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Aster Mail is a free, open-source Android email application focused on private communication through end-to-end encryption. It encrypts email messages, subject lines, and attachments locally before transmitting them. Communication between Aster users combines OpenPGP encryption with post-quantum cryptographic protection using ML-KEM-768. The service uses an X3DH and Double Ratchet protocol to strengthen message confidentiality. Users retain ownership of their encryption keys and can export them for use with compatible OpenPGP applications. Public keys are automatically distributed through Web Key Directory and key servers, simplifying encrypted communication. Its zero-access architecture prevents the service from reading protected messages. Account registration does not require a phone number or recovery email.
Features
- End-to-end email encryption protecting message contents, subjects, and attachments
- OpenPGP cryptography with Ed25519 and Curve25519 key support
- Post-quantum message protection using ML-KEM-768 and Double Ratchet protocols
- Portable encryption keys compatible with GPG and other OpenPGP clients
- Automatic public key discovery through Web Key Directory and key servers
- Privacy-focused account registration without mandatory phone numbers or recovery emails
Project Samples
