Passphrase.

The second factor for notes: the link travels one road, the phrase travels another, and reading requires both.

// definition

A passphrase is an optional secret required in addition to the link. It's normalized, stretched with PBKDF2-HMAC-SHA256 at 600,000 iterations, and mixed into the key derivation — the link alone no longer decrypts anything.

What it is

The link is the key, which makes the channel you send it through part of your security. A passphrase splits that risk in two: email the link, speak the phrase; text the link, hand over the phrase in person. An eavesdropper on either channel alone holds half a secret.

Why it matters

It also survives the worst case gracefully — a link pasted into the wrong chat, forwarded, or logged is unreadable noise to everyone who lacks the phrase, for as long as the note lives.

// in BurnPony The viewer prompts for the phrase and tells the recipient plainly: guessing happens only on their device and does not use up views. The right phrase opens the note; the ciphertext meanwhile was fetched exactly once.

Related terms

Common questions.

What makes a good note passphrase?

Length beats cleverness — a few random words outperform a punctuated password. And deliver it over a genuinely different channel than the link; a passphrase in the same email adds nothing.

Can I recover a note if the recipient loses the phrase?

No one can — not you, not the developer. Send them the phrase again if you still have it; otherwise burn the note and create a fresh one.

Get BurnPony

Free self-destructing encrypted notes for iPhone. Recipients need only a browser. No accounts, no tracking.