Making BIP-39 Seeds More Compact

Had this idea to make BIP-39 seeds super compact for QR or RFID. Just think about it... convert the wordlist into line numbers and base58 encode those. Each word would just be two characters. Maybe we can add a + at the end to show if there's an unknown word. Sounds neat, right?

A BIP-39 phrase is a binary value encoded as a series of words. If you're gonna 'compress' it, better to just use that binary value. You can't really squeeze it down any more.

This isn't real compression. The BIP39 words are already an encoded version of entropy plus a checksum. Swapping them for line numbers and base58 encoding just gives a custom format. Sure, it's smaller for QR codes but don't count on RFID/NFC.

I see your point, but we're trying to make it usable for humans, not just binary stuff. The seed in a text form is not practical. Even base58 feels excessive. Something like base46 would be better.

You're talking about the entropy, not the binary seed derived from it. Those words represent a pretty short binary value. You can check the entropy details in the BIP39 tool by toggling the right option.

You don’t need to compress that much. With a 2048-word dictionary, each word is 12 bits. For 12 words, that's just 144 bits, which is tiny. But this assumes the wordlist stays the same; it won't work with Electrum seeds.

Base64 isn’t user-friendly. Satoshi went with base58 for a reason. You won't gain anything with base64, plus it could confuse people. No matter the base, you'll still need two characters. Base58 is well known and keeps things consistent.

Using other bases for QR codes is fine. But users aren’t reading these strings anyway. That’s exactly why mnemonic words exist.

You brought up a good point, but neither base64 nor base58 is really 'human-usable'.

This discussion is going off track. What’s the real goal here? We want better methods to store Bitcoin seeds. The seed is the weakest security link; people often misunderstand its importance.

Seriously doubt it! If your camera can't read the code, making it smaller won't fix that. Sounds like a solution in search of a problem. Custom formats risk users forgetting how to recover their coins.

That’s an interesting thought. My old iPhone has a shaky camera, and it's tough to scan codes, yet smaller ones sometimes work better. Measuring how well QR codes are recognized would help find the best storage methods for seeds.

You really shouldn't scan private data on mobile devices. They're harder to keep secure than a PC. QR codes seem risky for private info.

This is a different discussion entirely. Metal plates for seed storage are much harder to wipe. I've even thought about using TOTP keys as backup codes for added security, but haven’t tested that yet.

If you can’t recover your seed in a secure spot, your backup is flawed. Metal plates don’t connect to the internet, but I could wipe one in seconds with a grinder. Phones? Much pricier to destroy.

Misunderstood your point about air gapped. I thought you meant air gapped TX signers. You don’t need a mobile for QR code reading. A simple webcam or a 2D barcode scanner will do the job just fine.

Yeah, you can get a webcam for cheap and with QtQR, it works. Those barcode scanners at stores are fast keyboards; they just type out what they read.

This is a good way to look at it. But let's keep it practical, yeah?