Nym Key — Keys and passphrases for a pseudonymous online | nymkey.com
A BIP-39 seed is 12 or 24 common words that can rebuild every key your nym owns — if you store it where fire, water, and curiosity cannot reach.
The math first. The list holds 2,048 words at exactly 11 bits each: 12 words encode 128 bits of entropy with a 4-bit checksum, and 24 words encode 256 bits with an 8-bit checksum. The checksum bits live inside the final word, so the word list is self-verifying.
That checksum is your first line of defense against your own handwriting. A miswritten word fails validation in about 15 of 16 cases on a 12-word seed, and in about 255 of 256 cases on a 24-word seed — the software says 'invalid checksum' instead of silently deriving the wrong keys.
Generation happens offline. Boot a clean environment, create the seed, and never let it touch a synced device: the most common loss is not theft but a notes app quietly copying the words to the cloud before they are ever written down.
On narrow screens, swipe or scroll the plate sideways.
Storage is physical and redundant: the words written by hand, numbered, on paper or steel, in two separate locations. No photographs, no screenshots, no cloud drives — anything that syncs is a place the whole nym can be copied from without a trace.
The backup is finished only after a test restore. On a spare device, enter the words, confirm the derived keys or addresses match, and only then trust the copies. Repeat the drill once a year — twenty minutes annually is the entire maintenance budget of a recoverable nym.
The seed guards everything else in this guide: the passphrase sized with the entropy table and the second factor chosen from the comparison page both ultimately recover to these 12 or 24 words.
Further reading