How is this different from public-key encryption?

Public-key uses asymmetric keys: anyone can encrypt with your public key, only you decrypt with your private key. Symmetric uses one shared secret: both sides have the same passphrase, both can encrypt and decrypt.

Will the recipient need PGP Tool?

No. The output is a standard OpenPGP message decryptable by any OpenPGP client — GnuPG, Kleopatra, ProtonMail, etc.

How do I share the passphrase securely?

Out of band: in person, over an end-to-end encrypted channel like Signal, or split across two channels. Never send the passphrase in the same message channel as the ciphertext.

Is symmetric encryption weaker than public-key?

Not inherently — AES-256 is as strong as the best public-key crypto. The weakness is operational: passphrases are typed by humans, often guessable, and anyone with the passphrase can read everything ever encrypted with it.

What if the passphrase is weak?

A weak passphrase is the whole game. Use the Password Generator to produce a strong one (24+ random characters or a 6-word EFF passphrase) and share it carefully.

Chiffrement symétrique

Chiffrez et déchiffrez des messages avec une passphrase partagée — sans clés.

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