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PKI and LOA

PKI and LOA. Establishing a Basis for Trust. David L. Wasley. PKI Deployment Forum April 2008. Outline. Level of Assurance generally PKI LoA InCommon Identity Assurance Profiles PKI and Federated Identity. Level of Assurance generally.

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PKI and LOA

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  1. PKI and LOA • Establishing a Basis for Trust David L. Wasley PKI Deployment Forum April 2008

  2. Outline • Level of Assurance generally • PKI LoA • InCommon Identity Assurance Profiles • PKI and Federated Identity

  3. Level of Assurance generally • Intent is to give Relying Party confidence in information it receives about a Subject • Trust is based on many factors • No trust is perfect • Relying Parties must do risk analysis • Build on existing conventions • Mechanism must be practical • Excessive complexity won’t be acceptable

  4. PKI LoA • Based on Federal PKI model • One CP • 4 levels of trust (plus “test”) • CP OIDs used to convey level • Allowed for mapping between PKI domains • Copied by other PKIs • Pharma, aerospace, HEBCA, … • “Meets or exceeds” implies asymmetry

  5. PKI LoA factors include… • Identity proofing process • In-person or remote, one or more primary documents, degree of verification • Key generation and length • Software vs. hardware key protection • Key usage, multiple keys • Validity period and re-key requirements

  6. PKI LoA factors (cont.) • Certificate delivery • Whether private keys are escrowed • Revocation requirements • Operation and management of CA • Personnel controls • Physical and logical controls • System software and hardware controls • Change management, disaster recovery, …

  7. Implementation • Trust within a PKI derives from root (TA) • Each CA is audited against CP/CPS • Relying Parties know which TA(s) to trust • A Bridge CA might be able to map trust • May be asymmetrical! • What’s in the cert is all RP learns about Subject • May be more than it should know • Note however the X.509 subjectInfoAccess field !

  8. PKI strength & weakness • Supports more than “identity” • Signing, data integrity, etc… • Hardware tokens are very strong credentials • Certificates are awkward to update • Software storage might be compromised • Esp. if cert can be exported w/private key • Re-authentication may be impossible • A pitfall of SSO generally …

  9. Identity Federation and LoA • Federated IT environments separate identity and access management • AuthN binds an identifier to a physical person • Necessary information about that person is given to access management systems separately • IdP issues credentials & stores attributes • Id proofing attempts to ensure uniqueness • Id attributes come from authoritative sources • Assurance doesn’t have to be hierarchical • Different “profiles” for different use cases

  10. Identity Model • Identity is the set of information about a person • Unique attributes, e.g., biometric, U.S. President, ... • Group attributes, e.g., student, male, Joe Smith, ... • Pseudonymous, e.g., the same person as before • Three parties involved • Identity Subject is who wants to claim an ID • Relying Party, e.g. Service Provider, trusts identity information received from an Identity Provider • Identity Provider supports identity Subjects by maintaining a database of reliable ID data • Each party must trust the others

  11. Identity Model (cont.) • Digital credential is bound to a physical person • May, but need not, contain some identity information • Several credential technologies may be used • Binding achieved through a registration process • RA process finds existing record or creates a new one • Credential S/N is index to Identity Mgmt DB • Credential S/N need not be same as Subject identifier • Relying Party uses ID information as part of decision about access to services or resources • Is Provider’s assertion of identity good enough?

  12. Identity Assurance projects • NIST 800-63-1 • Federal eAuthentication • See also M0404, HSPD-12 and NIST FIPS 201 • Liberty Alliance Identity Assurance Framework • RealID “Final Rule” • FBI Biometrics Database • InCommon Identity Assurance Profiles • “Bronze”, “Silver”, ...

  13. InCommon Identity Assurance Profiles • Now in DRAFT and may change … • Structured sets of requirements intended to satisfy management of access to general classes of resources • Not necessarily hierarchical • Hopefully limited in number(!) • First two defined to be comparable to eAuth • “Bronze” >= eAuth level 1 • “Silver” >= eAuth level 2 (~= FPKI Basic?)

  14. Identity Assurance Framework • Business, Policy and Operational Factors • Registration and Identity Proofing • Digital Electronic Credential Technology • Digital Electronic Credential Issuance and Management • Security and Management of Authentication Events • Identity Information Management • Identity Assertion and Content • Technical Environment

  15. InCommon “Silver” Profile • Business, Policy and Operational Factors • Established legal entity • • Designated authority for IdMS & IdP • • General Disclosures to identity Subjects • • Documentation of policies & practices • Appropriate staffing • Subcontracts • Helpdesk • Audit of IdMS operations • • Risk Management plan • Logging of operation events

  16. InCommon “Silver” (cont.) • Registration and Identity Proofing • Identity Verification Process disclosure • Retain records of Id documents • And one or more of: • Existing relationship with the organization • In-person proofing • Remote proofing • Digital Electronic Credential Technology • Unique credential identifier • • Subject modifiable shared secret • • Strong resistance to guessing shared secret *

  17. InCommon “Silver” (cont.) • Credential Issuance and Management • Unique Subject record identifier • • Credential status • • Confirmation of delivery • Credential verification at time of use • Suspected credential compromise (†) • Credential revocation † indicates an InCommon variant from the NIST recommendations

  18. InCommon “Silver” (cont.) • Security and Management of Authentication Events • End-to-end secure communications * • Proof that Subject has control of credential • • Session token authentication • • Secure stored secrets • • Restricted use of secrets • Mitigate risk of sharing credentials • Threat protection * • Authentication protocols *

  19. InCommon “Silver” (cont.) • Identity Information Management • Identity status management • Identity Assertion and Content • eduPerson attributes • (†) • Identity Assertion Qualifier • (†) • Cryptographic security • • Technical Environment • Configuration Management • Network Security • Physical Security • Continuity of Operations (†)

  20. Implementation • Notify InCommon of intention to qualify • Assessment by independent (internal) auditor • Auditor writes summary letter for InCommon • Execute Participation Agreement Addendum • InCommon adds Identity Assurance Designator(s) to IdP directory data • IdP then may include IAQ(s) in assertions • Is responsible to ensure they are appropriate • Technical implementation yet to be determined

  21. Use of InCommon IAQs • IAQ represents a profile, not a “level” • A given IdP can support multiple profiles • IdP may assert InCommon IAQ(s) only if assigned to it by InCommon • Identity assertion may contain multiple IAQs • E.g., “Bronze” or both “Silver” and “Bronze” • Avoids implying hierarchy and allows for additions with minimal disruption • Relying Party looks for IAQ(s) it will accept

  22. PKI & Federation • Similar trust models • Trusted authority vets adherence to profiles • Registration authority vets Subject identity • Assurance included in cert or assertion • Credential compromise is dealt with • Threats are mitigated • Linking federations is like PKI bridging

  23. PKI plus Federation • The best of both worlds! • PKI provides strong local authentication • Federation provides rich, flexible identity • Also solves the TA problem • PKI also supports S/MIME, signature, etc.

  24. LoA is new & evolving • How many profiles are needed? • Should attributes have separate LoA? • Must all attributes have the same LoA? • How can we inter-federate and map LoA? • Can anyone use SAML authNContext? • Etc. etc. etc…

  25. Further Information • InCommon Identity Assurance Profiles • David Wasley <dlwasley@earthlink.net> • NIST 800-63 • http://csrc.nist.gov/publications/PubsSPs.html • Liberty Alliance Identity Assurance Framework • http://www.projectliberty.org/liberty/strategic_initiatives/identity_assurance • RealID • http://www.dhs.gov/xprevprot/programs/gc_1200062053842.sht • FBI biometrics database • http://www.washingtonpost.com/wp-dyn/content/article/2007/12/21/AR2007122102544.html

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