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

--------------------------------------

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

--------------------------------------

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.

--------------------------------------

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

--------------------------------------

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

--------------------------------------

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
   

   View Slide

2. @vixentael Mobile
   Tech Lead
   Feel free to reach me with any
   mobile security questions.
   I do check my inbox :)
   

   View Slide

3. Let’s play a game
   

   View Slide

4. Sensitive data – ?
   @vixentael
   

   View Slide

5. E2EE – ?
   @vixentael
   

   View Slide

6. GDPR – ?
   @vixentael
   

   View Slide

7. GDPR – ?
   Equifax – ?
   @vixentael
   

   View Slide

8. #mobiconf @vixentael
   

   View Slide

9. Where we are
   

   View Slide

10. We have sensitive data
    @vixentael
    

    View Slide

11. We have sensitive data
    We put it to the “cloud”
    @vixentael
    

    View Slide

12. We put it to the “cloud”
    

    View Slide

13. We put it to the “cloud”
    Everything runs
    on smbd’s software, on smbd’s computer,
    is maintained by someone else
    @vixentael
    

    View Slide

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
    

    View Slide

15. Do we trust them?
    @vixentael
    

    View Slide

16. Do we trust them?
    Do we want to trust them?
    @vixentael
    

    View Slide

17. – NO.
    

    View Slide

18. We don’t want.
    @vixentael
    

    View Slide

19. to know how secure cloud is
    We don’t want
    @vixentael
    

    View Slide

20. to trust other ppl’s software,
    computers, and maintenance
    practices
    - to know how secure cloud is
    We don’t want
    @vixentael
    

    View Slide

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
    

    View Slide

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
    

    View Slide

23. View Slide

24. We don’t want to share
    sensitive data.
    

    View Slide

25. We don’t want to share
    sensitive data,
    but we must
    

    View Slide

26. medical records
    credit history
    ?
    }
    @vixentael
    

    View Slide

27. your data,
    managed
    by someone
    medical records
    credit history
    =
    @vixentael
    

    View Slide

28. – Need control.
    

    View Slide

29. Control access to the sensitive
    data during storing and sharing.
    @vixentael
    

    View Slide

30. How?
    Control access to the sensitive
    data during storing and sharing.
    @vixentael
    

    View Slide

31. – Encryption.
    

    View Slide

32. Messaging End-to-End
    Encryption
    @vixentael
    

    View Slide

33. Authentication Zero Knowledge
    Proof
    https://www.cossacklabs.com/zero-
    knowledge-protocols-without-magic.html
    @vixentael
    

    View Slide

34. Data ???
    - store encrypted
    - share with others
    - manage access to
    parties
    @vixentael
    

    View Slide

35. – Zero Knowledge
    Architectures
    

    View Slide

36. ZKA is a design principle that
    enables software to provide
    services over protected client data
    without having an unencrypted
    access to it.
    @vixentael
    

    View Slide

37. e2ee clients
    ZKA includes
    @vixentael
    

    View Slide

38. e2ee clients
    all operations are on encrypted data:
    – control access to data from different users
    – CRUD
    – search (in encrypted data)
    ZKA includes
    @vixentael
    

    View Slide

39. ZKA is already solved for
    specific use-cases or
    in a naive ways
    @vixentael
    

    View Slide

40. Sharing encrypted data:
    naive approach
    – duplications
    – key management
    problems
    @vixentael
    

    View Slide

41. give access to
    certain blocks of
    data to exact users
    https://github.com/cossacklabs/
    hermes-core
    Our take
    @vixentael
    

    View Slide

42. - Why me?
    

    View Slide

43. ZKA relies on trust to the client
    @vixentael
    

    View Slide

44. ZKA relies on trust to the client
    Mobile runs code safely*
    @vixentael
    

    View Slide

45. ZKA relies on trust to the client
    Mobile stores keys safely*
    Mobile runs code safely*
    @vixentael
    

    View Slide

46. Mobile stores keys safely*
    ZKA relies on trust to the client
    Mobile runs code safely*
    Mobile is a good client Brent
    @vixentael
    

    View Slide

47. – Meanwhile in
    the real world…
    

    View Slide

48. View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

53. you
    bank
    credit
    bureau
    @vixentael
    

    View Slide

54. you
    bank
    credit
    bureau
    @vixentael
    

    View Slide

55. you
    bank
    credit
    bureau
    @vixentael
    

    View Slide

56. you
    bank
    credit
    bureau
    @vixentael
    

    View Slide

57. you
    bank
    credit
    bureau
    @vixentael
    

    View Slide

58. you
    bank
    credit
    bureau
    @vixentael
    

    View Slide

59. you
    bank
    credit
    bureau
    what could possibly go wrong?
    @vixentael
    

    View Slide

60. leakage from –
    your data is available everywhere
    Risks
    @vixentael
    

    View Slide

61. leakage from –
    your data is available everywhere
    Risks
    encrypt data with one shared ?
    leak one key – leak everything
    @vixentael
    

    View Slide

62. B&B can accumulate extra data
    about you.
    Risks
    @vixentael
    

    View Slide

63. B&B can judge you by things
    you haven’t done.
    Risks
    @vixentael
    

    View Slide

64. B&B can record requests about
    people they don’t know.
    Risks
    @vixentael
    

    View Slide

65. How ZKA can help?
    

    View Slide

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
    

    View Slide

67. access to data
    blocks
    encrypted
    controlled by
    owner
    @vixentael
    

    View Slide

68. stores encrypted
    updates only credit score
    owns,
    controls access
    RW only their
    transactions
    access
    revoked
    @vixentael
    

    View Slide

69. - Key wrapping
    storage keys user keys
    How to build it?
    @vixentael
    blocks
    

    View Slide

70. - Key wrapping
    - Manage privileges
    How to build it?
    @vixentael
    

    View Slide

71. - Key wrapping
    - Manage privileges
    - Control requests
    How to build it?
    @vixentael
    

    View Slide

72. - Key wrapping
    - Manage privileges
    - Control requests
    - Mitigate remaining attacks
    How to build it?
    @vixentael
    

    View Slide

73. leakage →
    privileges →
    replay →
    other? →
    Mitigating the risks:
    @vixentael
    

    View Slide

74. leakage → it’s encrypted
    privileges →
    replay →
    other? →
    Mitigating the risks:
    @vixentael
    

    View Slide

75. leakage → it’s encrypted
    privileges → it’s encrypted
    replay →
    other? →
    Mitigating the risks:
    @vixentael
    

    View Slide

76. leakage → it’s encrypted
    privileges → it’s encrypted
    replay → ZKP (it’s encrypted ;)
    other? →
    Mitigating the risks:
    @vixentael
    

    View Slide

77. leakage → it’s encrypted
    privileges → it’s encrypted
    replay → ZKP (it’s encrypted ;)
    other? → tiny attack surface
    Mitigating the risks:
    @vixentael
    

    View Slide

78. ZKA elsewhere
    

    View Slide

79. shared
    audit logs
    complex docs,
    spreadsheets
    config files
    file system
    document store
    protection
    @vixentael
    

    View Slide

80. Is it difficult
    to implement?
    

    View Slide

81. Signal https://github.com/WhisperSystems/
    SignalProtocolKit/blob/master/AxolotlKit/Classes/
    Sessions/SessionBuilder.m
    @vixentael
    

    View Slide

82. Swift Alps Demo https://github.com/cossacklabs/theswiftalpsdemo/
    blob/master/ios-project/SwiftAlpsSecDemo/
    SwiftAlpsSecDemo/SessionDemo.swift
    github.com/
    cossacklabs/themis
    @vixentael
    

    View Slide

83. Hermes
    github.com/cossacklabs/
    hermes-core
    ODING IN PROGRESS
    CODING IN PROG @vixentael
    

    View Slide

84. Other examples
    https://tahoe-lafs.org/trac/tahoe-lafs
    The Least-Authority File Store
    https://tresorit.com/zerokit
    ZeroKit from Tresorit
    @vixentael
    

    View Slide

85. Recap
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

89. My other security slides
    https://github.com/
    vixentael/my-talks
    

    View Slide

90. @vixentael Mobile
    Tech Lead
    Feel free to reach me with any
    mobile security questions.
    I do check my inbox :)
    

    View Slide

91. Image credits
    www.flaticon.com
    freepik, linector, switficons, pixelperfect, smashicons
    Authors:
    

    View Slide