![Authentication and Anonymity?
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Attribute-based Authentication
- 1. Privacy-enhancing Attribute-based Authentication Presenting works of the EU Projects PrimeLife and ABC4Trust Slides provided by the IBM Research – Zurich identity and privacy team (mostly from Jan Camenisch, Anja Lehmann, Gregory Neven)
- 2. Authentication and Anonymity? [ Pictures: PCStelcom, BeautifulRailroadBridgeOverTheSilveryTay.Wordpress ]
- 3. Anja Lehmann, IBM Research – Zurich, 10.06.2011 ABC4Trust & PrimeLife Tutorial Part I: Introduction to Privacy-Preserving Authentication 1 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 4. Authentication l n tia e cred Issuer I am Alice Doe Convince me! and I'm over 18! btw … I trust the Issuer show credential User Verifier 7 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 5. Authentication credential / certificate signed list of attribute-value pairs name = Alice Doe birth date = 1973/01/26 signed by the issuer 8 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 6. Signature Scheme public key message private key priv signature Verify( , , ) = true = Sign( , priv ) 9 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 7. Signature Scheme | Unforgeability public key private key priv such that Verify( , , ) = true 10 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 8. Classical Authentication © 2009 IBM Corporation
- 9. Standard Public-Key Certificates e.g., X.509 certificates In the beginning… 12 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 10. Standard Public-Key Certificates e.g., X.509 certificates Obtaining a certificate… name = Alice Doe, birth date = 1973/01/26, pk = 13 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 11. Standard Public-Key Certificates e.g., X.509 certificates Using a certificate… linkable by certificate & public key linkable by certificate & public key name = Alice Doe, birth date = 1973/01/26, pk = full attribute disclosure full attribute disclosure 14 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 12. Standard Public-Key Certificates e.g., X.509 certificates Using a certificate again… name = Alice Doe, birth date = 1973/01/26, pk = name = Alice Doe, birth date = 1973/01/26, pk = linkable when used multiple times linkable when used multiple times 15 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 13. Privacy-Preserving Authentication © 2009 IBM Corporation
- 14. Privacy-Preserving Authentication: General Concepts Basic Functionality Minimal Disclosure Tokens Pseudonyms and Combining/Binding of Multiple Tokens Minimal Disclosure Wallets Extensions Revocation Usage Limitation Inspection ... 17 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 15. Minimal Disclosure Tokens In the beginning… 18 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 16. Minimal Disclosure Tokens Obtaining a token… name = Alice Doe, birth date = 1973/01/26, ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 17. Minimal Disclosure Tokens Using a token … ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 18. Minimal Disclosure Tokens Using a token … name = Alice Doe, birth date = 1973/01/26 issuance and showing are unlinkable issuance and showing are unlinkable ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 19. Minimal Disclosure Tokens Using a token … name = ?, birth date = 1973/01/26 selective attribute disclosure selective attribute disclosure ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 20. Minimal Disclosure Tokens Protection of user's privacy anonymity unlinkeability (single-use) selective disclosure Unforgeability of tokens ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 21. Minimal Disclosure Tokens Unforgeability: Alice should not be able to show a token that she never obtained name = Alice Doe, birth date = 1973/01/26 name = Alice Doe, birth date = 1947/01/26, ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 22. Privacy-Preserving Authentication: General Concepts Basic Functionality Minimal Disclosure Tokens Pseudonyms and Combining/Binding of Multiple Tokens Minimal Disclosure Wallets Extensions Revocation Usage Limitation Inspection ... 25 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 23. Minimal Disclosure Wallets extended version of minimal disclosure tokens: Protection of user's privacy pseudonymity unlinkeability (multi-use) using/combining multiple credentials selective disclosure Unforgeability of credentials Consistency of credentials (no sharing) 26 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 24. Minimal Disclosure Wallets In the beginning… master key = unique private identity 27 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 25. Minimal Disclosure Wallets Obtaining a credential… pseudonym = ephemeral public identity ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 26. Minimal Disclosure Wallets Obtaining a credential… name = Alice Doe, birth date = 1973/01/26, nym = ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 27. Minimal Disclosure Wallets Using a credential… ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 28. Minimal Disclosure Wallets Using a credential… selective attribute disclosure selective attribute disclosure name = ?, birth date = 1973/01/26 issuance and showing are unlinkable issuance and showing are unlinkable ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 29. Minimal Disclosure Wallets Using a credential again… name = ?, birth date = 1973/01/26 name = Alice Doe, birth date = ? multi-show unlinkability multi-show unlinkability ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 30. Minimal Disclosure Wallets Using multiple credentials… passport driver's license passport: birth date = 1973/01/26 driver's license: vehicle cat B ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 31. Minimal Disclosure Wallets Protection of user's privacy pseudonymity unlinkeability (multi-use) using/combining multiple credentials selective disclosure Unforgeability of credentials Consistency of credentials (no sharing) 34 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 32. Minimal Disclosure Wallets Sharing Prevention: Alice and Eve should not be able to share credential name = Alice Doe, birth date = 1973/01/26 name = Alice Doe, birth date = 1973/01/26 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 33. Minimal Disclosure Wallets Protection of user's privacy pseudonymity unlinkeability (multi-use) using/combining multiple credentials selective disclosure Unforgeability of credentials Consistency of credentials (no sharing) 36 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 34. Privacy-Preserving Authentication: General Concepts Basic Functionality Minimal Disclosure Tokens Pseudonyms and Combining/Binding of Multiple Tokens Minimal Disclosure Wallets Extensions Predicates over Attributes Revocation Device Binding Inspection Usage Limitation ... 37 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 35. Extended Functionality Predicates over attributes Credentials on hidden attributes Device binding Domain pseudonym Revocation of credentials Inspection of credentials/attributes Usage limitation Censorable Audit Logs ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 36. Predicate Over Attributes name = ?, birth date = 1973/01/26 > 1993/06/10 Range Proofs Age > 18, 10 < Age < 16, … is user over 18? credit card expiration date > today Set Membership status: {children, student, senior} Logical Combinations (credit card status = silver or gold) and valid driver's license ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 37. Extended Functionality Predicates over attributes Credentials on hidden attributes Device binding Domain pseudonym Revocation of credentials Inspection of credentials/attributes Usage limitation Censorable Audit Logs ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 38. Credentials on Hidden Attributes User can prove statements on hidden attributes name = Alice Doe birth date = name = Alice Doe, birth date = 1973/01/26 name = Alice Doe, birth date = 1973/01/26 similar to usage of pseudonyms = commitments to master secret ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 39. The idemix Library © 2009 IBM Corporation
- 40. Implementation available :-) Identity Mixer is an implementation of Private Credentials Provides a library with all the crypto Issuing credentials Transforming credentials according to a specified statement (policy) Includes many of the features discussed Provides a credential-based AC engine Relying party specifies attributes & credentials requirements User matches that to available credentials and generates „evidence“ Get it at www.PrimeLife.eu/opensource and use it ..as do a number of projects already :-) ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 41. Authentication/Access Control Engine ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 42. Card-based access requirements language (CARL) Policy and proof presentation in CARL and SAML/XACML • Policy: requirements on owned cards, e.g., own p::Passport issued-by admin.ch, fgov.be, governo.it own c::Creditcard issued-by visa.com, amex.com reveal c.number, c.expdate where p.name = c.name ^ p.bdate < today-18Y ^ c.expdate > today ^ p.expdate > today+1M • Authentication = claim over owned cards + evidence, e.g., own p::Passport issued-by admin.ch own c::Creditcard issued-by visa.com reveal c.number = “1234567890” reveal c.expdate = “31/12/2012” where p.name = c.name ^ p.bdate < 22/03/1993 ^ p.expdate > 22/04/2011 ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 43. IBM Identity Mixer: Framework Policy Layer Crypto Token Layer Minimal Full Direct Composed Group disclosure Credential Anonymous … schemes signatures tokens system attestation Efficient zero-knowledge proofs Signatures on Building Verifiable Pseudonyms Verifiable lists of messages Revocation blocks Encryptio0n Commitments Random Functions (Credentials) U-Prove CL Instan- sigs sigs tiations
- 44. “Token Transforming” Language Declaration{ id1:unrevealed:string; id2:unrevealed:string; id3:unrevealed:int; id4:unrevealed:enum; id5:revealed:string; id6:unrevealed:enum } ProvenStatements{ Credentials{ randName1:http://www.ch.ch/passport/v2010/chPassport10.xml = { FirstName:id1, LastName:id2, CivilStatus:id4 } randName2:http://www.ibm.com/employee/employeeCred.xml = {LastName:id2, Position:id5, Band:5, YearsOfEmployment:id3 } randName3:http://www.ch.ch/health/v2010/healthCred10.xml = { FirstName:id1, LastName:id2, Diet:id6 } } Inequalities{ {http://www.ibm.com/employee/ipk.xml, geq[id3,4]} } Commitments{ randCommName1 = {id1,id2}; randCommName2 = {id6} } Representations{ randRepName = {id5,id2; base1,base2} } Pseudonyms{ randNymName; http://www.ibm.com/employee/ } VerifiableEncryptions{ {PublicKey1, Label, id2} } Message { randMsgName = “Term 1:We will use this data only for ...” } } ABC4Trust & PrimeLife − Tutorial − 10.06.2011
- 45. Jan Camenisch, IBM Research – Zurich, 10.06.2011 ABC4Trust & PrimeLife Tutorial Questions? www.abc4trust.eu www.primelife.eu www.zurich.ibm.com/security/idemix 23 ABC4Trust & PrimeLife − Tutorial − 10.06.2011