405 lines
13 KiB
C++
405 lines
13 KiB
C++
--author Harald Welte <laforge@gnumonks.org>
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--title RFID / Biometric Passports
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--date 15 Oct 2005
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Starting in November, the German federal government will be issuing epectronic passports with RFID interface. All other EU member states will have to issue such passports no later than January 2007. Only Switzerland seems to have a reasonable attitude by giving their citizens a choice.
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This presentation covers technical background about the RFID technology, the ICAO MRTD specification, and the authors' efforts to develop a free software stack to use Linux to communicate with those passports.
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--footer This presentation is made with tpp http://synflood.at/tpp.html
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--newpage
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--footer RFID and Biomertic Passports
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--header Overview
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Introduction into RFID
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What is RFID
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Components of RFID System
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Protocols and Standards
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Security ISsues
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librfid - A free software RFID stack
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Data Structures
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Protocol Stack
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Interaction with OpenCT
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ePassports - Electronic Passports
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Organization of Data
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Security Features
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PKI
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Crypto Algorithms
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Security Threats
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--newpage
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--footer RFID and Biomertic Passports
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--header Introduction into RFID
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Definition of term RFID
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Radio Frequency IDentification
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RFID is one of the recent buzzwords in lots of industries, such as
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transportation
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retail sector
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governments
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Like most buzzwords, it's not very clearly defined. There is no such thing as "the RFID System. There are lots of different Systems, some standardized, most proprietary. Each of them uses it's own frequency, modulation, encoding and protocol combination. Often, systems of multiple vendors can not be used interchangibly.
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--newpage
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--footer RFID and Biomertic Passports
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--header Components of an RFID system
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Tag (Transponder)
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Serial Number Tags
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Replacement for EAN/UPC Barcodes
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WORM Tags
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Can be written once by Issuer
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Read/Write Tags
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Can be re-written many times
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Read/Write Tags with "passive" security
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Have state-machine based crypto for access control
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Cryptographic smartcards with RF Interface
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Like other crypto smartcards, just with RF interface
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--newpage
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--footer RFID and Biomertic Passports
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--header Reader
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Readers (Coupling Device)
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Readers are always called readers, even if they can write ;)
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Usually connected to a host computer via RS-323, USB or alike
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Unfortunately no standard, for API, Hardware and/or Protocol :(
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Most applications are written to vendor-provided device-specific API's
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One exception: Readers for Smartcards with RF-Interface (use PC/SC)
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--newpage
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--footer RFID and Biomertic Passports
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--header RF Interface
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The RF interface is the key attribute of any RFID system.
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Parameters that determine the RF interface are
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frequency
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modulation
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operational principle
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--newpage
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--footer RFID and Biomertic Passports
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--header RF Interface
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Magnetic Coupling
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used by many of todays RFID deployment
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rely on the magnetic coupling ("transformer") principle
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Tag/Transponder has a coil antenna to pick up RF-Field of Reader
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Power for Tag/Transponder is drawn from the magnetic field
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Common systems use 125kHz (old) or 13.56MHz (current)
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Operational range often small, since high magnetic field strengh needed
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--newpage
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--footer RFID and Biomertic Passports
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--header RF Interface
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Backscatter
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Used by many RFID systems under current development
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Operate typically in UHF range (868 to 956 MHz)
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Use electric field of the reader, employ backscatter modulation
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Higher operational range (within tens of metres)
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Surface Accoustic Wave
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SAW tags use low-power microwave radio signals
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Tag/Transponder converts it to untrasonic signals (piezo crystal)
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Variations of the reflected signal used to provide a unique number
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--newpage
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--footer RFID and Biomertic Passports
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--header Protocols and Standards
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Apart from the various vendor proprietary protocols, there are some ISO standards
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ISO 11784 / 11785
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Identification of Animals
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134.2kHz, magnetic coupling, load modulation, 4191 bps
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ISO 14223
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Extension of 11784/11785 and allows for more data
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ISO 10536
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"close coupling" smart cards, range up to 1cm
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Inductive or capacitive coupling at 4.9152MHz
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Never attained any significant market share
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ISO 18000 series
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Current development of international "Auto-ID" standard
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Includes operation on 13.56MHz, 2.4GHz, 868/956MHz
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Not yet deployed
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--newpage
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--footer RFID and Biomertic Passports
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--header Protocols and Standards
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ISO 14443
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"proximity coupling ID cards"
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Range of up to 10cm
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Two variants: 14443-A and 14443-B
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Both use 13.56MHz, but different parameters (see paper for details)
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Specifies physical layer, link-layer (anticollision)
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Specifies an optional transport level protocol (ISO 14443-4)
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Speed up to 848kbits/sec
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ISO 15693
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"vicinity coupling", range up to 1m
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Like ISO 14443, operates on 13.56MHz, magnetic coupling
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Data rate 1.65kbits/sec or 26.48kbits/sec
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Because of long distance, very little power
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Therefore only used for passive tags
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--newpage
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--footer RFID and Biomertic Passports
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--header Protocols and Standards
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ISO 14443-A Details
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Anti-Collision is based on binary search
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Manchester Encoding allows reader to detect bit collisions
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Reader can transmit bit-frames of variable length
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1. Reader sends REQA / WUPA
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2. All transpondesr in range will reply with their address (UID)
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3a. If there is no collision, send SELECT comamand on full UID
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3b. If there is a collision, transmit bit frame which forces bit of collision to 0 or 1
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4. Loop
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--newpage
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--footer RFID and Biomertic Passports
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--header Protocols and Standards
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ISO 14443-B Details
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Anti-Collision is based on "Slotted ALOHA" protocol
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Based in probabilistic scheme
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Reader sends REQB/WUPB command with number of available slots
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Every transponder chooses it's own number (rnd() % slots)
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If there is a collision, we simply retry.
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Result:
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Both 14443-A and 14443-B anti collision are subject to DoS
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"blocker tags" have already been demonstrated.
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--newpage
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--footer RFID and Biomertic Passports
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--header Closer look on Readers
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There's a variety of readers for the 13.56MHz world
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Usually they all use one of the (small number of) available ASIC's
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Reader ASIC's integrate analog and digital part and have standard bus interface
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End-User Reader products contain such an ASIC plus a microcontroller
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Active Readers
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e.g. "Philips Pegoda"
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Run the RFID protocol stack on the microcontroller
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Passive Readers
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e.g. "Omnikey CardMan 5121"
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Run the RFID protocol on the host system
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Passive readers obviously provide higher flexibility and are cheaper.
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--newpage
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--footer RFID and Biomertic Passports
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--header Security Issues
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Eavesdropping
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Channel from reader to tag can be easily sniffed (even > 10m)
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Channel from tag to reader is difficult (Author has managed 3m)
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Denial of Service
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Anti-collision mechanism used to distinguish between multiple tags
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Using a "fake tag" you can create Denial of Service
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Products such as "blocker tags" have already been presented
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Authenticity/Confidentiality
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None of the existing standards offers any kind of crypto
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Standards-compliant systems like passports use crypto at layer 5
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Lots of proprietary "closed algorithm" vendor products with questionable security
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--newpage
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--footer RFID and Biomertic Passports
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--header librfid - A Free Software RFID stack
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The librfid project intends to provide a free software reader-side implementation of common RFID protocols such as ISO 14443 and ISO 15693
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Various abstraction layers and plugin interface allows for later addition of new protocols an readers.
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Optionally integrates with OpenCT.
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--newpage
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--footer RFID and Biomertic Passports
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--header librfid - A Free Software RFID stack
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struct rfid_asic
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Contains all routines for a specific reader asic
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Currently only Philips CL RC 632 supported
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struct rfid_asic_transport
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A transport that gives access to the ASIC registers
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struct rfid_reader
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A container for rfid_asic and rfid_asic_transport
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struct rfid_layer2
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An anticollision protocol such as ISO 14443-3A/B
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struct rfid_protocol
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A transport protocol suhc as ISO 14443-4
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--newpage
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--footer RFID and Biomertic Passports
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--header librfid - A Free Software RFID stack
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Typical Protocol Stack
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rfid_protocol_stack
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CM5121 Reader
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CL RC632 ASIC
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PC_to_RDR_Escape transport
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USB-CCID driver of OpenCT
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libusb
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--newpage
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--footer RFID and Biomertic Passports
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--header librfid - A Free Software RFID stack
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Application Interface
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Native API
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librfid-specific API
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quite low-level
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requires application to know a lot about the stack
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OpenCT, PC/SC, CT-API
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OpenCT integration provides PC/SC and CT-API for crypto smarcards
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Is currently under development
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--newpage
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--footer RFID and Biomertic Passports
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--header Electronic Passports
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Electronic Passports (ePassports) are officially called MRTD
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MRTD: Machine Readable Travel Document
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Specifications by ICAO (International Civil Aviation Organization)
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Basic idea
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store passport data and additional biometrics on Transponder
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alternate storage methods such as 2D barcodes covered, too
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common standard for interoperability
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some features required, others optional (up to issuing country)
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--newpage
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--footer RFID and Biomertic Passports
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--header Electronic Passports
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Organization of Data
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According to LDS (Logical Data Structure) specification
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Data is stored in DG (Data Groups)
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DG1: MRZ information (mandatory)
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DG2: Portrait Image + Biometric template (mandatory)
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DG3-4: fingerprints, iris image (optional)
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EF.SOD: Security Object Data (cryptographic signatures)
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EF.COM: Lists with Data Groups Exist
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All data is stored in BER-encoded ASN.1
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just think of all the ASN.1 parser bugs...
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DG2-DG4 are encoded as CBEFF (common biometric file format, ISO 19785)
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--newpage
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--footer RFID and Biomertic Passports
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--header Electronic Passports
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Security Features
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Randomization of Serial Number
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Usually all ISO 14443 transponders have a unique serial number
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This serial number is part of the anticollision procedure
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Problem: Pseudonymized Tracking
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ICAO MRTD specs don't require unique serial number
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Therefore, some countries will generate random serial numbers
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--newpage
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--footer RFID and Biomertic Passports
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--header Electronic Passports
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Security Features
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Passive Authentication (mandatory)
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Proves that passport data is signed by issuing country
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Inspection System verifies signature of DG's
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EF.SOD contains individual signature for each DG
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EF.SOD itself is signed
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Document Signer Public Key from PKD / bilateral channels
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Document Signer Public Key also stored on Passport (optional)
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Useful only if Country Root CA public key known
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--newpage
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--footer RFID and Biomertic Passports
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--header Electronic Passports
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Security Features
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Active Authentication (optional)
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Verifies that chip has not been substituted
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Uses challenge-response protocol between reader and chip
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DG15 contains KPuAA
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KPrAA is stored in secure memory of the chip
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PPuAA is signed in EF.SOD
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--newpage
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--footer RFID and Biomertic Passports
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--header Electronic Passports
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Basic Access Control (optional, implemented in .de passports)
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Denies Access to the chip until inspection system is authorized
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Authorization is performed by deriving keys from MRZ
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MRZ_info
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nine digit document number
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in many countries: issuing authority + incrementing number
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six digit date of birth
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can be guessed or assumed between
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six digit expiry date
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16most significant bytes of SHA1-hash over MRZ_info is key
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3des keys used for S/M (ISO7816 secure messaging)
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--newpage
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--footer RFID and Biomertic Passports
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--header Electronic Passports
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Extended Access Control (optional)
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Prevents unauthorized access to additional bimetrics
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Similar to Basic Access Control, but different keys
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Not internationally standardized
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Implemented by individual states
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Only shared with those states that are allowed access
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--newpage
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--footer RFID and Biomertic Passports
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--header Electronic Passports
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Encryption of Additional Biometrics (optional
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The actual payload of the CBEFF
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--newpage
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--footer RFID and Biomertic Passports
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--header Electronic Passports
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Public Key Hierarchy
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X.509 Certificates
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Every country operates it's own CA
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Document signer keys derived from CA root
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Document signer public keys are distributed publicly via ICAO PKD
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Everyone can verify
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--newpage
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--footer RFID and Biomertic Passports
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--header libmrtd - Free Software library for MRTD's
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libmtrd provides functions for
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reading out and decoding data on MRTD
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verifying data stored on MRTD
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cryptograpy compliant with MRTD specs
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basic access control
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passive authentication
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extended access control (planned)
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--newpage
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--footer RFID and Biomertic Passports
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--header libmrtd - Free Software library for MRTD's
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API towards the lower level (transport)
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PC/SC (to work with readers/drivers other than librfid)
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native librfid API
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API towards the application
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not really finished yet, lots of flux
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--newpage
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--footer RFID and Biomertic Passports
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--header libmrtd - Free Software library for MRTD's
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libmrtd status
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parsing functions for LDS
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parsing functions for DG1
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parsing functions for DG2 (CBEFF)
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basic access control (untested)
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still very early alpha stage
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contributors welcome
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no frontend application program
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--newpage
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--footer RFID and Biomertic Passports
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--header Further Reading
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The slides
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https://svn.gnumonks.org/trunk/presentation/2005/rfid-0sec2005/
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The paper
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https://svn.gnumonks.org/trunk/presentation/2005/rfid-lk2005/
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librfid code
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https://svn.gnumonks.org/trunk/librfid/
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libmrtd
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https://svn.gnumonks.org/trunk/libmrtd
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the mailinglist
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librfid-devel@lists.gnumonks.org
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https://lists.gnumonks.org/mailman/listinfo/librfid-devel
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ICAO MRTD homepage (includes all MRTD specs in PDF format)
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http://www.icao.org/
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