About Machine Readable Travel Documents Privacy Enhancement Using - PowerPoint PPT Presentation

About Machine Readable Travel Documents Privacy Enhancement Using (Weakly) Non-Transferable Data Authentication Jean Monnerat, Serge Vaudenay , Martin Vuagnoux ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE http://lasecwww.epfl.ch/ SV 2007 About MRTD RFID Security 2007 1 / 41

ICAO-MRTD 1 Non-Transferable Proofs 2 SV 2007 About MRTD RFID Security 2007 2 / 41

ICAO-MRTD 1 Non-Transferable Proofs 2 SV 2007 About MRTD RFID Security 2007 3 / 41

ICAO-MRTD 1 ICAO-MRTD Overview Data Structures and PKI MRTD Cryptography Security and Privacy Issues Non-Transferable Proofs 2 SV 2007 About MRTD RFID Security 2007 4 / 41

Objectives to enable inspecting authorities to securely identify visitors with the help of machine-readable digital information → biometrics → contactless IC chip → digital signature + PKI maintained by UN/ICAO (International Civil Aviation Organization) SV 2007 About MRTD RFID Security 2007 5 / 41

MRTD History 1968: ICAO starts working on MRTD 1980: first standard (OCR-B Machine Readable Zone (MRZ)) 1997: ICAO-NTWG (New Tech. WG) starts working on biometrics 2001 9/11: US want to speed up the process 2004: version 1.1 of standard with ICC 2006: extended access control under development in the EU SV 2007 About MRTD RFID Security 2007 6 / 41

How to Distinguish a Compliant MRTD SV 2007 About MRTD RFID Security 2007 7 / 41

MRTD in a Nutshell MRTD MRZ LDS ❄ ❄ ❄ ❄ ❄ ❄ optical access radio access data authentication by digital signature + PKI aka passive authentication access control + key agreement based on MRZ info aka basic access control (BAC) chip authentication by public-key cryptgraphy aka active authentication (AA) SV 2007 About MRTD RFID Security 2007 8 / 41

ICAO-MRTD 1 ICAO-MRTD Overview Data Structures and PKI MRTD Cryptography Security and Privacy Issues Non-Transferable Proofs 2 SV 2007 About MRTD RFID Security 2007 9 / 41

MRZ Example document type issuing country holder name doc. number + CRC nationality date of birth + CRC gender date of expiry + CRC options + CRC SV 2007 About MRTD RFID Security 2007 10 / 41

LDS Structure DG1 (mandatory): same as MRZ DG11: add. personal detail(s) DG2 (mandatory): encoded face DG12: add. document detail(s) DG3: encoded finger(s) DG13: optional detail(s) DG4: encoded eye(s) DG14: (reserved) DG5: displayed portrait DG15: KPu AA DG16: person(s) to notify DG6: (reserved) DG7: displayed signature DG17: autom. border clearance DG8: data feature(s) DG18: electronic visa DG9: structure feature(s) DG19: travel record(s) DG10: substance feature(s) SO D (mandatory) SV 2007 About MRTD RFID Security 2007 11 / 41

SO D Structure list of hash for data groups DG1–DG15 formatted signature by DS (include: information about DS) (optional) C DS SV 2007 About MRTD RFID Security 2007 12 / 41

Hierarchy C CSCA ✲ other countries CSCA C DS DS 1 DS 2 SO D LDS 21 LDS 22 one PKI per country one CSCA (Country Signing Certificate Authority) C CSCA : self-signed CSCA public key KPu CSCA C CSCA distributed to other countries by diplomatic means possibly many DS (Document Signer) per country C DS : certificate for a DS public key KPu DS SO D : signature of (part of) LDS in MRTD SV 2007 About MRTD RFID Security 2007 13 / 41

ICAO-MRTD 1 ICAO-MRTD Overview Data Structures and PKI MRTD Cryptography Security and Privacy Issues Non-Transferable Proofs 2 SV 2007 About MRTD RFID Security 2007 14 / 41

Basic Access Control goal prevent from unauthorized access by the holder (privacy) read MRZ (OCR-B) extract MRZ info run an authenticated key exchange based on MRZ info open secure messaging based on the exchanged symmetric key → proves that reader knows MRZ info SV 2007 About MRTD RFID Security 2007 15 / 41

MRZ info PMFRADUPONT<<<<JEAN<<<<<<<<<<<<<<<<<<<<<<<<< 74HK8215<6CHE7304017M0705121<<<<<<<<<<<<<<03 document type issuing country holder name doc. number + CRC nationality date of birth + CRC gender date of expiry + CRC options + CRC SV 2007 About MRTD RFID Security 2007 16 / 41

Secure Messaging goal authentication, integrity, confidentiality of communication message message ✻ KS ENC KS ENC ❄ ❄ ❄ Enc Dec ✻ KS MAC KS MAC ❄ ❄ ✲ MAC ✲ MAC ✲ = ✻ ❄ ❄ Adversary ☛ ✕ ✻ → secure channel based on 3DES SV 2007 About MRTD RFID Security 2007 17 / 41

Passive Authentication goal authenticate LDS after getting SO D , check the included certificate C DS and the signature when loading a data group from LDS, check its hash with what is in SO D → stamp by DS on LDS SV 2007 About MRTD RFID Security 2007 18 / 41

Active Authentication goal authenticate the chip proves that ICC knows some secret key KPr AA linked to a public key KPu AA by a challenge-response protocol (KPu AA in LDS authenticated by passive authentication) → prove that the chip is not a clone SV 2007 About MRTD RFID Security 2007 19 / 41

Active Authentication Protocol IFD ICC RND . IFD F ← nonce || RND . IFD − − − − − − − − − − − − − − − − − → pick RND . IFD Σ Σ ← Sign KPr AA ( F ) ← − − − − − − − − − − − − − − − − − check SV 2007 About MRTD RFID Security 2007 20 / 41

Sequence of Steps for Identification read MRZ (OCR-B) ❄ resolve collisions to ICC ❄ yes ✲ BAC + open sec. messaging access denied? no ❄ ✛ passive authentication ❄ MRZ matches? ❄ ✲ check AA (if supplied) check biometrics SV 2007 About MRTD RFID Security 2007 21 / 41

ICAO-MRTD 1 ICAO-MRTD Overview Data Structures and PKI MRTD Cryptography Security and Privacy Issues Non-Transferable Proofs 2 SV 2007 About MRTD RFID Security 2007 22 / 41

Coming From Wireless Technology (claimed to be possible at a distance of 10m) detecting the proximity of an e-passport threat : giving valuable information to passport theafs threat : privacy (in some cases) by tracking people data skimming threat : privacy unauthorized access threat : privacy SV 2007 About MRTD RFID Security 2007 23 / 41

Coming From IC Chip too much trust in automated process, lazzy identification threat : identity theft malicious cookies put in MRTD threat : privacy dependence on the technology: DoS attack could kill the IC chip threat : waste of time at border controls abuse of automatic recognition threat : privacy leakage of digital evidence threat : privacy SV 2007 About MRTD RFID Security 2007 24 / 41

Digital Evidence: Challenge Semantics Attack challenge semantics in AA: evidence that D existed when MRTD was queried H ( D ) = RND . IFD ( D || LDS || Σ) = evidence evidence that MRTD was accessed at time t H ( social ( t − 1 )) = RND . IFD timestamp t ( social ( t − 1 ) || LDS || Σ) = evidence SV 2007 About MRTD RFID Security 2007 25 / 41

Digital Evidence: Transferable LDS Authentication signed personal data (name, age, gender, face, etc) can no longer hide/deny name, age, gender... when DG11 is used: more personal data (place of birth etc) personal profiles can be sold if they come with a proof SV 2007 About MRTD RFID Security 2007 26 / 41

ICAO-MRTD 1 Non-Transferable Proofs 2 SV 2007 About MRTD RFID Security 2007 27 / 41

ICAO-MRTD 1 Non-Transferable Proofs 2 Notions of Non-Transferability ZK Protocols for MRTD SV 2007 About MRTD RFID Security 2007 28 / 41

Mafia Fraud + Fully Non-Transferable Proof (does P know?) Mafia Prover Verifier ✛ ✲ ✛ ✲ K p � knowledge proof of knowledge ↓ proof of knowledge or of knowing a secret key attached to K p → need PKI for verifiers: maybe an overkill SV 2007 About MRTD RFID Security 2007 29 / 41

Zero-Knowledge: Offline Non-Transferability proof of knowledge ✛ ✲ Prover Verifier leaks nothing that can later be used ✛ ✲ Prover Cheater Simulator Cheater ✛ ✲ data of distribution D data of distribution D SV 2007 About MRTD RFID Security 2007 30 / 41

Sigma Protocols Prover Verifier secret : x commitment − − − − − − − − − − − − − → challenge ← − − − − − − − − − − − − − response − − − − − − − − − − − − − → check SV 2007 About MRTD RFID Security 2007 31 / 41

Example: GPS Identification Prover Verifier parameters : g , A , B , S public key : I ( I = g s ) input : I , g , A , B , S secret key : s ∈ [ 0 , S ] pick r ∈ [ 0 , A − 1 ] pick c ∈ [ 0 , B − 1 ] x x ← g r − − − → c ← − − − y check g y = xI c y ← r + cs − − − → and 0 ≤ y < A +( B − 1 )( S − 1 ) SV 2007 About MRTD RFID Security 2007 32 / 41