OfflineSeeds

• Accept every nonblank entry, including same-suit pairs.
• Never reverse a pair to avoid a blank.
• Never redraw only one card.
• Accept repeated cards, pairs, and words. Do not replace a result because it looks unusual.
• Keep accepted and rejected draws private.

Each word has one accepted card pair. A blank pair is a retry. This keeps all accepted words equally likely when the deck is well shuffled before each word.

Do not enter the words into this site, a phone, or any general-purpose computer. The first electronic entry of the 23 words is on the offline wallet itself.

Enter the complete phrase on a second compatible, air-gapped wallet. Compare the master key fingerprint on both devices. Wipe the verification device when you finish. Each extra device that sees the phrase adds exposure, so do this check only if you need it.

Two ordered cards give 52 × 51 = 2,652 possible pairs. The table accepts 2,048 pairs: 2,028 with different suits and 20 with the same suit. The other 604 pairs are blank. Each accepted pair maps to exactly one BIP39 word.

A draw is accepted with probability 2,048 / 2,652 ≈ 77.2%. Each accepted word is uniform over 2,048 possibilities and supplies log₂(2,048) = 11 bits. The 23 words supply 253 bits. The final Ace-to-8 card draw adds 3 random bits for a total of 256 bits. The 8-bit checksum adds no randomness.

If you always choose the same final position, the phrase has 253 bits rather than 256 bits. The final card draw is required for the 256-bit claim.

23 accepted words take approximately 29.8 attempts with approximately 6.8 blanks. A run with no blank at all has only a 0.26% probability.

If the most likely word is β times more likely than uniform, and the final draw supplies 3 independent bits, the min-entropy is 253 − 23 × log₂(β) + 3 bits. In the ideal riffle model, the distance from uniform is 0.334 after 7 shuffles and 0.167 after 8. This method only needs the top two cards, which mix faster than the full deck. Real hand shuffles can differ from that model, and no fixed count proves uniformity. The physical shuffle is the principal uncertainty.