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- 1. Crypto-Book: An Architecture for Privacy Preserving Online Identities John Maheswaran, David Isaac Wolinsky, Bryan Ford HotNets ’13 (11/22/2013)
- 2. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 3. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 9. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 10. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 11. Privacy and Security Concerns
- 12. Privacy and Security Concerns
- 13. Privacy and Security Concerns
- 14. Privacy and Security Concerns
- 15. Privacy and Security Concerns
- 16. Privacy and Security Concerns
- 17. Privacy and Security Concerns
- 18. Privacy and Security Concerns
- 19. Problem Summary • Increasingly use of cross-site authentication – OAuth, OpenID, Facebook/Twitter/Google+ login • Use social network for online IDs – Convenient, easy to use • Using these IDs brings privacy/tracking risks – Cross-site tracking, browsing history, actions across different sites
- 20. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 21. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 22. Goals • Crypto-Book aims to – Allow users to use social network IDs – Provide better privacy between social network and third party sides
- 25. Crypto-Book Layer Crypto-Book privacy preserving layer Personally identifiable social networking ID
- 26. Crypto-Book Layer Crypto-Book privacy preserving layer Personally identifiable social networking ID
- 27. Crypto-Book Layer Anonymized IDs – one pseudonym per site Crypto-Book privacy preserving layer Personally identifiable social networking ID
- 28. Crypto-Book Layer Crypto-Book privacy preserving layer
- 29. Crypto-Book Layer Crypto-Book privacy preserving layer Not linkable by Facebook, Crypto-Book or by third party sites
- 30. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 31. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 32. Key Assignment • Cross-site authentication often relies on OAuth/OpenID • Crypto-Book fits into OAuth protocol to isolate third party site from social network – Protects cross-site privacy – Assigns key pairs to social network IDs
- 33. OAuth
- 34. OAuth Give me a limited scope OAuth access token
- 35. OAuth Give me a limited scope OAuth access token Issue me an OAuth access token with requested scope
- 36. OAuth Give me a limited scope OAuth access token Issue me an OAuth access token with requested scope
- 37. OAuth Give me a limited scope OAuth access token Issue me an OAuth access token with requested scope
- 38. Key Assignment • To use privacy preserving cryptographic techniques – have to assign public/private keypairs to users • Cloud of key servers with split trust • Clients do not provide own key – Allows us to conscript users into anonymity sets without their knowledge/permission
- 39. OAuth Give me a limited scope OAuth access token Issue me an OAuth access token with requested scope
- 40. OAuth
- 47. Crypto-Book Workflow abuse resistant anonymous 1-to-1 mapping
- 48. Anytrust key servers • An anytrust cloud is: – a decentralized client/server network model – trust there is at least one honest server • Anytrust cloud of key servers – assigns key pairs to each social network user – Run by various privacy advocates e.g. EFF
- 49. Anytrust key servers Key Server Key Server Key Server
- 50. Anytrust key servers Key Server Key Server Key Server
- 51. Anytrust key servers Key Server Key Server Key Server
- 52. Anytrust key servers Key Server Key Server Key Server
- 53. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 54. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 61. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 62. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 63. Balancing Anonymity with Accountability • Need to balance: – Supporting free speech, free expression of opinion – Improving the quality of public discourse. By allowing people to fully hide anonymously, they may do things they would not otherwise • e.g. Wikipedia sock-puppetry, vandalism
- 64. Balancing Anonymity with Accountability • Solution needs to provide both – Anonymity – Accountability • Wikipedia would like to allow users to remain anonymous, but are worried about vandalism – Users need to be anonymous yet accountable
- 69. Linkable Ring Signature (LRS)
- 70. Linkable Ring Signature (LRS)
- 71. Linkable Ring Signature (LRS)
- 72. Linkable Ring Signature (LRS)
- 73. Linkable Ring Signature (LRS) • Created by member of a group of users (each have keys) • Third party can verify: – Some member of the group signed something – If two signatures are by same member • Third party cannot discover – Which specific user created the signature
- 74. Privacy Preserving Crypto Layer • LRS has linkage tag – If a client generates two LRSs, they will have the same linkage tag – Means LRSs can be linked across time • Linkage tag provides accountability – 1-to-1 mapping between Facebook users and anonymized identities
- 76. Crypto-Book Summary abuse resistant anonymous 1-to-1 mapping
- 77. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 78. Talk Overview • The problem – Cross-site Authentication – Social network privacy concerns • Solution – Overview – Key assignment – Conscripting an anonymity set – Anonymous login • Conclusions and future work
- 79. Future Work • Provide OAuth/OpenID API – Integration with more third party sites • Deploy Crypto-Book key servers at various host institutions • Abuse resistant way of using anonymous systems such as Tor • Investigation of anonymity set selection
- 80. Conclusion • Crypto-Book provides privacy preserving online identities – anonymous – abuse resistant • www.crypto-book.com – Demo video – More info, SOSP’13 poster, more talk slides – Link to source code on GitHub