EPID is a digital signature scheme that allows for anonymity and privacy. It uses a single public key that corresponds to multiple private keys, so the private key used to generate a signature cannot be identified. EPID signatures can be verified using the group public key. EPID provides granular revocation mechanisms and has been shipping since 2008 in Intel processors. It is used for technologies like Intel Insider, Intel TXT, Intel IPT and Intel SGX.

1. Introduction to Intel EPID

2. 2
Intel Enhanced Privacy ID
EPID is a digital signature scheme with special properties:
• Single public key corresponds to multiple private keys
• Each unique private key can be used to generate a signature
• Signature can be verified using the group public key
• No one can tell which private key was used to generate a signature
RSA/DSA/
ECDSA
EPID
Pub-Key
Pvt-Key
Pvt-Key 1
Pub-Key
Pvt-Key 2 Pvt-Key 3

3. 3
Intel Enhanced Privacy ID
International Standard
• ISO/IEC 20008/20009 & TCG
• Privacy Preserving Anonymous Attestation
• RAND-Z licensing
Mature Technology
• Shipping since 2008
• Xeon, Core 2011
• Atom, 2014 → sub-Atom
• 2.4B Keys since 2008
Utilization of EPID
• Intel Insider (Digital Rights Management)
• Intel Trusted Execution Technology (Intel TXT)
• Intel Identity Protection Technology (Intel IPT)
• Intel Software Guard Extensions (Intel SGX)
Intel is Enabling the Industry on EPID

4. 4
Anonymity in practice
Anonymous GPS data
Likely there is a
traffic jam here:
49°26'33.3"N
11°05'14.0"E

5. 5
Linkability
Every 5 min
Thanks to full privacy EPID gives us we don’t even
know about messages coming from the same
source.
Sometimes that’s a problem...
EPID offers a parameter called basename to control
linkability.

6. 6
Revocation
Position:
38472384 N
23122333 E
EPID provides granular revocation mechanisms:
• Group Revocation (GroupRL)
• Private Key Based Revocation (PrivRL)
• Signature Based Revocation (SigRL)
• Verifier Blacklist Revocation
!?

7. 7
EPID Verification Service
• Publicly available web service
• Way to use EPID without diving into SDK, saves you from:
• Revocation list handling
• Key management
• Converts EPID signatures to standard ECDSA

8. 8
EPID Verification Service
Device
3rd party service
EPID Verification Service
ECDSA Proof
EPID Signature
ECDSA Proof

9. 9
Materials available for Hackathon
• EPID SDK:
• Sources
• Documentation
• Examples
• Precompiled libraries
• Simplified examples in C
• Locally hosted version of EPID Verification service
• EPID Cheatsheet