Experiences with Massive PKI Deployment and Usage

1. Experiences with Massive PKI Deployment and Usage Daniel Kouřil, Michal Procházka Masaryk University & CESNET Security and Protection of Information 2009

2. Public Key Infrastructure • Asymetric cryptography • Each user and service owns key-pair • X.509 digital certificates • PGP not suitable • Certification Authority (CA) • Network of Registration Authorities (RA) • Relying parties

3. Distributed environments • Ithanet project • Network for medical research in Mediterranean countries • Users were physicians with little knowledge about computers • Grid infrastructure • Facilitates collaborations, resource sharing • support of research • Basic services provided by grid operator • Easy establishment of secure communication

4. PKI in large-scale environment • PKI is good candidate for authN in large infrastructures • Scalability • Several aspects to be considered and addressed • Operators • Users • General PKI not tied with applications

5. Operating PKI • CA establishment is not technical problem • Building trust is crucial • Many administrative problems • Proper applicants authentication • Protection of signing keys • Proper revocation requests handling • Long-term support • Incident resolution cooperation • … • CAs publish their policies

6. International Grid Trust Federation • Easing orientation for relaying parties • CA managers, identity providers, large relying parties involved • IGTF builds a federation of „trusted“ CAs • approving procedures and minimal requirements • reviews the CA policies (CP/CPS) • Flat model – no root IGTF CA • Unified name space for subject names • User is uniquely identified by their subject name

7. Revocation checks • Revocation is a must • Often neglected by administrators or applications • It‘s impossible to check CRLs with Firefox • Certification Revocation Lists (CRLs) • Online Certificate Status Protocol (OCSP) • Overhead • Latency penalty for online checks • Large amount of data represented by aggregated CRLs transfers

8. Obtaining certificates • The process consists of two phases • Generating key-pair • Identity vetting at RA • Crucial for users‘ perception • Crucial for security of credentials

9. Online CAs • Normal web page with simple form • Registration is done first • Browser is key component • Perform cryptographic operations • Communicates with CA • Receives and stores new certificate • New requirements • Signing machine of CA is exposed • Trust in browser

10. Online CAs in Identity Federations • Identity federations leverage existing users management systems • Access to internal systems of institution • Users don‘t need additional credentials to access new services • Online CA connected to federation • No need for personal visits at RA

11. Private Key Protection • Users don‘t protect their private keys • Weak passphrases, file permissions • Can‘t be checked by PKI operators • Ideally not handled directly by users – transparent PKI • Key repositories • Specialized service maintaining keys for users • Smart cards • User support is difficult in general PKI

12. Conclusions • Several aspects to address to operate secure PKI • Established set of trusted CAs available • General CAs, not tied with a particular application • Keep users away from their private keys • :-)

13. Backup slides

14. Single Sign-On • User authenticates just once • Proxy certificate • Issued by user • Only short-lived • Standard X.509 short-lived certificates • Issued by an on-line CA • Can be obtained automatically after login