers.

   According to this draft all accesses to a GoSE require the TCP
   transport and are secured by the TLS [TLS 1.0] [TLS 1.1] [TLS 2.0]
   protocol.

   The RACS protocol provides all the features needed for the remote
   use of secure elements, i.e.
   - Inventory of secure elements
   - Information exchange with the secure elements


1.3 Secure Element Identifier (SEID)

   Every secure element needs a physical slot that provides electrical
   feeding and communication resources. This electrical interface is
   for example realized by a socket soldered on an electronic board, or
   a CAD (Card Acceptance Device, i.e. a reader) supporting host buses
   such as USB.

   Within the GoSE each slot is identified by a SlotID (slot
   identifier) attribute, which may be a socket number or a CAD name.

   The SEID (Secure Element IDentifier) is a unique identifier
   indicating that a given SE is hosted by a GoSE. It also implicitly
   refers the physical slot (SlotID) to which the SE is plugged.

   The GoSE manages an internal table that establishes the relationship
   between SlotIDs and SEIDs.

   Therefore three parameters are needed for remote communication with
   secure element, the IP address of the GoSE, the associated TCP port,
   and the SEID.

  1.3.1 SlotID example

   According to the PC/SC (Personal Computer/Smart Card) standard
   [PS/SC], a smart card reader MAY include a serial number. This
   attribute (VENDOR-IFD-SERIAL) is associated to the tag 0x0103 in the
   class VENDOR-INFO.



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  1.3.2 SEID for Secure Elements

   According to the Global Platform standard [GP] the Issuer Security
   Domain (ISD) manages applications lifecycle (downloading,
   activation, deletion). The command 'initialize update' is used to
   start a mutual authentication between the administration entity and
   the secure element; it collects a set of data whose first ten bytes
   are called the 'key diversification data'. This information is used
   to compute symmetric keys, and according for example to [EMV] MAY
   comprise a serial number.










































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1.4 APDUs

   According to the [ISO7816] standards secure element process ISO7816
   request messages and return ISO7816 response messages, named APDUs
   (application protocol data unit).


  1.4.1 ISO7816 APDU request

   An APDU request comprises two parts: a header and an optional body.

   The header is a set of four or five bytes noted CLA INS P1 P2 P3

   - CLA indicates the class of the request, and is usually bound to
   standardization committee (00 for example means ISO request).
   -INS indicates the type of request, for example B0 for reading or D0
   for writing.
   - P1 P2 gives additional information for the request (such index in
   a file or identifier of cryptographic procedures)
   - P3 indicates the length of the request body (from P3=01 to P3=FF),
   or the size of the expected response body (a null value meaning 256
   bytes). Short ISO7816 requests may comprise only 4 bytes
   - The body may be empty. Its maximum size is 255 bytes

  1.4.2 ISO7816 APDU response

   An APDU response comprises two parts an optional body and a
   mandatory status word.

   - The optional body is made of 256 bytes at the most.

   - The response ends by a two byte status noted SW. SW1 refers the
   most significant byte and SW2 the less significant byte.

   An error free operation is usually associated to the 9000 status
   word. Following are some interpretations of the tuple SW1, SW2
   according to various standards:

   - '61' 'xx', indicates that xx bytes (modulus 256) are ready for
                reading. Operation result MUST be fetched by the ISO
                Get Response APDU (CLA=00, INS=C0, P1=P2=00, P3=XX)
   - '9F' 'xx', indicates that xx bytes (modulus 256) are ready for
                reading. Operation result MUST be fetched by the ISO
                Get Response APDU (CLA=00, INS=C0, P1=P2=00, P3=XX)
   - '6C' 'XX', the P3 value is wrong, request must be performed
                again with the LE parameter value sets to 'XX'
   - '6E' 'XX', wrong instruction class (CLA) given in the request
   - '6D' 'XX', unknown instruction code (INS) given in the request
   - '6B' 'XX', incorrect parameter P1 or P2
   - '67' 'XX', incorrect parameter P3
   - '6F' 'XX', technical problem, not implemented...

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2 The RACS protocol

   +-----------------+
   |       RACS      |
   +-----------------+
   |       TLS       |
   +-----------------+
   |       TCP       |
   +-----------------+
   |       IP        |
   +------------- ---+

   Figure 2. The RACS stack

   The RACS protocol works over the TCP transport layer and is secured
   by the TLS protocol. The TLS client (i.e. the RACS client) MUST be
   authenticated by a certificate.

   One of the main targets of the RACS protocol is to efficiently push
   a set of ISO7816 requests towards a secure element in order to
   perform cryptographic operations in the user's plane. In that case a
   RACS request typically comprises a prefix made with multiple ISO7816
   requests and a suffix that collects the result of a cryptographic
   procedure.

   The mandatory use of TLS with mutual authentication based on
   certificate provides a simple and elegant way to establish the
   credentials of a RACS client over the GoSE. It also enables an easy
   splitting between users' and administrators' privileges.


2.1 Structure of RACS request

   A RACS request is a set of command lines, encoded according to the
   ASCII format. Each line ends by the Cr (carriage return) and line
   feed (Lf) characters. The RACS protocol is case sensitive.

   Each command is a set of tokens (i.e. words) separated by space
   (0x20) character(s).

   The first token of each line is the command to be executed.

   A command line MAY comprise other tokens, which are called the
   command parameters.

   A RACS request MUST start by a BEGIN command and MUST end by an END
   command.

   Each command line is associated to an implicit line number. The
   BEGIN line is associated to the zero line number.

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   The processing of a RACS request is stopped after the first error.
   In that case the returned response contained the error status
   induced by the last executed command.

2.2 Structure of a RACS response

   A RACS response is a set of lines, encoded according to the ASCII
   format. Each line ends by the Cr (carriage return) and line feed
   (Lf) characters. The RACS protocol is case sensitive.

   Each line is a set of tokens (i.e. words) separated by space (0x20)
   character(s).

   The first token of each line is the header.

   The second token of response each line is associated command line
   number

   A response line MAY comprise other tokens, which are called the
   response parameters.

   Three classes of headers are defined BEGIN, END and Status.

   A RACS response MUST start by a BEGIN header and MUST end by an END
   header. It comprises one or several status lines.


  2.2.1 BEGIN Header

   This header starts a response message.

   It comprises an optional parameter, an identifier associated to a
   previous request message.

  2.2.2 END Header

   This header ends a response message.

  2.2.3 Status line

   A status header indicates a status line.

   It begins by the character '+' in case of success or '-' if an error
   occurred during the RACS request execution. It is followed by an
   ASCII encoded integer, which is the value of the status.

   The second mandatory token of a status line is the command line
   number (starting from zero)



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   A status line MAY comprise other tokens, which are called the
   response parameters.


  2.2.4 Examples of RACS responses:


   BEGIN CrLf
   +001 000 Success CrLf
   END CrLf

   BEGIN moon1969 CrLf
   -301 007 Illegal command, BEGIN condition not satisfied at line 7
   END CrLf

   BEGIN Asterix237 CrLf
   +006 001 [ISO7816-Response] CrLf
   END CrLf

   BEGIN CrLf
   -100 002 Unknown command at line 2 CrLf
   END CrLf

   BEGIN CrLf
   -606 001 Unauthorized command APDU command at line 1
   END CrLf

   BEGIN CrLf
   -706 001 SEID Already in use, APDU command at line 1
   END CrLf


2.3 RACS request commands


  2.3.1 BEGIN

   This command starts a request message. A response message is
   returned if an error is detected.

   An optional parameter is the request identifier, which MUST be
   echoed in the parameter of the first response line (i.e. starting by
   the BEGIN header).

  2.3.2 END

   This command ends a request message. It returns the response message
   triggered by the last command.




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   Example1
   ========
   Request:
   BEGIN CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +001 000 Success CrLf
   END CrLF

   Example2
   ========
   Request:
   BEGIN Marignan1515 CrLf
   APDU ASTERIX-CRYPTO-MODULE [ISO7816-Request] CrLf
   END CrLf

   Response:
   BEGIN Marignan1515 CrLf
   +006 001 [ISO7816-Response] CrLf
   END CrLf

  2.3.3 The APPEND parameter

   The APPEND parameter MAY be used in all command lines, excepted
   BEGIN and END. The APPEND parameter MUST be the last parameter of a
   command line.
   By default a response message returns only the last status line.
   When APPEND is inserted, the command line, if executed, MUST produce
   a status line.

   Example

   Request:
   BEGIN SanchoPanza CrLf
   APDU 100 [ISO7816-Request-1] CrLf
   APDU 100 [ISO7816-Request-2] CrLf
   END CrLf

   Response:
   BEGIN SanchoPanza CrLf
   +006 002 [ISO7816-Response-2] CrLf
   END CrLf

   Request:
   BEGIN DonQuichotte CrLf
   APDU 100 [ISO7816-Request-1] APPEND CrLf
   APDU 100 [ISO7816-Request-2] APPEND CrLf
   END CrLf


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   Response:
   BEGIN DonQuichotte CrLf
   +006 001 [ISO7816-Response-1] CrLf
   +006 002 [ISO7816-Response-2] CrLf
   END CrLf


  2.3.4 GET-VERSION

   This command requests the current version of the RACS protocol.
   The returned response is the current version encoded by two integer
   separated by the '.' character. The first integer indicates the
   major version and the second integer gives the minor version.

   This draft version is 0.2

   Example
   =======
   Request:
   BEGIN CrLf
   GET-VERSION CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +002 001 1.0 CrLf
   END CrLf

  2.3.5 SET-VERSION

   This command sets the version to be used for the RACS request. An
   error status is returned by the response if an error occurred.

   Example 1
   =========
   Request:
   BEGIN CrLf
   SET-VERSION 2.0 CrLf
   END CrLf

   Response:
   BEGIN CrLf
   -403 001 Error line 1 RACS 2.0 is not supported CrLf
   END CrLf

   Example 2
   =========
   Request:
   BEGIN CrLf
   SET-VERSION 1.0 CrLf
   END CrLf

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   Response:
   BEGIN CrLf
   +003 001 RACS 1.0 has been activated CrLf
   END CrLf

  2.3.6 LIST

   This command requests the list of SEID plugged in the GoSE.

   It returns a list of SEIDs separated by space (0x20) character(s).

   Some SEID attributes MAY be built from a prefix and an integer
   suffix (such as SE#100 in which SE# is the suffix and 100 is the
   integer suffix. A list of non-consecutive SEID MAY be encoded as
   prefix[i1;i2;..;ip] where i1,i2,ip indicates the integer suffix. A
   list of consecutive SEID could be encoded as prefix[i1-ip] where
   i1,i2,ip indicates the integer suffix.


   Example 1
   =========
   Request:
   BEGIN CrLf
   LIST CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +004 001 SEID1 SEID2 CR LF
   END CrLf

   Example 2
   =========
   Request:
   BEGIN CrLf
   LIST CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +004 001 Device[1000-2000] SerialNumber[567;789;243] CrLf
   END CrLf

  2.3.7 RESET

   This command resets a secure element. The first parameter gives the
   secure element identifier (SEID). An optional second parameter
   specifies a warm reset. The default behavior is a cold reset.
   The response status indicates the success or the failure of this
   operation.

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   Syntax: RESET SEID [WARM] CrLf

   Example 1
   =========
   Request:
   BEGIN CrLf
   RESET device#45 CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +005 001 device#45 Reset Done
   END CrLf


   Example 2
   =========
   Request:
   BEGIN CrLf
   RESET device#45 CrLf
   END CrLf

   Response:
   BEGIN CrLf
   -705 001 error device#45 is already in use
   END CrLf


   Example 3
   =========
   Request:
   BEGIN CrLf
   RESET device#45 WARM CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +005 001 device#45 Warm Reset Done CrLf
   END CrLf

  2.3.8 APDU

   This command sends an ISO7816 request to a secure element or a set
   of ISO7816 commands.

   The first parameter specifies the SEID.
   The second parameter is an ISO7816 request.
   Three optional parameters are available; they MUST be located after
   the second parameter.


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   - CONTINUE=value, indicates that the next RACS command will be
   executed only if the ISO7816 status word (SW) is equal to a given
   value. Otherwise an error status is returned.
   - MORE=value, indicates that a FETCH request will be performed (i.e.
   a new ISO7816 request will be sent) if the first byte of the ISO7816
   status word (SW1) is equal to a given value.
   - FETCH=value fixes the four bytes of the ISO7816 FETCH request
   (i.e. CLA INS P1 P2). The default value (when FETCH is omitted) is
   00C00000 (CLA=00, INS=C0, P1=00, P2=00)

   When the options CONTINUE and MORE are simultaneously set the SW1
   byte is first checked. If there is no match then the SW word is
   afterwards checked.

   The ISO7816 6Cxx status MUST be autonomously processed by the GoSE.


   SYNTAX
   APDU SEID ISO7816-REQUEST [CONTINUE=SW] [MORE=SW1] [FETCH=CMD] CrLf

   The returned response is the ISO7816 response. If multiple ISO7816
   requests are executed (due to the MORE option), the bodies are
   concatenated in the response, which ends by the last ISO7816 status
   word.

   The pseudo code of the APDU command is the following :

   1. BODY = empty;
   2. SW   = empty;
   3. DoIt = true;
   3. Do
   4. { iso7816-response = send(iso7816-request);
   5.   body || sw1 || sw2 = iso7816-response;
   6.   If ( (first request) && (iso7816-request.size==5) &&
             (body==empty) && (sw1==6C) )
   8.   { iso7816-request.P3 = sw2 ; }
   6.   Else
   7.   { SW = sw1 || sw2
   8.     BODY = BODY || body;
   9.     If (sw1 == MORE)
   10.    { iso7816-request = FETCH || sw2 ; }
   11.    Else
   12.    { DoIt=false;}
   13.   }
   14. }
   15. While (DoIt == true)

   16. iso7816-response = BODY || SW ;
   17. If (SW != CONTINUE) Error   ;
   18. Else                No Error;


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   Example 1
   =========
   Request:
   BEGIN CrLf
   APDU SEID ISO7816-REQUEST CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +006 001 ISO7816-RESPONSE CrLf
   END CrLf


   Example 2
   =========
   Request:
   BEGIN CrLf
   APDU SEID ISO7816-REQUEST CrLf
   END CrLf

   Response:
   BEGIN CrLf
   -706 001 error SEID is already used CrLf
   END CrLf


   Example 3
   =========
   Request:
   BEGIN CrLf
   APDU SEID ISO7816-REQUEST CrLf
   END CrLf

   Response:
   BEGIN CrLf
   -606 001 error access unauthorized access CrLf
   END CrLf


   Example 4
   =========
   BEGIN CrLf
   APDU SEID ISO7816-REQUEST-1 CONTINUE=9000 CrLf
   APDU SEID ISO7816-REQUEST-2 CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +006 002 ISO7816-RESPONSE-2 CrLf
   END CrLf


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   Example 5
   =========
   BEGIN CrLf
   APDU SEID ISO7816-REQUEST-1 CONTINUE=9000 CrLf
   APDU SEID ISO7816-REQUEST-2 CrLf
   END CrLf

   Response:
   BEGIN CrLf
   -006 001 Request Error line 1 wrong SW CrLf
   END CrLf

   Example 6
   =========
   BEGIN CrLf
   APDU SEID ISO7816-REQ-1 CONTINUE=9000 CrLf
   APDU SEID ISO7816-REQ-2 CONTINUE=9000 CrLf
   APDU SEID ISO7816-REQ-3 CONTINUE=9000 MORE=61 FETCH=00C00000 CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +006 003 ISO7816-RESP-3 CrLf
   END CrLf

   Multiple ISO7816 requests have been performed by the third APDU
   command according to the following scenario :
   - the ISO7816-REQ-3 request has been forwarded to the secure element
   (SEID)
   - the ISO 7816 response comprises a body (body-0) and a status word
   (SW-0) whose first byte is 0x61, and the second byte is SW2-0
   - the FETCH command CLA=00, INS=00, P1=00, P2=00, P3=SW2-0 is sent
   to the secure element
   - the ISO 7816 response comprises a body (body-1) and a status word
   (SW-1) set to 9000

   The RACS response is set to
   +006 003 body-0 || body-1 || SW-1 CrLf
   where ||indicates a concatenation operation.


  2.3.9 SHUTDOWN

   This command powers down a secure element. The first parameter gives
   the secure element identifier (SEID).


   Syntax: SHUTDOWN SEID CrLf




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   Example
   =========
   Request:
   BEGIN Goodbye CrLf
   SHUTDOWN device#45 CrLf
   END CrLf

   Response:
   BEGIN Goodbye CrLf
   +007 001 device#45 has been powered down CrLf
   END CrLf


  2.3.10 POWERON

   This command powers up a secure element. The first parameter gives
   the secure element identifier (SEID).


   Syntax: POWERON SEID CrLf

   Example 1
   =========
   Request:
   BEGIN CrLf
   POWERON device#45 CrLf
   END CrLf

   Response:
   BEGIN CrLf
   +008 001 device#45 Has been powered up CrLf
   END CrLf

   Example 2
   =========
   Request:
   BEGIN CrLf
   POWERON device#45 CrLf
   END CrLf

   Response:
   BEGIN CrLf
   -708 001 error device#45 is already in use CrLf
   END CrLf

   Example 3
   =========
   Request:
   BEGIN CrLf
   POWERON device#45 CrLf
   END CrLf

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   Response:
   BEGIN CrLf
   -608 001 error unauthorized access CrLf
   END CrLf


  2.3.11 ECHO

   This command echoes a token. The first parameter is the token (word)
   to be echoed by the response.


   Syntax: ECHO SEID CrLf

   Example 1
   =========
   Request:
   BEGIN TestEcho CrLf
   ECHO Hello CrLf
   END CrLf

   Response:
   BEGIN TestEcho CrLf
   +009 001 Hello CrLf
   END CrLf

   Example 2
   =========
   Request:
   BEGIN ResetSEID CrLf
   POWERON device#45 CrLf
   ECHO Done CrLf
   END CrLf

   Response:
   BEGIN ResetSEID CrLf
   +009 001 Done CrLf
   END CrLf


2.4 Status header encoding

   The first token of a response line is the status header. It begins
   by a '+' or a '-' character, and comprises three decimal digits
   (xyz).

   The first digit (x) MUST indicates an event class.
   The second and third digits (yz) MAY indicate a command class.



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  2.4.1 Event class

   This draft only defines the meaning of the first digit located at
   the left most side.

   +0yz: No error
   -0yz: Command execution error
   -1yz: Unknown command, the command is not defined by this draft
   -2yz: Not implemented command
   -3yz: Illegal command, the command can't be executed
   -4yz: Not supported parameter or parameter illegal value
   -5yz: Parameter syntax error or parameter missing
   -6yz: Unauthorized command
   -7yz: Already in use, a session with this SE is already opened
   -8yz: Hardware error
   -9yz: System error


  2.4.2 Command class

   The second and third digits (yz) MAY indicates the command that
   trigged the current line status

   01 BEGIN
   02 GET-VERSION
   03 SET-VERSION
   04 LIST
   05 RESET
   06 APDU
   07 SHUTDOWN
   08 POWERON
   09 ECHO




















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3 URI for the GoSE


   The URI addressing the resources hosted by the GoSE is represented
   by the string:

   RACS://GoSE-Name:port/?request

   where request is the RACS request to be forwarded to a the GoSE.

   RACS command lines are encoded in a way similar to the INPUT field
   of an HTML form. Each command is associated to an INPUT name, the
   remaining of the command line i.e. a set of ASCII characters, is
   written according to the URL encoding rules. End of line characters,
   i.e. carriage return (Cr) and line feed (Lf) are omitted.

   As a consequence a request is written to the following syntax
   cmd1=cmd1-parameters&cmd2=cmd2-parameters

   Example:
   RACS://GoSE-Name:port/?BEGIN=&APDU=SEID%20[ISO7816-REQUEST]&END=

4 HTTP interface

   A GoSE SHOULD support an HTTP interface. RACS requests/responses are
   transported by HTTP messages. The use of TLS is mandatory.

4.1 HTTPS Request

   https://GoSE-Name:port/RACS?request

   where request is the RACS request to be forwarded to a secure
   element (SEID)

   The RACS request is associated to an HTML form whose name is "RACS".
   The request command lines are encoded as the INPUT field of an HTML
   form. Each command is associated to an INPUT name, the remaining of
   the command line i.e. a set of ASCII characters is written according
   to the URL encoding rules. End of line characters, i.e. carriage
   return (Cr) and line feed (Lf) are omitted.

   As a consequence a RACS request is written as
   https://GoSE-Name/RACS?cmd1=cmd1-parameters&cmd2=cmd2-parameters

   Example:

   https://GoSE-Name/RACS?BEGIN=&APDU=SEID%20[ISO7816-REQUEST]&END=




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4.2 HTTPS response

   The RACS response is returned in an XML document.

   The root element of the document is <RACS-Response>

   The optional parameter of the BEGIN header, is the content of the
   <begin> element.

   Each status line is the content of the <Cmd-Response> element, which
   includes the following information :

   - The status header is the content of the <status> element.

   - The line number is the content of the <line> element.

   - The other parameters of the status line are the content of the
   <parameters> element.

   The END header is associated to the element <end>

   End of line, i.e. carriage return (Cr) and line feed (Lf) characters
   are omitted.

   As a consequence a RACS response is written as :
   <RACS-Response>
   <begin>Optionnal-ID</begin>
   <Cmd-Response
   <status>+000</status>
   <line>001</line>
   <parameters>other parameters of the RACS response</parameters>
   </Cmd-Response>
   <end></end>
   </RACS-Response>

5 Security Considerations

5.1 Authorization

   A RACS client MUST be authenticated by an X509 certificate.

   The GoSE software MUST provide a mean to establish a list of SEIDs
   that can be accessed from a client whose identity is the CommonName
   (CN) attribute of its certificate. It MAY allocate a UserID (UID),
   i.e. an integer index from the certfificate common name.

5.2 Secure Element access

   The GoSE MUST manage a unique session identifier (SID) for each TLS
   session. The SID is bound to the client's certificate CommonName
   (SID(CN))

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   A secure element has two states, unlocked and locked. In the locked
   state the secure element may be only used by the SID that previously
   locked it.

   The first authorized command that successfully accesses to a SEID
   (either POWERON ,RESET, APDU) locks a secure element (SEID) with the
   current session (SID).

   The SHUTDOWN command MUST unlock a secure element (SEID).

   The end of a TLS session MUST unlock all the secure elements locked
   by the session.

5.3 Applications security policy

   According to the [ISO7816] standards each Application embedded
   within a secure element (associated to a SEID) is identified by an
   AID parameter (16 bytes at the most)

   The RACS server SHOULD support the following facilities

  5.3.1 Users-Table

   Each CN (the Users-Table primary key) is associated to a list of
   SEIDs whose access is authorized.

  5.3.2 SEID-Table

   Each AID (the SEID-Table primary key) is associated to a list of CNs
   whose access is authorized.

  5.3.3 APDU-Table

   For a given AID and an authorized CN, an APDU-Table MAY be
   available. This table acts as a firewall, which defined a set of
   forbidden ISO7816 commands.

   For example this filter could be expressed as a set of the four
   first bytes of an APDU-Prefix (CLA INS P1 P2) and a four bytes Mask
   An ISO7816-Request is firewall if:

   ISO7816-Request AND Mask IsEQUAL to APDU-Prefix










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5.4 Overview of the security policy

   The summary of the security policy is illustrated by the figure 3.

                         CN(uid)
                           /\
             TLS-Session  /  \
                         /    \
                       sid    sid
                        /\     /\
                       /  \   /  \
                     aid aid aid aid
                     /\
                    /  \
                   /    \
                APDU    APDU
                Filter  Filter

   Figure 3. Summary of the security policy

6 IANA Considerations

   This draft does not require any action from IANA.

7 References

7.1 Normative References

   [TLS 1.0] Dierks, T., C. Allen, "The TLS Protocol Version 1.0", RFC
   2246, January 1999

   [TLS 1.1] Dierks, T., Rescorla, E., "The Transport Layer Security
   (TLS) Protocol Version 1.1", RFC 4346, April 2006

   [TLS 1.2] Dierks, T., Rescorla, E., "The Transport Layer Security
   (TLS) Protocol Version 1.1", RFC 5746, August 2008

   [ISO7816] ISO 7816, "Cards Identification - Integrated Circuit Cards
   with Contacts", The International Organization for Standardization
   (ISO)

7.2 Informative References

   [REST] Fielding, R., "Architectural Styles and the Design of
   Network-based Software Architectures", 2000,
   http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm

   [GP] Global Platform Standards, http://www.globalplatform.org

   [EUROSMART] The EUROSMART association, http://www.eurosmart.com


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   [PC/SC] The PC/SC workgroup, http://www.pcscworkgroup.com

   [EMV] EMV Card Personalization Specification, Version 1.1, July 2007

8 Authors' Addresses

   Pascal Urien
   Telecom ParisTech
   23 avenue d'Italie
   75013 Paris               Phone: NA
   France                    Email: Pascal.Urien@telecom-paristech.fr









































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