PKI: Public Key Infrastructure What is it, and why should I care? Conference on Higher Education Computing in Kansas June 3, 2004 Wes Hubert Information Services The University of Kansas
Why?
PKI adoption will continue growing to support highly sensitive or regulated business processes. However, the dream of using it for general-purpose authentication and ubiquitous digital signatures is still several years in the future and not a certainty. Public Key Infrastructure: Making Progress, But Many Challenges Remain Dan Blum and Gerry Gebel, Burton Group March 2003 ECAR report
PKI adoption hurdles are lower than ever, and the benefits are greater than ever. The time has come to stop studying and testing and take the plunge. PKI: A Technology Whose Time Has Come in Higher Education Mark Franklin, Larry Levine, Denise Anthony, and Robert Brentrup Dartmouth College EDUCAUSE Review March/April 2004
You should know enough about PKI to determine which view applies to your current situation.
Benefits Strong authentication HIPAA, FERPA, etc. Protection from sniffing attacks S/MIME secure email Signing, encryption Work with other PKI developments Inter-university use of PKI Kansas government PKI use Grant signing requirements
Hurdles Certification Authority Issues Outsource, Buy, or Build? Key/Certificate Management Policy Development Registration of users (vetting) Finding compatible applications User key management
Common PKI Use Establishing SSL Connections Authenticates web server to browser Uses CA root built into browser University buys certificates from CA Protection is only for data transfer Does not authenticate user Does not authenticate a specific service User-level: Individual CA Certs/Keys
Non-PKI Keys/Certificates Argus Server Authentication Certificates for server-to-server authentication Locally generated keys and certs No direct user involvement Argus User Authentication NOT certificate-based User-level: PGP, GPG, SSH
Higher Education Organizations for PKI NMI-EDIT NSF Middleware Initiative Enterprise and Desktop Integration Technologies Members EDUCAUSE Internet 2 SURA (SE Univ Research Assoc) HEPKI-TAG Coordinates many PKI developments
Higher Education Initiatives USHER US Higher Education Root Follow-on to CREN as CA InCommon Shibboleth Federation CA Signs Institutional Shib Certs HEBCA Higher Education Bridge Certification Authority
USHER Certificates Low Few constraints on campus operations Suitable for many campus needs Good for learning Basic CP places more constraints on use HEBCA peering Both will issue only institutional certs
HEBCA Trust HEBCA FBCA InCommon HECP Fd Root CA HECA Agency CA Agency CA Campus Campus
Kansas Government PKI Distributed across several agencies Information Technology Executive Council (ITEC) Responsible for Kansas Certificate Policy Office of Secretary of State (SOS) Responsible for CA services contract Information Network of Kansas (INK) Responsible for KS Info Consortium contract KIC manages official state web site www.accesskansas.org
Kansas Government PKI Distributed across several agencies General state PKI information online at: http://da.state.ks.us/itab/pkimain.htm Agencies using service act as Local Registration Authority Current end-entity certs $40/year
Kansas Government PKI Agencies using PKI State Treasurer s Office The Vault Extranet Department of Revenue E-Lein Department of Transportation
Kansas Government PKI Identity Management Security Levels Level 1 Virtual Vetting (no physical presence) Level 2 Physical Vetting; LRA Level 3, 4 Not yet issuing
Kansas Statutes Chapter 16. Contracts and Promises Article 16. Electronic Transactions Electronic Signature [16-1602(i)] Digital Signature [16-1602(e)] If a law requires a signature, an electronic signature satisfies the law. [16-1607(d)] http://www.kslegislature.org/cgi-bin/ statutes/index.cgi/
Electronic Signature... an electronic sound, symbol or process attached to or logically associated with a record and executed or adopted by a person with the intent to sign the record.
Digital Signature... a type of electronic signature consisting of a transformation of an electronic message using an asymmetric crypto system such that a person having the initial message and the signer's public key can accurately determine whether:!!! (1)! The transformation was created using the private key that corresponds to the signer's public key; and!!! (2)! the initial message has not been altered since the transformation was made.
Given a choice between security and convenience, users will choose convenience.
Public Key Infrastructure A system of CAs (and, optionally, RAs and other supporting servers and agents) that perform some set of certificate management, archive management, key management, and token management functions for a community of users in an application of asymmetric cryptography. (RFC2828 Definition)
Traditional Cryptography Symmetric Same key that encrypts, decrypts Key is always secret Problems Exchanging key with trusted parties Same key gives everyone access Access includes ability to modify
Traditional Cryptography DES (Data Encryption Standard) IBM, NIST, NSA 1970s 56-bit key Triple DES, 112-bit effective key size AES (Advanced Encryption Standard) Rijndael 128/192/256-bit key sizes
Public Key Cryptography Diffie-Hellman 1976 Asymmetric Two keys: one private, one public Each decrypts what other encrypts Problems Much slower than symmetric Key management
Public Keys Provide Confidentiality Protection again unauthorized access Integrity Protection against unauthorized changes Authentication Verification of an identity Nonrepudiation Cannot deny private key was used
Key Management Generating Keys Authenticating Public Keys Distributing Keys
Generating Keys Keys are generated in pairs Private/Public Keeping private keys secret Ideally no one but owner ever has key Problems convenience escrow recovery
Authenticating Public Keys X.509 Certificates Bind public keys to identity information Contents Include Version Number Public Key Owner s Name Initial / Final Dates Valid... other information... Signed by issuing CA
Digital Credentials Private Key For exclusive use of owner MUST be kept secure Public Key Certificate Available to everyone Links key with owner s identity Trust must be established somehow
Distributing Credentials PKCS#12 Standard for secure transportation of user identity information Wraps data in password-protected object Content can include Keys Certificates Passwords
Credential Package PKCS#12 Package Private Key X.509 Certificate Public Key Identity Info Other Info CA Signature
Certificate Management Distribution User to user (e.g. email) LDAP directories Revoking Certificates Certificate Revocation Lists (CRL) Online Cert Status Protocol (OCSP) Keys and Certificates are not the same Certificates not used for private keys
Credential Generation Key Generation Private Key Public Key ID Information Certificate Signing Request CA Private Key CA Signing PKCS#12 Generation Public Key Certificate PKCS#12 Object Package
Public Key Infrastructure Solves some problems of public keys Establishing owner s identity Defining validity dates, uses Based on trusted third party Signing may be through multiple levels CA cert may sign other CA certs Must end at trusted root CA
Certification Authority Functions Register Users Directly or through Registration Authority Issue Public Key Certificates Revoke Certificates Publish revocation information Archive Key and Certificate Data Retrieve archives when appropriate May or may not ever have user private key
Policies and Procedures Certificate Policy Statement Broad specification of policy objectives Accepted by CA & relying party Certification Practices Statement Detailed practices for issuing certificates Certificate lifetime, revocation, etc.
KU as Certification Authority Strong authentication for campus services Registration already done via Registrar & Human Resources A natural extension of current I/A/A activity KU Online ID, AMS, Argus, LDAP Policy framework: EDUCAUSE, I2 Build on open source foundation
KU Certificate Hierarchy KU Root CA KU Intermediate CA KU Personal CA KU Institutional CA Other potential uses User Certificates User Certificates
KU Root Certificate Available on web at: https://www.ku.edu/kuca Currently root/anchor certificate Must be installed into client system Plan USHER-based path in future Corresponding private key: Used only to sign Intermediate CA Cert Now stored only on encrypted CD
KU Digital Credential Process Action Initiated by Location Test Request User Web Approval CA Server ID Request User Web Generation CA Offline CA Notification CA Email Retrieval User Web Installation User User s PC Use User Application
S/Mime Email Normal Email is like a postcard Message encryption seals the envelope Digital signature adds unique sealing wax stamp
Signing Process Message Sender!s Private Key Sender!s Cert (Public Key) Compute (Optional-- may be obtained by other means) Message Digest Encrypt Encrypted Message Digest Transmitted Message (Original message encrypted digest optional sender cert)
Signature Verification Message (with encrypted digest) (optional public key cert) Sender!s Cert (Public Key) (Extract) Encrypted Message Digest Verify through CA Root Cert Compute Decrypt Message Digest Message Digest Compare The message digests match only if 1) Sender!s private key signed the message 2) The message has not been altered
Encryption Process Message Generate (Random) Symmetric Key Recipient!s Cert (Public Key) (Data) (Key) (Data) (Key) Encrypt Encrypt Encrypted Message Encrypted Symmetric Key (One for each recipient) Transmitted Message (Encrypted message Encrypted key)
Decryption Process Transmitted Message (Encrypted message Encrypted key) Recipient!s Private Key Extract Encrypted Symmetric Key (Data) (Key) Encrypted Message Decrypt Symmetric Key (Data) (Key) Decrypt Message