PKI: Public Key Infrastructure What is it, and why should I care? - - PowerPoint PPT Presentation

Wes Hubert Information Services The University of Kansas

PKI: Public Key Infrastructure

What is it, and why should I care?

Conference on Higher Education Computing in Kansas June 3, 2004

Why?

PKI adoption will continue growing to support highly sensitive or regulated business processes. However, the dream

• f 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.

EDUCAUSE Review March/April 2004 PKI: A Technology Whose Time Has Come in Higher Education Mark Franklin, Larry Levine, Denise Anthony, and Robert Brentrup Dartmouth College

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 HECP

InCommon Campus Campus

HECA FBCA

Fd Root CA Agency CA Agency CA

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.

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.

Public Key Infrastructure

(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

PKCS#12 Package X.509 Certificate Public Key Identity Info Other Info CA Signature Private Key

Credential Package

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 Public Key Certificate CA Private Key CA Signing PKCS#12 Generation 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

• bjectives

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 Root CA KU Intermediate CA KU Institutional CA User Certificates KU Personal CA User Certificates Other potential uses

KU Certificate Hierarchy

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

Message Message Digest Compute Transmitted Message (Original message encrypted digest Senders Private Key Encrypted Message Digest Encrypt Senders Cert (Public Key)

(Optional-- may be obtained by other means)

• ptional sender cert)

Signing Process

Message (with encrypted digest) (optional public key cert) Message Digest Compute Encrypted Message Digest (Extract) Senders Cert (Public Key)

Verify through CA Root Cert

Decrypt Message Digest Compare

The message digests match only if 1) Senders private key signed the message 2) The message has not been altered

Signature Verification

Message Generate (Random) Symmetric Key Encrypted Message Encrypt

(Key) (Data)

Encrypt Recipients Cert (Public Key) Encrypted Symmetric Key

(One for each recipient) (Key) (Data)

Transmitted Message (Encrypted message Encrypted key)

Encryption Process

Transmitted Message (Encrypted message Encrypted key) Recipients Private Key Symmetric Key Decrypt Encrypted Symmetric Key

(Key) (Data) Extract

Encrypted Message Message Decrypt

(Key) (Data)

Decryption Process