End-to-end encryption and multi-device synchronisation for 6M users | Cossack Labs

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Case Bear B2C mobile app SUMMER 2019

End-to-end encryption and multi-device synchronisation for 6M users


  • productivity apps

  • note-taking apps

Technology stack

  • iOS

  • macOS

  • Apple cloud backend


  • GDPR

  • Encryption Export Regulations

Technology requirements

End-to-end encryption

Multi-device synchronisation

Easy to maintain cryptography


Transparency for users

Losing data is out of question

Security that doesn't ruin UI/UX

Mobile platform specifics


Products and services involved

Themis, <span class="font-normal">a cross-platform crypto library</span>

Themis, a cross-platform crypto library

We used cryptographic library Themis as a building block for transport layer encryption on application level, relying on its interoperability among required platforms and OSs.

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Cryptography engineering

Cryptography engineering

We've designed the end-to-end encryption protocol, assisted with implementation and verification.

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Mobile app security

Mobile app security

We've recommended platform-specific security controls for data protection outside of end-to-end encryption scope.

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Results and outcomes

Results and outcomes

Usable security is not a myth

It's possible to build secure and usable systems, but it takes efforts. Use our products 'as is' or build specialised solutions to take your data security to the next level.

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