When should I use passphrase encryption instead of a public key?

When there is no keypair in play: sealing a file for yourself, or sharing a secret with someone over a channel where you can both agree on a passphrase out of band. For ongoing correspondence with a known contact, public-key encryption scales better and does not require sharing a secret.

Is passphrase encryption less secure?

The cipher is the same strong symmetric encryption. The weak point is the passphrase and how you share it: a guessable passphrase or one sent over an insecure channel undermines everything. Use a long, random passphrase and share it through a separate trusted channel.

Can the recipient decrypt it with GnuPG?

Yes. Symmetric OpenPGP output is standard — anyone with the passphrase and any OpenPGP tool (GnuPG included) can decrypt it. No key import needed.

// glossary / symmetric-passphrase-encryption

Symmetric (passphrase) encryption.

Sealing data with a passphrase instead of a recipient's public key — the gpg -c style. The same passphrase locks and unlocks. No keypair required.

// definition

Symmetric encryption in OpenPGP derives a key from a passphrase you choose (via a memory-hard function) and encrypts the data under it. There is no public or private key involved — anyone who knows the passphrase can decrypt, and only they can.

What it is.

Most PGP usage is asymmetric: you encrypt to someone's public key, and only their private key opens it. Symmetric encryption skips the keypair entirely. You pick a passphrase; OpenPGP stretches it into a symmetric key and encrypts the data. To decrypt, you supply the same passphrase. This is what gpg --symmetric (gpg -c) does.

gpg --symmetric --armor secret.txt
# prompts for a passphrase, produces secret.txt.asc

Why it matters.

Sometimes there is no key to encrypt to. You want to seal a file for your future self, or hand a secret to someone you can phone but whose PGP key you don't have. Asking them to generate and exchange a keypair is overkill; agreeing on a strong passphrase out of band is enough.

The whole security of the result rests on the passphrase and how you share it. A short or reused passphrase, or one sent over the same channel as the ciphertext, defeats the purpose. Use a long random passphrase and a separate trusted channel to share it.

// in PGPony On the Encrypt tab, choose passphrase (symmetric) instead of selecting recipients, enter a passphrase, and PGPony produces standard OpenPGP symmetric output that any OpenPGP tool can open with the same passphrase. No keypair needed on either side.

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