1. CSE 543 Computer Security: Risks of PKI - Josh Schiffman & Archana Viswanath Ten Risks of PKI: What You're not Being Told about Public Key Infrastructure Joshua Schiffman Archana Viswanath

2. CSE 543 Computer Security: Risks of PKI - Josh Schiffman & Archana Viswanath Computer Security ● Security is a business ○ Especially PKI ● PKI needs business to thrive ○ Buy certificates ○ PKI equipment ● Certificates are the commodity ○ How trustworthy are they?

3. CSE 543 Computer Security: Risks of PKI - Josh Schiffman & Archana Viswanath Categories of Risk ● Security is a chain ○ Only as strong as the weakest link ● We identify three main categories for risk ○ Trust in the Certification Authority (CA) ○ Trust in the encryption keys ○ Trust in the users

4. CSE 543 Computer Security: Risks of PKI - Josh Schiffman & Archana Viswanath Certification Authorities ● PKI requires distribution of public keys ○ Dangerous to send in the clear ● CAs provide certificates binding name to key ○ What makes a CA trusted? ○ What guarantee do we have the certificate is real? Alice CA KBKB Really? This is Bob's public key

5. CSE 543 Computer Security: Risks of PKI - Josh Schiffman & Archana Viswanath Content Authorities ● Certificates contain more than just a key ○ Name / ID ○ DNS for SSL ● Who is authorized to provide this content ○ CAs are not authorities ○ Contrary to many other systems ▶ Business name ▶ Licenses ● Does it always matter? ○ Offers no added encryption

6. CSE 543 Computer Security: Risks of PKI - Josh Schiffman & Archana Viswanath Registration Authority ● Registration Authorities (RA) ○ Authority on the contents ○ Establish secure communication with the CA ● What guarantees are in the RA+CA model? ○ CAs can forge certificates ○ More vectors for attack ○ Authorities physically possessing the CA helps ▶ Breaks some business models

7. CSE 543 Computer Security: Risks of PKI - Josh Schiffman & Archana Viswanath Identifying the Applicant ● Does the CA verify applications? ○ Identity checking ○ Are the credentials easy to obtain? ● Is there private key verification? ○ Possessing the public key for the certificate ▶ Does not prove possession of private key Alice CA KAKA Really? This is my public key

8. CSE 543 Computer Security: Risks of PKI - Josh Schiffman & Archana Viswanath Securing the CA ● CAs don't keep secrets ○ All verification is done with public keys ● Use “root certificates" to vouch for the certificate ○ Self-signed ○ Form a chain of trust ▶ Must end at some ultimately trusted party ● Attackers can inject their own root keys ○ Spoof public keys ● Physically protect the CA