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Is there life after X. 509 ? Security Workshop Globus World 2004 Frank Siebenlist Is there life after X. 509 ? Security Workshop Globus World 2004 Frank Siebenlist (Ph. D) Argonne National Laboratory The Globus Alliance [email protected] anl. gov http: //www. globus. org/

Objective l Provoke discussion u l So boring if we all agree The X Objective l Provoke discussion u l So boring if we all agree The X 509/PKI dream clearly never came thru… u u l Learn from deployment issues Maybe alternatives would work better X 509 is used in ways it was never intended… u l Our proxy-certs are a good example Some entertainment for the last talk on Friday late afternoon at the end of a looong conference u … plus it’s therapeutic for me rant on about this… [email protected] anl. go ATI 2004: Grid Security 2

Questions, l l l l l Questions… Why pay $20/EE-cert and 0$ for a Questions, l l l l l Questions… Why pay $20/EE-cert and 0$ for a Kerberos principal? Why are lawyers involved with CAs, but not with other authentication/assertion services? Why are there no armed guards to protect the attribute/authorization servers? Is the Subject’s DN ever meant to be readable? Who are the poor people that use DNs? Why do username/password systems work? Why doesn’t everyone check revocation in real-time? How many more RFCs is PKIX going to produce? What is that “pixie-dust” on those X. 509 certs? Will my children in 20 years still suffer from X. 509? [email protected] anl. go ATI 2004: Grid Security 3

X. 509 Certificate l Trusted third party (CA) vouches that combination of a public X. 509 Certificate l Trusted third party (CA) vouches that combination of a public key and some (identity) information applies to the subject that can prove the possession of the associated private key. u u l l “Vouching” through signing Implicit trust of CA CA signature “binds” identity information to public key CA responsible for revocation/renewal [email protected] anl. go ATI 2004: Grid Security Certificate Identity Info (DN & other stuff) Public Key CA Identifier CA Signature 4

X. 509 Identity Certificate l l Vetting of the “real” identity by a RA X. 509 Identity Certificate l l Vetting of the “real” identity by a RA Binding of the public key to the subject name by CA u l Guarantees about uniqueness of name u l CRLs, OCSP, ? ? ? After path validation, relying party can use subject name in place of key u l CAs somehow have to agree on part of name space CA also responsible for certificate revocation u l Plus some other stuff Issuer becomes “X. 509” Expensive to do all of this correctly [email protected] anl. go ATI 2004: Grid Security 5

Need for On-line Certificate Revocation Checking l “Real” deployments need real-time, on-line certificate revocation Need for On-line Certificate Revocation Checking l “Real” deployments need real-time, on-line certificate revocation checking Business needs to know if a key is compromised u Issuance of CRLs not frequent enough u Off-line PKI turns out to be just a dream… u Deployment no different from Kerberos-like system u l Any real-time, mission critical, on-line system is expensive [email protected] anl. go ATI 2004: Grid Security 6

Client 1. Exchange of Certs/Public-Keys Challenge/Response Proof of Private Key Possession (there should be Client 1. Exchange of Certs/Public-Keys Challenge/Response Proof of Private Key Possession (there should be an equivalent authentication procedure for the client) Server 2. Validate CA-Chain 3. Check Certificate Revocation in real-time Public Key Authentication (on-line PKI) Online Certificate Status Protocol (OCSP) Server [email protected] anl. go ATI 2004: Grid Security 7

Key => Subject => user. Id + Attributes l (almost) nobody uses DN u Key => Subject => user. Id + Attributes l (almost) nobody uses DN u u l Plus… any serious application needs user attributes u l l Not a very friendly format Already other identifiers in place customer. Id, SS#, drivers-license, ? ? ? Privacy considerations Etc. , etc. Group membership, roles, clearance levels, credit card numbers/limits, address, etc. Real-time, on-line lookup of user. Id + attributes Equivalent “vetting” or RA-procedure to map subject to user. Id+attributes u Differentiate the Bills from the Williams from the William III…. [email protected] anl. go ATI 2004: Grid Security 8

1. Authentication Protocol Client 2. Check validity of Authentication Server 6. Business Logic uses 1. Authentication Protocol Client 2. Check validity of Authentication Server 6. Business Logic uses all kinds of attributes (NOT Authentication. Id) 4. Authentication "Id" 3. Authentication Result Authentication Server [email protected] anl. go Real-World "Authentication” always includes Attribute Acquisition ATI 2004: Grid Security 5. Attributes (groups/roles, access/audit-Id) Attribute Server 9

Central Path Validation Service (CPVS) l l l Path validation is complicated, error-prone, expensive, Central Path Validation Service (CPVS) l l l Path validation is complicated, error-prone, expensive, black magic, … Centralize its function as a “CPVS” Service Maybe require registration first u u u l All other services do “key-only” authentication u u l Users authenticate with certificate Service performs path validation Registers/caches results Query CPVS for validation (+ user. Id/attributes) (Redirection protocol for those that forgot to register first…) (XKMS protocol could be used for this…) [email protected] anl. go ATI 2004: Grid Security 10

1. Exchange of Public-Keys Challenge/Response Proof of Private Key Possession Client 0. Register certificates 1. Exchange of Public-Keys Challenge/Response Proof of Private Key Possession Client 0. Register certificates Server 2. Check key validity 3. Return relevant attributes Online Central Path Validation Service Check certificate revocations/validity [email protected] anl. go ATI 2004: Grid Security 11

Key => user. Id + Attributes l We have to make real-time, online lookups Key => user. Id + Attributes l We have to make real-time, online lookups anyway… u u l Why do we need the x. 509/subject name? u u l Similar to X. 509 -RA procedure Key revocation/renewal is simple u l Key => user. Id + attributes Elimination of extra indirection Human Resource can “bind” key to user. Id record u l Revocation check user. Id + attributes Update of database record (XKMS could be used for this…) [email protected] anl. go ATI 2004: Grid Security 12

1. Authentication Protocol based on key only Client Server 2. Key Direct mapping of 1. Authentication Protocol based on key only Client Server 2. Key Direct mapping of Key=> Attributes in Corporate Attribute Svc [email protected] anl. go ATI 2004: Grid Security 4. Business Logic uses all kinds of attributes (NOT Authentication. Id) 3. Attributes (groups/roles, access/audit-Id) Attribute Server 13

Key Revocation/Renewal… l l Lost or compromised key – who to tell? Revocation: removal Key Revocation/Renewal… l l Lost or compromised key – who to tell? Revocation: removal of “key => user. Id/attributes” mapping Renewal: new “key => user. Id/attribute” mapping Have to go through (alternative) authentication/registration procedure u l Every registry that maintains mapping must be updated! u u l Not different from x. 509… One registry => no issue Many registries => big issue May not work well for “very” distributed Grid applications [email protected] anl. go ATI 2004: Grid Security 14

Key Revocation & Many Registries l Use a trusted third party as revocation service Key Revocation & Many Registries l Use a trusted third party as revocation service l Only revocation, not key renewal… u Less trust involved l Register both key and revocation service with RAs l Key mapping service should check with revocation svc u l PGP-like… Doesn’t solve renewal… u Still has to be done “in person” [email protected] anl. go ATI 2004: Grid Security 15

Master Key & Proxy Key l Master Key will be ultimate “authority” u u Master Key & Proxy Key l Master Key will be ultimate “authority” u u To To To All empower proxy key revoke proxy key “renew” by empowering new proxy key through assertions l Central revocation service still useful Similar to PGP without email “identity” Similar to proxy-cert without subject l But … user has to store/maintain/manage extra key l l u Arguably incapable to manage any long term key… [email protected] anl. go ATI 2004: Grid Security 16

Non-Identity X. 509 Certificate l Use X. 509 certificate for that one extra level Non-Identity X. 509 Certificate l Use X. 509 certificate for that one extra level of indirection… u l l Subject name just some meaningless unique number “identity vetting” will be left to key => user. Id/attribute registration Use X. 509 standard certificate revocation/renewal methods Registration/revocation/renewal still requires (alternative) authentication with RA/CA u u l l But not for “identity”! Password/mother’s maiden name/? ? ? Or … drivers license, passport, finger print, ? ? ? not for identity vetting but to ensure that the person who registers/revokes/renews is the same person Non-Identity CA much cheaper to operate ESNet opportunity (getting close already…) [email protected] anl. go ATI 2004: Grid Security 17

“Public-Key=Identity” X. 509 Certificate l Existing SSL runtime spoils the fun… u u u “Public-Key=Identity” X. 509 Certificate l Existing SSL runtime spoils the fun… u u u l We could use public key as subject name u l (base 64 of sha 1 digest of key) Need a real CA to vouch for that binding u u u l Requires exchange of real certs Baked-in path validation process Pre-configured list of “trusted” CAs Must be “trusted” to bind the right thing No vetting of identity, though! Much cheaper to deploy. Maybe a nice ESNet service… the PK-CA [email protected] anl. go ATI 2004: Grid Security 18

Conclusion l Alternative “CAs” are moving in u u u l How to establish Conclusion l Alternative “CAs” are moving in u u u l How to establish the “trust” in these heretic-CAs? u l l Equivalent of same-sex marriage, gay Bishops, … Alternative identity assertions u l Absolutely unthinkable five years ago! Use of X. 509 because of revocation not identity… Slowly the X. 509 religion is eroding/enriched… u l Need “language” to express deployment trust levels PKIX standardization of proxy-certs… u l My. Proxy as a “CA”? That stores private keys… KX 509 ESNet’s use of DNs is “interesting”… SAML, LA/WS-Federation… There alternatives to X. 509 deployment… u u Some cheaper, easier to deploy – depends on application XKMS-like tools allow for migration & enables alternatives [email protected] anl. go ATI 2004: Grid Security 19