Zero Knowledge Architectures for mobile Applications

#iosdev #security #trust #keys

- why we need ZKA
- what is ZKA, what are parts of ZKA system
- messaging, auth, data: how to use ZKA in these usecases
- ZKA data management example
- implementation details
- other possible usecases
- recap

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If you can't tap on the link inside slides, please open as pdf (button on the right).

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With intensifying threat access, snooping governments and insecure-internet-of-everything, the importance of zero-knowledge application architectures and end-to-end trust, for things more complicated than simple messaging, becomes more and more obvious for the app developers.

We will talk about real-world problems that ZKA fights against, learn typical cryptographic designs and progress in different spheres of ZKA. We will find out how to make data sharing, user collaboration on data in the cloud with your app provably secure.

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text:
https://medium.com/@vixentael/zero-knowledge-architectures-for-mobile-applications-b00a231fda75

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video from MobiConf17
https://youtu.be/79iqPsPc6ZE

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Links to follow:

Hermes
https://github.com/cossacklabs/hermes-core

Anatomy of a Zero-Knowledge Web Application, 2007
https://clipperz.is/blog/2007/08/24/anatomy_zero_knowledge_web_application/

Zero Knowledge Protocols Without Magic
https://www.cossacklabs.com/zero-knowledge-protocols-without-magic.html

Why We Develop Zero Knowledge Software
https://brainsware.at/blog/9-zero-knowledge-saas

Keybase launches encrypted git
https://keybase.io/blog/encrypted-git-for-everyone

Why We Will No Longer Use the Phrase Zero Knowledge to Describe Our Software
https://spideroak.com/articles/why-we-will-no-longer-use-the-phrase-zero-
knowledge-to-describe-our-software/

Explain Like I’m 5: End-to-end Encryption
https://medium.com/@cossacklabs/eli5-end-to-end-encryption-ae46821db74f

Explain Like I’m 5: Zero Knowledge Proof
https://hackernoon.com/eli5-zero-knowledge-proof-78a276db9eff

Zero Knowledge Proofs: An illustrated primer
https://blog.cryptographyengineering.com/2014/11/27/zero-knowledge-proofs-illustrated-primer/

Transcript

1. ZERO KNOWLEDGE ARCHITECTURES for mobile applications
2. @vixentael Mobile Tech Lead Feel free to reach me with any mobile security questions. I do check my inbox :)
3. Let’s play a game
4. Sensitive data – ? @vixentael
5. E2EE – ? @vixentael
6. GDPR – ? @vixentael
7. GDPR – ? Equifax – ? @vixentael
8. #mobiconf @vixentael
9. Where we are
10. We have sensitive data @vixentael
11. We have sensitive data We put it to the “cloud” @vixentael
12. We put it to the “cloud”
13. We put it to the “cloud” Everything runs on smbd’s software, on smbd’s computer, is maintained by someone else @vixentael
14. We have sensitive data We put it to the “cloud” Everything runs on smbd’s software, on smbd’s computer, is maintained by someone else @vixentael
15. Do we trust them? @vixentael
16. Do we trust them? Do we want to trust them? @vixentael
17. – NO.
18. We don’t want. @vixentael
19. to know how secure cloud is We don’t want @vixentael
20. to trust other ppl’s software, computers, and maintenance practices - to know how secure cloud is We don’t want @vixentael
21. to think about sensitive data leakage - to trust other people’s software, computers, and maintenance practices - to know how secure cloud is We don’t want @vixentael
22. - to think about sensitive data leakage - to trust other people’s software, computers, and maintenance practices - to know how secure cloud is We don’t want @vixentael
24. We don’t want to share sensitive data.
25. We don’t want to share sensitive data, but we must
26. medical records credit history ? } @vixentael
27. your data, managed by someone medical records credit history = @vixentael
28. – Need control.
29. Control access to the sensitive data during storing and sharing. @vixentael
30. How? Control access to the sensitive data during storing and sharing. @vixentael
31. – Encryption.
32. Messaging End-to-End Encryption @vixentael
33. Authentication Zero Knowledge Proof https://www.cossacklabs.com/zero- knowledge-protocols-without-magic.html @vixentael
34. Data ??? - store encrypted - share with others - manage access to parties @vixentael
35. – Zero Knowledge Architectures
36. ZKA is a design principle that enables software to provide services over protected client data without having an unencrypted access to it. @vixentael
37. e2ee clients ZKA includes @vixentael
38. e2ee clients all operations are on encrypted data: – control access to data from different users – CRUD – search (in encrypted data) ZKA includes @vixentael
39. ZKA is already solved for specific use-cases or in a naive ways @vixentael
40. Sharing encrypted data: naive approach – duplications – key management problems @vixentael
41. give access to certain blocks of data to exact users https://github.com/cossacklabs/ hermes-core Our take @vixentael
42. - Why me?
43. ZKA relies on trust to the client @vixentael
44. ZKA relies on trust to the client Mobile runs code safely* @vixentael
45. ZKA relies on trust to the client Mobile stores keys safely* Mobile runs code safely* @vixentael
46. Mobile stores keys safely* ZKA relies on trust to the client Mobile runs code safely* Mobile is a good client Brent @vixentael
47. – Meanwhile in the real world…
49. { "personal_data": { "name": "Cat", "surname": "Black", "age": 25, "home_address": "large box in living room", "birth_date": "01/04/1992" }, "credit_rating": 8.7, "transactions": [{ "operation": "credit", "bank": "CatBank1", "amount": "2000", "currency": "eur", "date": "02/10/2017" }, { "operation": "credit", "bank": "CatBank2", "amount": "500", "currency": "eur", "date": "14/02/2015" } ] } @vixentael
50. { "personal_data": { "name": "Cat", "surname": "Black", "age": 25, "home_address": "large box in living room", "birth_date": "01/04/1992" }, "credit_rating": 8.7, "transactions": [{ "operation": "credit", "bank": "CatBank1", "amount": "2000", "currency": "eur", "date": "02/10/2017" }, { "operation": "credit", "bank": "CatBank2", "amount": "500", "currency": "eur", "date": "14/02/2015" } ] } personal data @vixentael
51. protected data { "personal_data": { "name": "Cat", "surname": "Black", "age": 25, "home_address": "large box in living room", "birth_date": "01/04/1992" }, "credit_rating": 8.7, "transactions": [{ "operation": "credit", "bank": "CatBank1", "amount": "2000", "currency": "eur", "date": "02/10/2017" }, { "operation": "credit", "bank": "CatBank2", "amount": "500", "currency": "eur", "date": "14/02/2015" } ] } @vixentael
52. { "personal_data": { "name": "Cat", "surname": "Black", "age": 25, "home_address": "large box in living room", "birth_date": "01/04/1992" }, "credit_rating": 8.7, "transactions": [{ "operation": "credit", "bank": "CatBank1", "amount": "2000", "currency": "eur", "date": "02/10/2017" }, { "operation": "credit", "bank": "CatBank2", "amount": "500", "currency": "eur", "date": "14/02/2015" } ] } really-really protected data @vixentael
53. you bank credit bureau @vixentael
54. you bank credit bureau @vixentael
55. you bank credit bureau @vixentael
56. you bank credit bureau @vixentael
57. you bank credit bureau @vixentael
58. you bank credit bureau @vixentael
59. you bank credit bureau what could possibly go wrong? @vixentael
60. leakage from – your data is available everywhere Risks @vixentael
61. leakage from – your data is available everywhere Risks encrypt data with one shared ? leak one key – leak everything @vixentael
62. B&B can accumulate extra data about you. Risks @vixentael
63. B&B can judge you by things you haven’t done. Risks @vixentael
64. B&B can record requests about people they don’t know. Risks @vixentael
65. How ZKA can help?
66. { "personal_data": { "name": "Cat", "surname": "Black", "age": 25, "home_address": "large box in living room", "birth_date": "01/04/1992" }, "credit_rating": 8.7, "transactions": [{ "operation": "credit", "bank": "CatBank1", "amount": "2000", "currency": "eur", "date": "02/10/2017" }, { "operation": "credit", "bank": "CatBank2", "amount": "500", "currency": "eur", "date": "14/02/2015" } ] } RW RO RO, customer verification RW @vixentael
67. access to data blocks encrypted controlled by owner @vixentael
68. stores encrypted updates only credit score owns, controls access RW only their transactions access revoked @vixentael
69. - Key wrapping storage keys user keys How to build it? @vixentael blocks
70. - Key wrapping - Manage privileges How to build it? @vixentael
71. - Key wrapping - Manage privileges - Control requests How to build it? @vixentael
72. - Key wrapping - Manage privileges - Control requests - Mitigate remaining attacks How to build it? @vixentael
73. leakage → privileges → replay → other? → Mitigating the risks: @vixentael
74. leakage → it’s encrypted privileges → replay → other? → Mitigating the risks: @vixentael
75. leakage → it’s encrypted privileges → it’s encrypted replay → other? → Mitigating the risks: @vixentael
76. leakage → it’s encrypted privileges → it’s encrypted replay → ZKP (it’s encrypted ;) other? → Mitigating the risks: @vixentael
77. leakage → it’s encrypted privileges → it’s encrypted replay → ZKP (it’s encrypted ;) other? → tiny attack surface Mitigating the risks: @vixentael
78. ZKA elsewhere
79. shared audit logs complex docs, spreadsheets config files file system document store protection @vixentael
80. Is it difficult to implement?
81. Signal https://github.com/WhisperSystems/ SignalProtocolKit/blob/master/AxolotlKit/Classes/ Sessions/SessionBuilder.m @vixentael
82. Swift Alps Demo https://github.com/cossacklabs/theswiftalpsdemo/ blob/master/ios-project/SwiftAlpsSecDemo/ SwiftAlpsSecDemo/SessionDemo.swift github.com/ cossacklabs/themis @vixentael
83. Hermes github.com/cossacklabs/ hermes-core ODING IN PROGRESS CODING IN PROG @vixentael
84. Other examples https://tahoe-lafs.org/trac/tahoe-lafs The Least-Authority File Store https://tresorit.com/zerokit ZeroKit from Tresorit @vixentael
85. Recap
86. 1. We know a lot about data protection and peer-to-peer communication. 2. Collaborating on data exposes more advanced risks. One key is not enough. 3. ZKA helps against advanced risks. 4. Sooner or later, everything will be collaborative. 5. Learn ZKA in advance! @vixentael
87. Links 1 https://clipperz.is/blog/2007/08/24/anatomy_zero_knowledge_web_application/ Anatomy of a Zero-Knowledge Web Application, 2007 https://www.cossacklabs.com/zero-knowledge-protocols-without-magic.html Zero Knowledge Protocols Without Magic https://brainsware.at/blog/9-zero-knowledge-saas Why We Develop Zero Knowledge Software
88. Links 2 https://spideroak.com/articles/why-we-will-no-longer-use-the-phrase-zero- knowledge-to-describe-our-software/ Why We Will No Longer Use the Phrase Zero Knowledge to Describe Our Software https://medium.com/@cossacklabs/eli5-end-to-end-encryption-ae46821db74f Explain Like I’m 5: End-to-end Encryption https://keybase.io/blog/encrypted-git-for-everyone Keybase launches encrypted git
89. My other security slides https://github.com/ vixentael/my-talks
90. @vixentael Mobile Tech Lead Feel free to reach me with any mobile security questions. I do check my inbox :)
91. Image credits www.flaticon.com freepik, linector, switficons, pixelperfect, smashicons Authors: