Hi,
I'm very experienced with cryptography and cyber-security due my previous projects and studies.
If hired, I can deliver an implementation of a secure messaging web app (Encryption, decryption, cipher, digital signature: secure messages and guarantee integrity of messages).
If you're not satisfied I offer as many revisions as needed.
I'm available most hours of the day, you can contact me whenever you want.
You can check my profile and portfolio for previous reviews and samples.
Regards.