Cross-Platform End-to-End Encrypted Messaging App

I'm looking to develop a messaging application that works on both iOS and Android. This app should support text messaging, voice messaging, and file sharing. The key feature of this app will be its security; I need it to provide end-to-end encryption to ensure privacy and security for users.

Ideal skills for this project would include:
- Cross-platform mobile app development
- Experience with implementing end-to-end encryption
- Timer deletion of messages
- Knowledge of secure messaging app development
- Proficiency in iOS and Android development

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Please provide examples of similar projects you've worked on in your bid.