Some of you might remember my post from about a month ago where I shared a children's book I made that contains all 2,048 BIP39 words — the idea being that you can use the Book Cipher method to encode your seed phrase as page-line-word references and store those numbers separately from the book. The post blew up way more than I expected (400+ upvotes), and I got a ton of valuable feedback.

The most upvoted criticism: "This is just security through obscurity." Almost 400 upvotes on that comment alone. Other common concerns: "Now everyone knows the book", "A children's book is weird if you don't have kids", and "Amazon knows who bought it."

I took all of that seriously. Here's what I did about it.

What changed

1. A second book — for adults this time.

Several people pointed out that a children's book is a hard sell if you don't have kids sitting on your shelf. Fair point. So I created "777 Wisdoms for Every Day" — a collection of 777 numbered wisdoms that also contains all 2,048 BIP39 words. It looks like any other inspirational book. On your nightstand, in your luggage, on your office shelf — nobody thinks twice about a wisdom book.

2. A new encoding option that didn't exist before.

Because every wisdom in the book is numbered (#1 through #777), you now have an alternative to classic page-line-word encoding. You can use wisdom-number + word-position instead. Or mix and match. Or invent your own scheme. The point is: even if someone knows the concept AND knows the book, they still don't know how you encoded your references. That directly addresses the "security through obscurity" criticism — there are now too many variables for a simple lookup.

3. The "everyone knows the book" problem got smaller, not bigger.

Counter-intuitively, having multiple books actually helps. There are now two completely different books designed for this (a children's story and a wisdom book), with multiple encoding methods each. An attacker would need to know: which book you used, which encoding scheme, and have physical access to your number sequence. That's a lot of unknowns.

What hasn't changed

• It's still an additional layer, not a replacement. Your metal plate / paper backup stays in place. The book cipher is a complementary copy with built-in obfuscation.
• Two-factor by design. Book alone = useless. Numbers alone = useless. You need both, stored in different locations.
• The travel use case. A wisdom book in your luggage raises zero suspicion at borders. The codes look like phone numbers or whatever you disguise them as. Try that with a Cryptosteel in your carry-on.
• Metal plate combo. Instead of engraving 24 seed words on metal (screams crypto), engrave the book cipher codes: 47-3-5, 112-7-2, 83-1-11, ... — same durability, but now it's meaningless numbers.

Honest take

Some of the criticism from last time was absolutely valid. Security through obscurity IS a weakness — when it's your only layer. But as one layer among several (different storage locations, passphrase, metal backup, flexible encoding), I think book cipher adds real value. The second book doesn't fix every concern, but it addresses the biggest ones: more book options, more encoding flexibility, and a version that doesn't look out of place for adults without kids.

Happy to answer any questions — and genuinely curious if anyone from the last post actually ended up trying the book cipher approach.