[HACKTOBERFEST] End-to-End Encryption for File Transfers

[Ashish-Kumar-Dash]

Implement client-side (Flutter) file encryption before upload and decryption after download using libraries like AES or ChaCha20. Ensure keys are securely established or exchanged, possibly using Diffie-Hellman or similar. Update both backend and frontend workflows, and clearly document the encryption flow for users and contributors. Test files for corruption and provide error recovery steps

[aviralgarg05]

I would like to implement this for hacktoberfest